JPH05314269A - Graph preparing device - Google Patents

Abstract

PURPOSE:To prepare a graph only by directly inputting respective points constituting the graph onto a picture while using a stylus pen or the like. CONSTITUTION:When the preparation of a polygonal graph is selected, for example, a CPU 1 displays a graph preparing picture through a display control part 9 on an LCD 8. When the unit or scale of X and Y axes in the graph preparing picture is designated through a tablet 6 by a stylus pen 4, the CPU 1 receives these set values through a tablet control part 7 and displays them on the LCD 8. Afterwards, when any arbitrary point in the X and Y axes displayed on the LCD 8 is instructed through the tablet 6 by the stylus pen 4, the CPU 1 inputs the instructed point through the tablet control part 7, stores it in a main memory 2 as coordinate data, displays the instructed point through the display control part 9 onto the LCD 8, afterwards, further displays a straight lines connecting the respective points on the LCD 8, and prepares the polygonal graph.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graph creating apparatus composed of a personal computer or the like, and more particularly to a data input system for expanding the graph.

[0002]

2. Description of the Related Art Conventionally, there is a method of drawing a graph as a method of visually expressing the magnitude of a numerical value and its change. When displaying the above graph on a personal computer etc., enter the numerical value for expanding the graph into a table creation tool such as a spreadsheet using a keyboard etc. to create table data in advance, and then use this table data. The graph is displayed on the display after being processed by the personal computer.

However, in the case of displaying a graph on a personal computer or the like by the above-mentioned method, if a table such as a spreadsheet is not prepared in advance as the data to be the basis for developing the graph, the numerical value However, there is a drawback that the operator cannot understand the erroneous input and the like unless he / she digitally inputs the numerical value and then displays it as a graph. In addition, in such a method, once it is displayed as a graph, it is not possible to add a new graph directly, and in such a case also, the numerical value for expanding the above-mentioned graph to be added must be input to the spreadsheet. However, there is a disadvantage that it takes time and labor.

[0004]

When numerical values are displayed as a graph on a personal computer or the like as described above, the numerical values are input to a table creation tool such as a spreadsheet using a keyboard or the like before displaying the graph. Therefore, there is a drawback that it is impossible to intuitively create a graph by directly inputting numerical values on the screen. Moreover, once it is displayed as a graph, it is not possible to add a new graph directly to this graph, and in such a case as well, enter a numerical value for expanding the graph to be added to the spreadsheet from a keyboard or the like. However, there is a drawback that it takes time and labor.

In view of the above, the present invention eliminates the above-mentioned drawbacks, and the positions of points forming the above numerical values or graphs can be directly displayed on the screen by a stylus pen or the like without creating numerical values for developing the graphs in advance as table data. It is an object of the present invention to provide a graph creation device capable of creating and displaying a graph by inputting using it.

[0006]

SUMMARY OF THE INVENTION The present invention is a graphic creation apparatus equipped with a display input device capable of inputting data from a screen displaying characters and graphics using a pen or the like, and creates a graph using the pen. Attribute data setting means for displaying a screen for inputting attribute data for the display on the display input device, and a graph is created based on the attribute data input by the pen from the screen displayed by the attribute data setting means. A graph data input means for displaying a graph creation area having a reference axis for displaying on the screen, and a numerical value corresponding to the position designated by the pen on the reference axis displayed on the screen by the graph data input means. And a numerical value input means for inputting the attribute in the graph creation area on the screen based on the numerical value input by the numerical value input means. Having the configuration and a graph creation unit for creating and displaying the type of graph specified by chromatography data.

As a configuration different from the above of the present invention, in a graphic creation device equipped with a display input device capable of inputting data from a screen for displaying characters and graphics using a pen or the like, a graph is created using the pen. Attribute data setting means for displaying a screen for inputting attribute data for creating on the display input device, and a graph based on the attribute data input by the pen from the screen displayed by the attribute data setting means. Graph data input means for displaying a graph creation area having a reference axis for creating on the screen, and a position specified by the pen in the graph creation area displayed on the screen by the graph data input means. Position input means for inputting corresponding coordinate data, and a graph on the screen based on the coordinate data input by the position input means. Having the configuration and a graph creation unit for creating and displaying graphs of the specified type in the attribute data in the creation area.

