JP3209387B2 - Node optimal arrangement method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a network configuration display system for displaying a logical connection status between nodes which are network components in a communication network, a power system, a gas pipeline network, a water network or the like. The present invention relates to an optimal node arrangement method and apparatus for converting a map coordinate into a logical coordinate while preserving a relative positional relationship between map coordinates in the real world indicating a connection state between nodes and without overlapping the nodes.

[0002]

2. Description of the Related Art In this type of network configuration display system,
For example, in a conventional communication network configuration display system for a communication network, all node elements constituting the communication network are displayed in proportion to map elements in their entirety, and the network configuration is performed by a partial enlargement / reduction operation by a user's screen operation. Some of the elements are highlighted.

On the other hand, a system is realized in which a subset of network components to be highlighted is extracted from a database, and nodes are optimally arranged on logical coordinates in a display space based on a relative positional relationship between map coordinates of the subset. ing. In such a system, the conversion from map coordinates to logical coordinates is performed by calculating the logical coordinates by dividing the map coordinates by the ratio of the space between the map coordinates and the logical coordinates without checking for the presence of node overlap. I have. For this reason, nodes in a geographically dense node area such as an urban area cause overlapping node coordinates on logical coordinates.

Conventionally, this node duplication is a process of calculating a node density distribution on a sub logical coordinate space obtained by dividing a logical coordinate space, and bringing the node density of the sub logical coordinate space closer to the average density (density distribution uniforming process). Automatic means such as moving nodes in the direction of the difference in map coordinates between overlapping nodes (node adjacent coordinate movement processing) or manual moving means in which a user directly designates a destination by means of interactive node duplication. Has been eliminated.

[0005]

In the above-mentioned conventional density distribution equalizing process, depending on the balance of the density distribution of the nodes, a process of rearranging the entire space may be caused as a result. Is difficult and requires a lot of processing time. In addition, in the node adjacent coordinate movement processing in a very close range, there may be a case where a part of the relative relationship between the node coordinates cannot be saved, and it is necessary to always check whether or not the nodes overlap after the node arrangement processing. .

Therefore, in order to confirm the result of the coordinate conversion,
There is a problem that it always requires the intervention of the user, and continuous automatic processing of the node arrangement and the link display processing cannot be performed.

Furthermore, since the node arrangement processing is performed every time the network component subset is retrieved from the database, there is a problem that the same processing is repeated again for the subset in which the node is not changed.

[0008] The present invention has been made in view of the above,
The goal is to save the map coordinates completely and save the map coordinates in logical coordinates in a fixed processing time without generating node coordinates regardless of the uniformity of the node density distribution. It is an object of the present invention to provide a method and an apparatus for optimally arranging nodes for converting to a node.

[0009]

In order to achieve the above object, a method for optimally arranging nodes according to the present invention comprises a method of extracting network components extracted from all network components stored in a network configuration management database in accordance with user requirements. This is an optimal node placement method for converting the map coordinates to logical coordinates of an arbitrary display space while preserving the geographic relative positions of the real world for the nodes included in the subset. Enlarge to a sufficiently large coordinate space that is not overlapped and displayed, and then calculate the reduction ratio between the X-axis and Y-axis of the real world map coordinates and the logical coordinates of the display space, and use a value smaller than the reduction ratio. X-axis and Y-axis node intervals are alternately and stepwise reduced, and the occurrence of node duplication in the reduction process is checked to eliminate the duplication, and the conversion is repeated up to the target logical coordinate size. And summarized in that the optimal placement on the logical coordinate of the display space more nodes.

[0010] In the above-mentioned method of optimally arranging nodes according to the present invention, the nodes which are optimally arranged on the logical coordinates of the display space are continuously linked using the logical coordinates converted by the node arranging process. The point is to perform an arrangement process.

Further, in the above-described node optimum arrangement method of the present invention, the created node arrangement information is accumulated for each subset of the network components, and each time a search is performed, the addition or deletion of a node and the change in the movement of map coordinates are performed. The gist is to check the presence / absence and to use the accumulated node arrangement information if there is no change.

[0012] The node optimum arrangement device of the present invention provides a real-world geographic relative node for nodes included in a subset of network components extracted according to user requirements from all network components stored in a network configuration management database. An optimal node layout device that converts map coordinates to logical coordinates in an arbitrary display space while preserving positional relationships, and expands the real world map coordinates to a sufficiently large coordinate space where nodes are not displayed redundantly. And a reduction ratio between the X axis and the Y axis of the real world map coordinates and the logical coordinates of the display space, and using a value smaller than the reduction ratio, alternately and stepwise the node intervals between the X axis and the Y axis. Reduction means for reducing the number of nodes in the process of reduction, duplication removal means for checking the occurrence of node duplication in the reduction process, and eliminating duplication. And summarized in that a means for optimal placement on the logical coordinate of the display space.

