CN110503287A - Rice phenological period polynary meteorological data similarity method is measured with the dynamic time warping for mixing gradient based on form - Google Patents

Rice phenological period polynary meteorological data similarity method is measured with the dynamic time warping for mixing gradient based on form Download PDF

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CN110503287A
CN110503287A CN201810498045.4A CN201810498045A CN110503287A CN 110503287 A CN110503287 A CN 110503287A CN 201810498045 A CN201810498045 A CN 201810498045A CN 110503287 A CN110503287 A CN 110503287A
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姜海燕
杨乐
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Nanjing Agricultural University
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Nanjing Agricultural University
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Abstract

The present invention provides a kind of method that multivariable rice Meteorological series carry out similarity analysis in the crucial phenological period, belongs to agricultural weather the field of data mining.For linear drift problem caused by the temperature minimax exceptional value in Meteorological series, sequence Wave crest and wave trough erroneous matching problem and phenological period cause different in size caused by mutation rainfall etc., introduce dynamic time warping algorithm, the design for increasing form and mixing gradient, to improve the accuracy and simplicity of measurement, while meteorological data variation tendency and exceptional value are highlighted on crop influence.Specific steps are as follows: according to rice phenological period data cutting Meteorological series;Meteorological series first derivative second dervative calculates;It is given a mark at a distance from the original series and gradient sequence at different levels of dynamic form penalty based on form constant factor;Weighted blend original series are at a distance from gradients at different levels;It weights each meteorological variables sequence distance and forms distance between polynary Meteorological series;It is ranked up according to distance metric marking.

Description

Rice phenological period polynary gas is measured with the dynamic time warping for mixing gradient based on form Image data similarity method
One, technical field
The invention belongs to agricultural weather data analysis fields, are agricultural weather domain knowledge and multivariate time series similitude The crossing domain that the matching analysis algorithm be combined with each other.It is related to a kind of when can be used for non-linear, continuous, multivariable agricultural weather Ordinal number can be used for meteorology of the rice within the time of infertility under different phenological according to similarity analysis is carried out within the crucial phenological period Data similarity analysis.
Two, background technique
Meteorological index, such as the life of maximum temperature, minimum temperature, rainfall, sunshine time, radiant illumination to agricultural crops It is long influence it is big, and include these indexs history meteorological data data can usually react somewhere for a period of time in weather With the weather circumstance condition of crops, similarity measurement analysis is carried out according to the meteorological data data of historical years, it not only can be with It realizes the supplement to meteorological observation missing data, while also can provide foundation for the automatic division of climatic province.Therefore, towards The similarity analysis of agricultural weather data also becomes means commonly used by current agricultural weather data analysis.
The analysis of agricultural weather data similarity mainly by comparing maximum temperature in different regions or different time sections, The difference of the distribution characteristics of the meteorological datas sample such as minimum temperature, rainfall, sunshine time and variation tendency reaches close The purpose of degree sequence.Early stage meteorological data similarity analysis method is usual are as follows: utilizes mean temperature, standard deviation and anomaly etc. Meteorology statistical indicator describes meteorological data variation characteristic, and the degree of approximation for comparing statistical indicator realizes similarity measurement, this kind of Although method can effectively explain the feature of meteorological condition by statistical indicator on meteorology, when often considering one section In meteorological data distribution characteristics and variation tendency itself that have ignored data, weaken the extremum of meteorological element to Rice bring influences.Meteorological data temporal aspect is obvious simultaneously, has scholar to pass through the similarity distance degree of time series at present Figureofmerit is to calculate the similarity degree of the meteorological condition of between year border or different regions or mutually from degree.
The core of the similarity analysis of agricultural weather time series data is the selection of distance metric method, often to maximum temperature, The variables such as minimum temperature, illumination, rainfall carry out Euclidean distance calculating, then in the flat of each enterprising row distance of variable dimension Sum.Local climate similitude divides mainly meteorological to objective area and surrounding area historical years using Euclidean distance Data carry out similarity measurement, count the similar frequency, carry out region zones using similarity degree.Although this method is effectively simple, But the meteorological variation characteristic of Various Seasonal is not accounted for.The highest temperature between year border is analyzed using Euclidean distance combination KNN The variables meteorological data similarity degree such as degree, minimum temperature, rainfall and sunshine time utilizes the similar time meteorology number of history According to unknown meteorological data in replacement target breeding time.But aiming at the problem that similarity measurement of agricultural weather data, this method Often have ignored meteorological data exceptional value bring sequence data fluctuation abnormal problem, such as thermal extremes, extreme low temperature and drop Accumulation mutation of rainfall etc., so that occurring the case where " wave crest-trough " is misfitted in similitude matching process.