[0008]

In the graph creating apparatus of the present invention, the attribute data setting means displays on the display input device a screen for inputting attribute data for creating a graph using a pen.
The graph data input means displays a graph creation area having a reference axis for creating a graph on the screen displayed by the attribute data setting means on the basis of the attribute data input by the pen. The numerical value input means inputs the numerical value corresponding to the position designated by the pen on the reference axis displayed on the screen by the graph data input means. The graph creating means creates and displays the graph specified by the attribute data in the graph creating area on the screen based on the numerical value input by the numerical value inputting means.

In the graph creating apparatus of the present invention having an operation different from the above, the attribute data setting means displays a screen for inputting attribute data for creating a graph using the pen on the display input device. The graph data input means displays a graph creation area having a reference axis for creating a graph on the screen displayed by the attribute data setting means on the basis of the attribute data input by the pen. The position input means inputs the coordinate data corresponding to the position designated by the pen in the graph creation area displayed on the screen by the graph data input means. The graph creating means creates and displays the graph specified by the attribute data in the graph creating area on the screen based on the coordinate data input by the position inputting means.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a graph creating apparatus of the present invention. Reference numeral 1 is a CPU that controls the creation and display of a graph and the entire apparatus, and 2 is the CPU 1
A main memory in which programs for controlling the computer and various data are stored, 3 is an external storage device such as a floppy disk device, 4
Is a stylus pen that specifies the coordinates on the tablet 6, 5
Is a stylus control unit that controls the operation of the stylus pen 4, 6 is a tablet that inputs coordinate data of the position designated by the stylus pen 4, 7 is a tablet control unit that controls the operation of the tablet 6, and 8 is the input point An LCD for displaying the created graph and the like, a display controller 9 for controlling the display operation of the LCD 8, and a bitmap memory 10 for expanding the display data to be displayed on the LCD 8. The tablet 6 and the LCD 8 are integrally molded to form a display input device.

FIG. 2 is a diagram showing an example of the external appearance of the graph creating apparatus shown in FIG. Reference numeral 11 denotes a graph creating device, on the upper surface of which a display input surface for inputting information with the stylus pen 4 and displaying the input information or the processed information is provided. The external storage device 3 is attached to the side surface of the device 11.

FIG. 3 is a diagram showing the configuration of the display input surface 12. The transparent tablet 6 is overlaid and integrally molded on the upper surface of the LCD 8 shown in FIG. 1, and the upper surface of the tablet 6 serves as the display input surface 12 described above.

Next, the operation of this embodiment will be described. First, when the device is powered on, the CPU 1 displays an initial screen as shown in FIG. 4 (A) on the LCD 8 via the display controller 9 according to the program in the main memory 2. At this time, the display control unit 9 develops the graphic or character to be displayed on the LCD 8 in the bitmap memory 10 and then displays this.
To display. The operator selects the stylus pen 4 from the pop-up menu 41 on the initial screen displayed in FIG.
Use to select "1, Create graph". When the CPU 1 inputs the selection information via the tablet controller 7,
The “1, graph creation” is displayed in reverse on the LCD 8 via the display control unit 9. After that, the CPU 1 displays on the LCD 8 a screen for creating the graph as shown in FIG. This screen is a screen for selecting whether a graph to be created is a new graph or an existing file. When the operator selects, for example, “1, new” from the pop-up menu 41 with the stylus pen 4, For the same reason as above, “1, new” is highlighted. CPU1
LC, because the graph creation is "1, new"
A screen for selecting the type of graph as shown in FIG. 4C is displayed at D8. When the operator looks at this screen and selects "2, line graph" from the pop-up menu 41 using the stylus pen 4, the display of "2, line graph" is highlighted and the CPU 1 newly creates a line graph. The device is set in the mode for creating, and the above selection process is terminated.

When "2, line graph" is selected in the above selection process, the CPU 1 displays a menu bar 51 on the upper part of the display input surface 12 as shown in FIG. The reference X-axis and Y-axis 52 are displayed. Then, when the X-axis and Y-axis scales are selected with the stylus pen 4 in the menu bar 51 of FIG. 5A, the CPU 1 determines the X- and Y-axis scales as shown in FIG. 5B. The screen is displayed on the display input surface 12. On this screen, the “scale” of the menu bar 51 is highlighted, and the input area 53 is displayed in the center of the screen. Therefore, when the operator manually inputs desired information to each item in the input area 53 with the stylus pen 4, the input information is immediately displayed on the display input surface 12 by the CPU 1. At the same time, when the operator points the scale on the X-axis with the stylus pen 4, FIG.
The pointed X-axis is highlighted as shown in FIG. Further, when the operator points with the stylus pen 4 on the remaining Y-axis on the screen of FIG.
As shown in (D), a scale is set for this Y axis as well, and it is highlighted, and the setting of the scales for the X axis and the Y axis is completed on this screen.

Next, in order to input the coordinate values for drawing the line graph, the operator sets the position on the X coordinate axis corresponding to the X coordinate value of the points forming the graph as shown in FIG. 7 (A) with the stylus pen. When the instruction is given in step 4, the indicated numerical value is displayed in the area 62, and the straight line 63 parallel to the Y axis is displayed as shown in the figure. At this time, since the coordinate values input in the area 62 are displayed as described above, the operator can know the position of the input point in real time. Next, when the operator designates the Y-axis coordinate value of the input point with the stylus pen 4 as shown in FIG. 7B, the designated value on the Y-axis is displayed in the area 68 in the same manner as described above. At the same time, a straight line 64 parallel to the X axis is displayed, and an intersection point 65 of the two displayed straight lines is displayed. After sequentially inputting coordinate points as described above, selecting “confirm” on the menu bar 61 with the stylus pen 4 displays a straight line connecting the input intersections, as shown in FIG. 8C. Become. After inputting the intersection point 66 by performing the same operation as described above in FIG. 8 (C) and selecting “confirm” on the menu bar 61 with the stylus pen 4, the “confirm” is highlighted and then As shown in FIG. 8 (D), the intersection point 66 and the intersection point 65 input immediately before the intersection point 66 are connected and displayed by a straight line 67, and the line graph is completed. As described above, when the stylus pen 4 is used to point the display input surface 12, that is, the tablet 6, and the coordinate value of each point forming the line graph is input, the CPU 1 changes the pointing position of the stylus pen 4. If you input it through the tablet control unit 7, X
It is converted into numerical values on the axes and the Y-axis, and these numerical values (X coordinate value and Y coordinate value) are stored in the main memory 2 as data of the input points forming the line graph. At the same time, the CPU 1 converts the coordinate value corresponding to the numerical value into the coordinate value of the LCD 8, further converts the coordinate value into the corresponding address of the bitmap memory 10, and the address on the bitmap memory 10 is "1". By writing, the intersection 6 on the LCD 8
5, 6, etc. are displayed.

9 and 10 show a method of directly inputting the position of each point constituting the line graph by the stylus pen 4 to the display input surface 12 unlike the above-described method of inputting the line graph. .. In this method, as shown in FIGS. 7 and 8, the position of the input point is not input by designating the X coordinate and the Y coordinate value of the input point as the X coordinate and the coordinate point corresponding to the Y coordinate axis. This is a method of directing with the stylus pen 4. The operator inputs points on the screen, which are nodes of the line graph, by directly pointing the corresponding position on the display input surface 12 with the stylus pen 4. As a result, the CPU 1 displays a point at the position designated by the stylus pen 4 and a straight line connecting the points, as shown in FIG. 9A. 72 is a straight line displayed in this way. Here, the operation of inputting the third point using the stylus pen 4 will be described in detail. First, when a straight line of a is written using the stylus pen 4 at a position corresponding to the Y coordinate of the point to be input, FIG. As shown, the Y coordinate value at that time is displayed in the area 73. After that, when a straight line is drawn at a position corresponding to the X coordinate of the point, the X coordinate value at that time is displayed in the area 74 as shown in FIG. Thus, when the X coordinate and the Y coordinate are designated by + as described above, a point is input at the position of the intersection, as shown in FIG. 9B, and then this point and the point immediately before that point are input. A straight line 75 connecting the points is displayed. The CPU 1 determines the coordinate value of the pointing point of the stylus pen 4 of the tablet 6 by the tablet control unit 7.
The input coordinate values are converted into coordinate values on the graph and then stored in the main memory 2. By the above-described operation, after the line graph is displayed on the display input surface 12 as shown in FIG. 10C, when "confirm" on the menu bar 71 is selected with the stylus pen 4, "confirm" is displayed.
Is highlighted and a pop-up menu 76 is displayed. The operator has this popup menu 76
When the item of "save" is selected from among the items with the stylus pen 4, this "save" is highlighted and the input menu 77 for displaying the file name is displayed as shown in FIG. 10 (D). .. Therefore, when the operator handwrites the file name with the stylus pen 4, the CPU 1 character-recognizes the handwritten character input by the handwritten character recognition function and displays the recognition result on the display input unit 12. After that, the CPU 1 reads out the data of the line graph currently displayed on the main memory 2 from the main memory 2 and stores it in the external storage device 3.