Since there are series modalities caused by thermal extremes, extreme low temperature, rainfall mutation for agricultural weather data The curve of cyclical fluctuations is abnormal, such as Wave crest and wave trough dislocation, thus common Euclidean distance not can solve the data with similar phenomenon away from From measurement.The metric algorithm of dynamic time warping is introduced thus, and dynamic time warping algorithm is a kind of by unevenly distorting Or bending solves similar sample sequence data originally and cannot do Similarity matching due to the linear drift that generates in time scale The method of problem, but dynamic time warping is typically only capable to solve the measurement of single meteorological index, analyzes as discussed above, In In real world, meteorological data belongs to multiple parameter data, there is the obvious mutation value in part in different variable dimensions.So, The dynamic time warping method for measuring similarity for studying multidimensional, which becomes, to be solved in the research of agricultural weather integrated condition similarity analysis One necessary work.The key of its similarity measurements flow function design is just to consider polynary meteorological temporal sequence simultaneously It is listed in the correct matching for the form that the potential change information abundant of each variable dimension excavates and each dimension is fluctuated in the presence of complexity.
Based on meteorological data, there are the applications of different variation characteristics on each phenological period difference variable latitude of rice herein Scene propose in conjunction with the rice phenological period segmentation with based on form and the multivariate time series for mixing gradient dynamic time warping Method for measuring similarity.So that polynary meteorological data similarity analysis is closer to actual scene within the phenological period.
Three, summary of the invention
It is more the invention proposes a kind of rice based on form and the dynamic time warping for mixing gradient crucial phenological period First meteorology time series data similarity measurements analysis method.Since there are bright for weather environment within the different phenological periods for rice Aobvious variation and distributional difference, in order to guarantee the real world close to farming growth of following of similarity measurement, institute It has carried out being divided according to the data of the whole story time in phenological period before carrying out meteorological data measurement in this way.And consider To agricultural weather data in time scale, the sequence similarity of the accumulated value generation of the extreme value and rainfall of temperature Distance inaccuracy caused by " wave crest-trough " abnormal matching problem of appearance is mixed, is proposed in dynamic time warping algorithm base On plinth, in conjunction with Meteorological series form factor and be capable of depth excavate meteorological data internal information mixing gradient, establish The method of new polynary agricultural weather data similarity measurement ensure that the meteorological data measurement in different phenological is more quasi- Really.
Polynary gas of the present invention based on form with the rice for the dynamic time warping for mixing gradient crucial phenological period As time series data similarity measurements analysis method, comprising the following steps:
Step 1: basic data prepares
The basic data that meteorological data similarity analysis need to prepare includes meteorological data (minimum temperature, maximum temperature, sunshine When number or rainfall), different cultivars the phenologys period such as emergence, jointing, heading, maturation history corresponding date of seeding.
Day by day Temperature Series set in n growth period duration of rice:
T=< T1, T2…Tn> andWherein TiIndicate meteorological day by day in the growth period duration of rice in n time Data,The high temperature of table, the lowest temperature, rainfall, sunshine time respectively.In order to emphasize agricultural weather data in time scale On the front and back date between data interdependency, be expressed as follows using multivariate time series:
It is time span, 1≤i that wherein K, which is variables number, the N such as maximum temperature, minimum temperature, rainfall, sunshine time, ≤ K, 1≤j≤N, N indicate time span, the most variable numbers of the variable possessed that K is indicated, χijIndicate that i-th of variable exists The actual observation value at jth time point.