Next, an example of creating a table corresponding to the line graph drawn as described above will be described. In this case as well, first, as shown in FIG. 11A, the initial screen is displayed on the display input unit 12, and the operator selects "Create table" of the pop-up menu 81 of this screen with the stylus pen 4, and the "Create table" is displayed. Is highlighted. When the "table creation" is selected as described above, the CPU 1 "opens" an existing file, "is it new", as shown in FIG.
Popup menu 82 for the operator to select
Is displayed on the display input screen. Therefore, when the operator selects a file named "sample" in the pop-up menu 82 from the stylus pen 4, the file name "sample" is highlighted. CPU1
In response to this, the line graph data stored under the file name "sample" is read from the external storage device 3, loaded into the main memory 2, and converted into a table format, and then the display control is performed. LCD 8 via section 9
It is displayed as shown in FIG. This table corresponds to the line graph shown in FIG. 10D, and is a graph drawn by directly inputting points on the display input surface using the stylus pen 4. The operator looks at this table and directly inputs the numerical value to be changed with the stylus pen 4 into the corresponding portion of the table by handwriting, and the CPU 1 recognizes the character and changes the numerical value as indicated by 83 in FIG. 12 (D). Is displayed in the corresponding portion in the table, and the data in the corresponding portion of the main memory 2 is rewritten to the changed numerical value. As a result, when the CPU 1 displays the graph corresponding to the corrected table data again on the display input surface 12,
The changed line graph will be displayed.

Here, the CPU 1 inputs a point designated by the stylus pen 4 from the tablet 6 forming the display input surface 12, and the input point forms an LC forming the display input surface 12.
The operation of displaying on D8 will be outlined according to the flowchart of FIG. First, in step 901, the CPU
1 inputs the X and Y coordinate values (coordinates on the tablet) of the point designated by the stylus pen 4 on the doublet 6 via the tablet control unit 7, and then the CPU 1 outputs these coordinate values on the graph. And stores it in a predetermined area of the main memory 2. At the same time, the CPU 1 converts the input coordinate values (coordinates on the tablet) into corresponding coordinate values on the screen of the LCD 8 by a predetermined calculation formula in step 902 to obtain display coordinate values on the screen of the LCD 8. After that, the process proceeds to step 903. CPU1 is step 903
The display coordinate value on the screen of the LCD 8 is converted into a coordinate value on the bit map memory 10 for writing in the bit map memory 10 by using a predetermined calculation formula, and the bit map memory corresponding to the obtained coordinate value. In step 904, the input point is written in the address above 10. This allows
The display control unit 9 displays the points written on the bitmap memory 10 on the LCD 8. By such an input point display operation, a point is displayed at the same position on the LCD 8 as the position on the tablet 6 designated by the stylus pen 4, and it is as if the stylus pen 4 displayed the input surface 12
It will appear to the operator as if the point had been written in.

FIG. 14 is a diagram for explaining the structure of table data handled by the device shown in FIG. The frame indicated by 101 in FIG. 14A is a display effective area of the LCD 8, and various displays can be performed in this area. On the other hand, the frame of the horizontal axis and the vertical axis shown by 102 is an effective area on the graph, and various graphs are displayed in this area. Again 1
The points indicated by 03 and 104 are coordinate points input by the stylus pen 4, but in this case, they are coordinate points on the tablet 6. 10B is an example of a coordinate point file storing the coordinate points on the tablet 8 designated in FIG. 14A, and FIG. 6 is an example of a data file in which coordinate points on a graph corresponding to the coordinate points on 6 are stored. FIG. 14B is an attribute file, which is a file in which the attributes of the input coordinate points described above (units indicated by the X and Y axes, data necessary for creating a scale etc. table) are stored. FIG. 14C shows FIG.
This is a display example of coordinate points on the graph corresponding to the contents of the data file of (II) of (B), but this is the same as the coordinate points on the tablet 6 shown in FIG. 14 (A). ,
Only the criteria for expressing one coordinate point are different.

FIG. 15 is a flow chart showing the procedure for making a graph using the apparatus shown in FIG.
First, the CPU 1 displays an initial screen on the LCD 8 and allows the operator to select graph creation or table creation. Therefore, the operator determines in step 121 whether to create a graph or a table. When creating a table, the process proceeds to step 137, and when creating a graph, step 1
Proceed to 22. In step 122, the operator selects whether to newly create a graph or expand an existing file to display the graph, and further selects a graph type in step 123 and proceeds to step 124. As a result, if it is determined in step 124 that it is newly created, the process proceeds to step 125, and if it is determined that it is not newly created, the process proceeds to step 129. In step 125, the units for the X and Y axes that define the area for displaying the graph, the scale, etc. are set, and then the process proceeds to step 126. As a result, step 12
At 6, it is determined whether the stylus pen 4 is used to instruct the input mode for instructing the X-axis and Y-axis, or the direct input point is instructed. When the other coordinate designation input mode is adopted, the process proceeds to step 127. In step 127, the coordinate values corresponding to the input points on the X and Y axes are designated by the stylus pen 4 to input one point on the graph, and then the process proceeds to step 128. The operator determines in step 128 whether the graph is completed. If the graph is not completed, the process returns to step 126, and if the graph is completed, the process proceeds to step 134.

On the other hand, when the operation proceeds to step 132, the operator directly points the input point with the stylus pen 4 to input the coordinates into the input display unit 12, and then proceeds to step 133. In step 133, it is judged whether or not the graph is completed. If not completed, the process returns to step 126, and if completed, the process proceeds to step 134. When the process proceeds to step 134, it is determined whether to save the completed graph,
If not saved, the process returns to step 121, and if saved, the process proceeds to step 135. In step 135, select the "File" icon on the screen with the stylus pen 4,
After selecting "Save" of the same icon, enter the file name to save with the stylus pen, and then click Step 136.
Proceed to, save the graph here and return to step 121.

On the other hand, in the case of proceeding to step 129, if the operator specifies the file name to be called, step 1
At 30 the graph stored under the file name is displayed on the display input unit 12. Therefore, in step 131, the operator determines whether to add or correct the displayed graph. If nothing is done, the process proceeds to step 134, and if additional recording or correction is performed, the process proceeds to step 125.

When the operation proceeds to step 137, the operator selects whether to newly create a table or to call the data of the graph from the file and input the file name for displaying the corresponding table. as a result,
If it is determined in step 138 that it is not new creation, the process proceeds to step 142, and if it is determined that it is new creation, the process proceeds to step 139. In step 139, the device is in the table creation mode, so the operator creates a table using the stylus pen 4, and proceeds to step 140. Step 1
At 40, it is determined whether or not to save the created table. If not saved, the process returns to step 121. If saved, the process proceeds to step 141. In step 141, the icon “file” is selected, the icon “save” is selected, the file name to be saved is input with the stylus pen 4, and the displayed table data is saved.
Return to 1. On the other hand, when the operation proceeds to step 142, when the file name called by the operator is designated using the stylus pen 4, the device enters the display mode in step 143, and the table corresponding to the graph of the specified file name is displayed on the display input unit 12 Displayed in. Therefore, the operator determines whether to add or correct the table displayed in step 144, and if nothing is done, the operator proceeds to step 140,
If additional recording or correction is required, the process proceeds to step 139.