The somewhere n kind growth period duration of rice date data:
Yn=< ySowing time, ySeeding stage, yTillering stage, yJointing stage, yBoot stage, yHeading stage, yFlorescence, yPustulation period, yMaturity period>, wherein y indicates entry into phenology Phase start time, n indicate the time of institute's band, and gathering interior subscript indicates to define the phenological period of entrance.
Step 2: according to the division Meteorological series data in crop phenological period
Meteorological data feature itself and variation tendency feature within the different phenological periods is all different (such as Fig. 2), for Entire breeding time carry out all meteorological datas carry out similarity measurements analysis can because this complex scene and there are biggish mistakes Difference loses precision.So when for the meteorological data similarity analysis of specified kind crop, in order to enable measurement is more Accurately, the different phenological whole story time progress data segmentation in real world according to the kind crop is needed.
The date data record of kind growth period duration of rice is specified in the somewhere n: into the time in certain class phenological period, It is considered that when these two adjacent into the time in phenological period are that the kind entered needed for the latter phenological period for a period of time Between, i.e. Yn=< ySowing time, ySeeding stage, yTillering stage, yJointing stage, yBoot stage, yHeading stage, yFlorescence, yPustulation period, yMaturity period> in, it is believed that the affiliated phenological period It is as follows respectively: W<the seeding stage, n>=< ySowing time, ySeeding stage>, W<tillering stage, n>=< ySowing time, ySeeding stage>, WPhase<jointing stage, n>=< ySowing time, ySeeding stage>, W<boot stage, n>=< ySowing time, ySeeding stage>, W<heading stage, n>=< ySowing time, ySeeding stage>, W<florescence, n>=< ySowing time, ySeeding stage>, W<the pustulation period, n>=< ySowing time, ySeeding stage>, W<the maturity period, n>=< ySowing time, ySeeding stage>。
And according to the period in phenological period of above-mentioned expression, Temperature Series set day by day can be directed in n growth period duration of rice Tday=< T1, T2...TnThe meteorological data segmentation of > progress different phenological, the different growing of available somewhere kind Meteorological data set:
Sn=< SSowing time, SSeeding stage, STillering stage, SJointing stage, SBoot stage, SHeading stage, SFlorescence, SPustulation period, SMaturity period>, S indicates that the n-th time is corresponding Meteorological data in the subscript affiliated phase in phenological period.
Step 3: the similarity measurement between target sample
The step 3 includes:
Agricultural weather data inherently have extremely strong complexity, are difficult inside statement from the data information on surface merely Variation characteristic.In order to excavate the speed amplitude of variation tendency and variation of the agricultural weather data under different variables, introduce The representation method of the data of Primordial Qi image data and its gradient.
The meteorological data of gradient more than step 3.1 describes
For agricultural weather data, carry out first as the raw value in step 1 multivariate time series indicate.For Understanding of the enhancing to its variation tendency, introducing gradient in research indicates its variation tendency.First derivative is calculated first, it is public Formula is as follows:
What i therein, j were respectively indicated be same sample same meteorological element variable under one group of time scale sequence q Different corresponding points positions.
It repeats above-mentioned formula (1) and calculates the second dervative for obtaining the sequence, i.e., the speed and variation that it changes on sequence q Amplitude expression, until all the points are calculated and terminate in the sequence.Thus constitute vectorTo indicate sequence All information of q.
The design of step 3.2 form factor
Since the exceptional value in agrometeorological elements would generally bring very big influence to the growth of rice, so introducing shape The basic goal of the state factor is to guarantee that sequence can kiss when measuring marking on the maximum similarity degree of waveform It closes, highlights due to such as cumulant of rainfall and the high temperature low temperature exception bring sequence of temperature in agricultural weather variable Fluctuation, influence brought by can be more when carrying out similitude weather data analysis the considerations of exceptional value.
Weight is assigned according to phase difference for the design of form factor, and mainly, is guaranteed when Wave crest and wave trough matches Accurately, it and excludes because deliberately carrying out " wave crest-wave crest ", " trough-trough " is matched and had ignored between two correspondingly-shapeds Existing phase difference, the Wave crest and wave trough matching that phase difference generates too far have exceeded a certain range and just lose meaning.