According to the present embodiment, the stylus pen 4 inputs the coordinate value of the position of each point forming the graph to the device from the display input surface 12, or the position of each point forming the graph is input to the stylus pen 4. It is not necessary to use a table creation tool such as a spreadsheet for creating a graph as in the conventional art, since the data can be directly input to the device by instructing the display on the input surface 12, and the graph can be displayed according to the image of the operator. It can be created easily and easily. Therefore, the operator can immediately recognize an erroneous input or the like, and the graph once created can be easily added or corrected on the display / input device 12 by using the stylus pen 4. Further, in this example, it is also possible to display the graph created by inputting from the display input surface 12 using the stylus pen 4 as described above as table data, and to add or correct to the table data. Consistency can also be obtained. In the above embodiment, the stylus pen 4 is used to display the display input screen 1
Although the example of creating a graph by inputting each point of the line graph from 2 has been described, various graphs such as a bar graph and a radar chart can be similarly created.

[0025]

As described above, according to the graph creating apparatus of the present invention, the positions of the numerical values or the points forming the graph are displayed on the screen without creating the numerical values for expanding the graph as table data in advance. A graph can be created and displayed by directly inputting with a stylus pen or the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a graph creating apparatus of the present invention.

FIG. 2 is a diagram showing an example of an external appearance of the graph creating apparatus shown in FIG.

FIG. 3 is a diagram showing a configuration of a display input surface shown in FIG.

FIG. 4 is a diagram illustrating an example of an initial screen displayed when a graph is created on the display input surface shown in FIG.

5 is a graph for creating a graph by the apparatus shown in FIG.
The figure which showed the example of a screen for setting the unit of an axis, a Y-axis, the number of divisions of the scale, etc.

FIG. 6 is a graph X when preparing a graph by the apparatus shown in FIG.
The figure which showed the example of a screen for setting the unit of an axis, a Y-axis, the number of divisions of the scale, etc.

FIG. 7 is a diagram showing an example of a screen when the coordinates of each point forming a graph are directly input from the display input surface to create using the stylus pen shown in FIG.

FIG. 8 is a diagram showing an example of a screen when the coordinates of respective points forming a graph are directly input from a display input surface to create using the stylus pen shown in FIG.

9 is a diagram showing a method of directly displaying each point forming a graph on the display input screen by the stylus pen shown in FIG.

10 is a diagram showing a method of directly displaying each point forming a graph on the display input screen by the stylus pen shown in FIG.

FIG. 11 is a diagram showing an example of a screen when displaying and correcting table data corresponding to a graph already created.

FIG. 12 is a diagram showing an example of a screen when displaying and correcting table data corresponding to a graph already created.

13 is a flowchart showing a procedure of a coordinate conversion process until a point designated by a stylus pen on a display input surface is displayed by the device shown in FIG.

FIG. 14 is a diagram for explaining the structure of table data handled by the device shown in FIG.

15 is a flowchart showing a procedure for creating a graph using the apparatus shown in FIG.

[Explanation of Codes] 1 ... CPU 2 ... Main memory 3 ... External storage device 4 ... Stylus pen 5 ... Stylus control unit 6 ... Tablet 7 ... Tablet control unit 8 ... LCD 9 ... Display control unit 10 ... Bit map memory

Claims (2)

[Claims] 1. A graphic creation device equipped with a display input device capable of inputting data from a screen for displaying characters and graphics using a pen or the like, wherein attribute data for creating a graph is input using the pen. And a reference axis for creating a graph on the basis of the attribute data input by the pen from the screen displayed by the attribute data setting means. Graph data input means for displaying a graph creation area on the screen, and numerical value input means for inputting a numerical value corresponding to the position designated by the pen on the reference axis displayed on the screen by the graph data input means , Of the type specified by the attribute data in the graph creation area on the screen based on the numerical value input by the numerical value input means. A graph creating device comprising: a graph creating means for creating and displaying a graph. 2. A graphic creation device equipped with a display input device capable of inputting data from a screen displaying characters and graphics using a pen or the like, and inputting attribute data for creating a graph using the pen. And a reference axis for creating a graph on the basis of the attribute data input by the pen from the screen displayed by the attribute data setting means. Graph data input means for displaying a graph creation area on the screen, and coordinate data corresponding to a position designated by the pen in the graph creation area displayed on the screen by the graph data input means are input. Based on the position input means and the coordinate data input by the position input means, the attribute data is stored in the graph creation area on the screen. A graph creating apparatus comprising: a graph creating unit that creates and displays a specified type of graph.