The step 3.2 is as follows:
The design of step 3.2.1 form factor constant
When the use of step very crucial in dynamic time warping algorithm being exactly the path matrix for creating m*n, two corresponding points aiAnd bjDistance on matrix indicates.It is devised herein according to the phase difference between two o'clock and determines weighted value, in other words, when aiAnd bjWhen point is close, weight assigns smaller value.In entire sequence distance calculating process, optimum distance is defined as 0.Since needing Weight assignment is carried out according to the phase difference of two corresponding points, it is necessary to control coefrficient g be increased to the phase difference, also illustrated that Control the empirical of the variation curvature of weighting function.
The design of step 3.2.2 dynamic form penalty
As described above, the phase difference utilized determines whether two o'clock approaches, it is expressed as | ai-bj|, in order to describe due to phase difference Caused weight is in notable difference, introduces logic weighting function (MLWF), the wave crest according to caused by exceptional value in meteorological data Trough irregular the case where occurring, it is as follows to construct penalty:
In order to further decrease the time complexity in calculating process, calculating is converted by the phase difference of corresponding points in research Difference of the sequence of points of meteorological time series to be matched to known meteorological time series midpoint.Distance is indicated using c in text The position of formation center [m/2].Comprehensively consider that form dynamic form penalty as follows:
The hybrid weight design of the meteorological data of gradient more than step 3.3 description
It is indicated by all information that previous step obtains q and then is calculated using formula (2) respectively in meteorological temporal sequence Distance d under column original value, first derivative sequence and second dervative sequence0、d1And d2D is then carried out by weighting0、d1With d2It is cumulative, obtain final the distance between two samples, specific formula is as follows:
D (i, j)=w0*d0(i, j)+w1*d1(i, j)+w2*d2(i, j) (4)
In summary all steps, it can be deduced that overall measure representation formula is as follows:
In formula, it is thus necessary to determine that parameter have g, w0, w1, w2.Pass through experiment (such as Fig. 3), it is determined that this four parameters are optimal Combination: w0=1, w1=w2=2, g=0.2.
According to above-mentioned formula (5), calculating each meteorological variables of target year sequence are agreed to same in kind historical years with locality In phenological period meteorological data data sample sequence of points to the distance between, export distance.
Step 3.4 constructs distance matrix, calculates shortest path strength using Dynamic Programming, is averaging distance.
It is cumulative using formula (5) calculated same time point distance based on weight 1, utilize formula (6) the filling distance square Battle array is as follows:
It is as follows to obtain distance matrix:
Use dynamic programming algorithm, calculating matrix Dm*nMiddle shortest path, the method is as follows:
Step 3.4 successively calculates target time Meteorological series and all historical years Meteorological series within the same phenological period Distance terminates until all historical years calculate, and exports all distance marking.
Step 4: being ranked up according to similarity measurement distance
Agricultural weather data under the specified crop varieties phenological period for calculating the target time according to the measure in step 3 The sample and other history years are obtained with the agricultural weather data under the same middle kind crop same phenological period of other historical years The distance marking table of the corresponding sample of part.Then output is ranked up according to the score of marking table height from high to low, if distance is beaten Split-phase is the same as work output side by side.First of output sequence indicate in specified sample with target time agricultural weather data In the least similar time, the last one indicates the time most like with target time data agricultural weather data under particular cases.
It is as follows to improve major embodiment compared with existing agricultural weather data similarity measure by the present invention:
(1) redescribing for agricultural weather data is carried out using multivariate time series, ensure that in subsequent similitude point During analysis, data are described closer to real physical world;
(2) the phenological period whole story according to specified kind has been carried out in the data handling procedure for carry out similarity analysis Time segmentation, not only reduces the complexity of operation, at the same also contemplate crop under the different phenological to meteorological element according to Rely degree;
(3) form factor (form constant factor and dynamic form punishment system are increased in carrying out similitude matching process Number), it ensure that " wave crest-wave crest " of Meteorological series data, " trough-trough " are effectively matched;
(4) increase the mixing gradient that can be excavated in meteorological data in variation tendency information, it is abundant be utilized it is existing Meteorological series data information so that similarity measurement is more accurate.
Four, Figure of description
Fig. 1 measures rice phenological period polynary meteorological data similarity method with the dynamic time warping for mixing gradient based on form Flow chart
Fig. 2 2001 and Yixing force in 2005 educate round-grained rice rice anthesis Meteorological series variation tendency (minimum temperature (a), highest Temperature (b), sunshine time (c) and rainfall (d))
The Yixing City Fig. 3 force educates round-grained rice rice classification accuracy result figure under the combination of each coefficient under different cluster numbers labels
Five, specific embodiment
The present invention is further described below by way of case study on implementation
Embodiment
By taking the force of Yixing City plantation educates round-grained rice rice varieties as an example, the local history meteorological data over the years in Yixing is educated for force Round-grained rice rice varieties heading stage meteorological data carries out similar time analysis.In conjunction with attached drawing 1, present embodiment is illustrated:
Step 1: driving data prepares
The meteorological data historical data that selection is provided by national weather data sharing center, including max. daily temperature (DEG C), Daily minimum temperature (DEG C), rainfall (mm), sunshine time (h) and corresponding area specify date in the phenological period over the years note of kind Data are recorded, data description used is tested and is shown in Table 1, table 2.
Table 1 tests meteorological data and table is described in detail
Table 2 tests force and educates round-grained rice heading stage record date tables of data
Step 2: being divided according to the meteorological data in crop phenological period
Experiment divides the heading stage record data that the Yixing City force used educates the correspondence time of round-grained rice rice, as shown in table 2 Data corresponding meteorological data is split, obtain segmentation result, table 3 is the segmentation result example of heading stage in 1994.
Table 3 tests meteorological data and table is described in detail
Step 3: the similarity measurement between target sample
The step 3 includes:
Agricultural weather data inherently have extremely strong complexity, are difficult inside statement from the data information on surface merely Variation characteristic.In order to excavate the speed amplitude of variation tendency and variation of the agricultural weather data under different variables, introduce The representation method of the data of Primordial Qi image data and its gradient.
The meteorological data of gradient more than step 3.1 describes
For agricultural weather data, carry out first as the raw value in step 1 multivariate time series indicate.For Understanding of the enhancing to its variation tendency, introducing gradient in research indicates its variation tendency.First derivative is calculated first, it is public Formula is as follows:
What i therein, j were respectively indicated be same sample same meteorological element variable under one group of time scale sequence q Different corresponding points positions.
It repeats above-mentioned formula (1) and calculates the second dervative for obtaining the sequence, i.e., the speed and variation that it changes on sequence q Amplitude expression, until all the points are calculated and terminate in the sequence.Thus constitute vectorTo indicate sequence All information of q.
The design of step 3.2 form factor
Since the exceptional value in agrometeorological elements would generally bring very big influence to the growth of rice, so introducing shape The basic goal of the state factor is to guarantee that sequence can kiss when measuring marking on the maximum similarity degree of waveform It closes, highlights due to such as cumulant of rainfall and the high temperature low temperature exception bring sequence of temperature in agricultural weather variable Fluctuation, influence brought by can be more when carrying out similitude weather data analysis the considerations of exceptional value.
Weight is assigned according to phase difference for the design of form factor, and mainly, is guaranteed when Wave crest and wave trough matches Accurately, it and excludes because deliberately carrying out " wave crest-wave crest ", " trough-trough " is matched and had ignored between two correspondingly-shapeds Existing phase difference, the Wave crest and wave trough matching that phase difference generates too far have exceeded a certain range and just lose meaning.
The step 3.2 is as follows:
The design of step 3.2.1 form factor constant
When the use of step very crucial in dynamic time warping algorithm being exactly the path matrix for creating m*n, two corresponding points aiAnd bjDistance on matrix indicates.It is devised herein according to the phase difference between two o'clock and determines weighted value, in other words, when aiAnd bjWhen point is close, weight assigns smaller value.In entire sequence distance calculating process, optimum distance is defined as 0.Since needing Weight assignment is carried out according to the phase difference of two corresponding points, it is necessary to control coefrficient g be increased to the phase difference, also illustrated that Control the empirical of the variation curvature of weighting function.
The design of step 3.2.2 dynamic form penalty
As described above, the phase difference utilized determines whether two o'clock approaches, it is expressed as | ai-bj|, in order to describe due to phase difference Caused weight is in notable difference, introduces logic weighting function (MLWF), the wave crest according to caused by exceptional value in meteorological data Trough irregular the case where occurring, it is as follows to construct penalty:
In order to further decrease the time complexity in calculating process, calculating is converted by the phase difference of corresponding points in research Difference of the sequence of points of meteorological time series to be matched to known meteorological time series midpoint.Distance is indicated using c in text The position of formation center [m/2].Comprehensively consider that form dynamic form penalty as follows:
The hybrid weight design of the meteorological data of gradient more than step 3.3 description
It is indicated by all information that previous step obtains q and then is calculated using formula (2) respectively in meteorological temporal sequence Distance d under column original value, first derivative sequence and second dervative sequence0、d1And d2D is then carried out by weighting0、d1With d2It is cumulative, obtain final the distance between two samples, specific formula is as follows:
D (i, j)=w0*d0(i, j)+w1*d1(i, j)+w2*d2(i, j) (4)
In summary all steps, it can be deduced that overall measure representation formula is as follows:
In formula, it is thus necessary to determine that parameter have g, w0, w1, w2.Pass through experiment (such as Fig. 3), it is determined that this four parameters are optimal Combination: w0=1, w1=w2=2, g=0.2.According to above-mentioned formula (5), each meteorological variables of target year sequence and locality are calculated Agree in kind historical years in the same phenological period meteorological data data sample sequence of points to the distance between, export distance.
Step 3.4 constructs distance matrix, calculates shortest path strength using Dynamic Programming, is averaging distance.
The calculated same time point distance of formula 5 is utilized based on weight 1 is cumulative, using formula (6) the filling distance matrix, It is as follows:
It is as follows to obtain distance matrix:
Use dynamic programming algorithm, calculating matrix Dm*nMiddle shortest path, the method is as follows:
Step 3.4 successively calculates target time Meteorological series and all historical years Meteorological series within the same phenological period Distance terminates until all historical years calculate, and exports all distance marking.
According to above-mentioned formula (7), calculates in target year and local agreement kind historical years and agree to meteorological number in the phenological period According to the distance between data sample, distance sequence is exported, what is calculated herein is that Yixing force educates round-grained rice rice 2011 and historical years The distance of (1994-2011 is removed 2006,2007,2008) between the meteorological data in this period at heading stage is beaten Point, export result such as table 4:
Table 4 2011 years and historical years the meteorological data similarity distance within heading stage are given a mark table
Step 4: being ranked up according to similarity measurement distance
Agricultural weather data under the specified crop varieties phenological period for calculating the target time according to the measure in step 3 The sample and other history years are obtained with the agricultural weather data under the same middle kind crop same phenological period of other historical years The distance marking table of the corresponding sample of part.Then output is ranked up according to the score of marking table height from high to low.Output sequence First indicate time least similar with target time agricultural weather data, the last one table in specified sample Show the time most like with target time data agricultural weather data under particular cases.By time in table 4 according to marking from It is high to Low to be ranked up, it obtains educating round-grained rice with Yixing force and gives a mark sequencing table in the similarity distance of 2011 heading stages and historical years, Such as table 5:
Table 5 2011 years and historical years the meteorological data similarity distance within heading stage are given a mark sequencing table
Time
2005
2004
2002
2010
1994
2003
2000
1996
1997
1999
2001
1998
2009
1995
In table 5, it can be seen that it is least similar at 2011 heading stages and 2005 in historical years that Yixing force educates round-grained rice, It is most like with nineteen ninety-five.

Claims (5)

1. measuring rice phenological period polynary meteorological data similarity method with the dynamic time warping for mixing gradient based on form
It mainly comprises the steps that
1) designated area meteorological data and this area specify the phenological period date data of kind to prepare
2) according to the division Meteorological series data in crop phenological period
3) based on form with mix the similitude between gradient DTW metric objective sample
4) it is ranked up according to similarity measurement distance marking.
2. according to claim 1 based on form and the crucial phenological period multivariable agricultural weather number of the crops for mixing gradient According to similarity measurements analysis method, it is characterised in that carry out agricultural weather data according to according to multivariate time series in step 1) It redescribes.In order to increase the interdependency in time scale, it is expressed as follows using multivariate time series:
Wherein K is the variables number such as maximum temperature, the lowest temperature base of a fruit, rainfall, sunshine time, and N is time span, 1≤i≤ K, 1≤j≤N, N indicate time span, the most variable numbers of the variable possessed that K is indicated, χijIndicate i-th of variable in jth The actual observation value at time point.
3. according to claim 1 based on form and the crucial phenological period multivariable agricultural weather number of the crops for mixing gradient According to similarity measurements analysis method, it is characterised in that divided in step 2) according to the meteorological data in crop phenological period.Crop is not It is all different to the degree of dependence of meteorological element in the same phenological period, all meteorological datas, which are carried out, for entire breeding time carries out phases Like property metric analysis, there is no actual meanings, and increase the complexity of calculating.So for specified kind crop When meteorological data similarity analysis, in order to enable measurement is more accurate, need according to the kind crop in real world not Data segmentation is carried out with the whole story time in phenological period.
What is recorded in the date data that kind growth period duration of rice is specified in the somewhere n is the time thought into certain phenological period, It is considered that these two adjacent into the time in phenological period are the time needed for the kind enters the latter phenological period for a period of time, That is Yn=< ySowing time, ySeeding stage, yTillering stage, yJointing stage, yBoot stage, yHeading stage, yFlorescence, yPustulation period, yMaturity period> in, it is believed that affiliated phenological period difference It is as follows: W<the seeding stage, n>=< ySowing time, ySeeding stage>, W<tillering stage, n>=< ySowing time, ySeeding stage>, WPhase<jointing stage, n>=< ySowing time, ySeeding stage>, W<boot stage, n>= <ySowing time, ySeeding stage>, W<heading stage, n>=< ySowing time, ySeeding stage>, W<florescence, n>=< ySowing time, ySeeding stage>, W<the pustulation period, n>=< ySowing time, ySeeding stage>, W<the maturity period, n>=< ySowing time, ySeeding stage>。
And according to the period in phenological period of above-mentioned expression, Temperature Series set T day by day can be directed in n growth period duration of riceday= <T1, T2...TnThe meteorological data segmentation of > progress different phenological, the gas of the different growing of available somewhere kind Image data set:
Sn=< SSowing time, SSeeding stage, STillering stage, SJointing stage, SBoot stage, SHeading stage, SFlorescence, SPustulation period, SMaturity period>, S indicates the n-th time corresponding subscript Meteorological data in the affiliated phase in phenological period.
4. according to claim 1 based on form and the crucial phenological period multivariable agricultural weather number of the crops for mixing gradient According to similarity measurements analysis method, it is characterised in that the similarity measurement in step 3) between target sample.It calculates under different year The key of similarity degree under the time serieses of meteorological datas such as the highest temperature is low, minimum temperature, rainfall, sunshine time is energy It is enough to carry out sequences match in the sample meteorological data of different year, it is only guaranteed to have arrived " wave crest-wave crest ", " trough-trough " Correct matching, the distance between obtained sample is just accurate.So needing to increase the shape to data sequence in calculating process The matched control of state and hope obtain in more Meteorological series data variation tendency information.
The meteorological data of gradient more than step 3.1 describes
For agricultural weather data, carry out first as the raw value in step 1 multivariate time series indicate.In order to increase By force to the understanding of its variation tendency, introducing gradient in research indicates its variation tendency.First derivative is calculated first, and formula is such as Under:
What i therein, j were respectively indicated is that sequence q is not under one group of time scale for the same meteorological element variable of same sample With corresponding points position.
It repeats above-mentioned formula (1) and calculates the second dervative for obtaining the sequence, i.e., the width of it changes on sequence q speed and variation The expression of degree, until all the points are calculated and terminate in the sequence.Thus constitute vectorTo indicate the institute of sequence q There is information.
The design of step 3.2 form factor
Since the exceptional value in agrometeorological elements would generally bring very big influence to the growth of crops, so introducing form The basic goal of the factor is in order to guarantee that sequence can coincide when measuring marking on the maximum similarity degree of waveform, by force The high temperature low temperature exception bring sequence fluctuation due to the cumulant and temperature of such as rainfall in agricultural weather variable, In are adjusted The brought influence of exceptional value of can be more when progress similitude weather data analysis the considerations of.
Weight is assigned according to phase difference for the design of form factor, and mainly, it is accurate when Wave crest and wave trough matches to guarantee, And it excludes because deliberately carrying out " wave crest-wave crest ", " trough-trough " is matched and had ignored existing between two correspondingly-shapeds Phase difference, the Wave crest and wave trough matching that phase difference generates too far have exceeded a certain range and just lose meaning.
The step 3.2 is as follows:
The design of step 3.2.1 form factor constant
When the use of step very crucial in dynamic time warping algorithm being exactly the path matrix for creating m*n, two corresponding points aiAnd bj Distance on matrix indicates.It is devised herein according to the phase difference between two o'clock and determines weighted value, in other words, work as aiAnd bj When point is close, weight assigns smaller value.In entire sequence distance calculating process, optimum distance is defined as 0.Since needing basis The phase difference of two corresponding points carries out weight assignment, it is necessary to increase control coefrficient g to the phase difference, also illustrate that control weight The empirical of the variation curvature of function.
The design of step 3.2.2 dynamic form penalty
As described above, the phase difference utilized determines whether two o'clock approaches, it is expressed as | ai-bj|, in order to describe to cause due to phase difference Weight be in notable difference, introduce logic weighting function (MLWF), the Wave crest and wave trough according to caused by exceptional value in meteorological data Irregular the case where occurring, it is as follows to construct penalty:
In order to further decrease the time complexity in calculating process, converts the phase difference of corresponding points in research and calculate to quilt Difference of the sequence of points of matched meteorological time series to known meteorological time series midpoint.Distance sequence is indicated using c in text The position at center [m/2].Comprehensively consider that form dynamic form penalty as follows:
The hybrid weight design of the meteorological data of gradient more than step 3.3 description
It is indicated by all information that previous step obtains q and then is calculated respectively using formula (2) in meteorological time series original Distance d under initial value, first derivative sequence and second dervative sequence0、d1And d2D is then carried out by weighting0、d1And d2's It is cumulative, final the distance between two samples are obtained, specific formula is as follows:
D (i, j)=w0*d0(i, j)+w1*d1(i, j)+w2*d2(i, j) (4)
In summary all steps, it can be deduced that overall measure representation formula is as follows:
In formula, it is thus necessary to determine that parameter have g, w0, w1, w2.Pass through experiment, it is determined that the optimal combination of this four parameters: w0= 1, w1=w2=2, g=0.2.
According to above-mentioned formula (5), same phenology in each meteorological variables of target year sequence and local agreement kind historical years is calculated In phase meteorological data data sample sequence of points to the distance between, export distance.
Step 3.4 constructs distance matrix, calculates shortest path strength using Dynamic Programming, is averaging distance.
It is cumulative using formula (5) calculated same time point distance based on weight 1, using formula (6) the filling distance matrix, such as Under:
It is as follows to obtain distance matrix:
Use dynamic programming algorithm, calculating matrix Dm*nMiddle shortest path, the method is as follows:
Step 3.4 successively calculate target time Meteorological series and all historical years Meteorological series within the same phenological period away from From until the calculating of all historical years terminates, and exporting all distance marking.
5. according to claim 1 based on form and the crucial phenological period multivariable agricultural weather number of the crops for mixing gradient According to similarity measurements analysis method, it is characterised in that step 4) is ranked up according to similarity measurement distance.According in step 3 Under the specified crop varieties phenological period that measure calculates the target time agricultural weather data and other historical years it is same in Agricultural weather data under the kind crop same phenological period obtain the sample and give a mark at a distance from the corresponding sample of other historical years Table.Then output is ranked up according to the score of marking table height from high to low, if apart from identical work output side by side of giving a mark.It is defeated First of sequence indicates the time least similar with target time agricultural weather data in specified sample out, last The time most like with target time data agricultural weather data under a expression particular cases.
CN201810498045.4A 2018-05-18 2018-05-18 Rice phenological period polynary meteorological data similarity method is measured with the dynamic time warping for mixing gradient based on form Pending CN110503287A (en)

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