[0013] In the above-described node optimum arranging apparatus, the nodes which are optimally arranged on the logical coordinates of the display space are continuously linked using the logical coordinates converted by the node arranging process. The gist of the invention is to have means for performing the arrangement processing.

Further, the node optimum arrangement apparatus of the present invention stores the created node arrangement information for each subset of the network components, and adds / deletes nodes and changes in the movement of map coordinates each time a search is performed. It has a means for checking the presence or absence, and when there is no change, the gist is to use the accumulated node arrangement information.

The node optimum arranging apparatus of the present invention converts a real world map coordinate indicating a connection state between nodes into a logical coordinate while maintaining the relative positional relationship of the map coordinates without overlapping each other. An optimal placement device that checks for duplicate map coordinates and uses the specified information source to completely eliminate duplicate node coordinates, regardless of the uniformity of the node density distribution. Means for eliminating the duplication of the nodes by enlarging the map coordinates, means for alternately reducing the node interval of the enlarged map coordinates with respect to the X coordinate axis and the Y coordinate axis, and checking the duplication of the nodes after the reduction. The gist of the present invention is to have a means for eliminating node duplication, a means for checking whether or not a node has reached a target logical coordinate space, and a means for performing a link arrangement process after executing a node arrangement process. .

[0016]

According to the node optimum arranging method of the present invention, the map coordinates of the real world are enlarged to a sufficiently large coordinate space where the nodes are not displayed redundantly, and the map coordinates of the real world and the logical coordinates X of the display space are enlarged. Calculating a reduction ratio between the axis and the Y-axis, reducing the interval between the nodes on the X-axis and the Y-axis alternately and stepwise by using a value smaller than the reduction ratio, removing overlapping nodes in the reduction process;
The node is optimally arranged on the logical coordinates of the display space by repeating the conversion up to the size of the target logical coordinates.

Further, in the node optimum arrangement method of the present invention,
In the above, link arrangement processing is continuously performed between nodes optimally arranged on the logical coordinates of the display space using the logical coordinates converted by the node arrangement processing.

Further, in the node optimum arrangement method of the present invention,
In the above, the created node arrangement information is accumulated, and every time a search is performed, the presence or absence of a change in the addition or deletion of a node and the movement of the map coordinates is checked. If there is no change, the accumulated node arrangement information is used.

In the node optimum arranging apparatus of the present invention, the map coordinates of the real world are enlarged to a sufficiently large coordinate space where the nodes are not displayed redundantly, and the map coordinates of the real world and the X of the logical coordinates of the display space are enlarged. The reduction ratio between the X-axis and the Y-axis is obtained, the node interval between the X-axis and the Y-axis is reduced alternately and stepwise by using a value smaller than the reduction ratio, the overlap of the nodes in the reduction process is removed, and the target logical coordinates The node is optimally arranged on the logical coordinates of the display space by repeating the conversion up to the size of.

Further, in the node optimal arrangement device of the present invention,
In the above, link arrangement processing is continuously performed between nodes optimally arranged on the logical coordinates of the display space using the logical coordinates converted by the node arrangement processing.

Further, in the node optimum arrangement device of the present invention,
In the above, the created node arrangement information is stored for each subset of the network components, and each time a search is performed, means for checking whether there is a change in addition, deletion and movement of the map coordinates are provided. Uses the accumulated node arrangement information.

In the node optimum arranging apparatus of the present invention, the duplication of the given map coordinates is checked, the node duplication is eliminated by enlarging the map coordinates, and the node interval of the enlarged map coordinates is set to the X coordinate axis and the Y coordinate. The coordinate axes are alternately reduced, overlapping of the nodes after the reduction is eliminated, it is checked whether or not the target logical coordinate space has been reached, and after the node arrangement processing is performed, the link arrangement processing is performed.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a network configuration display system to which a node optimal arrangement method according to one embodiment of the present invention is applied. The network configuration display system shown in FIG. 1 is applicable to a communication network, an electric power system, a gas pipeline network, a water network, and the like. In the present embodiment, an example in which the invention is applied to a communication network will be described.

The network configuration display system shown in FIG. 1 includes a database search unit 101, a graphic information creating unit 102, and a graphic display unit 103. The database search unit 101 includes a search condition input processing unit 104 for inputting search conditions from a user, and the network configuration management database 10 according to the search conditions input from the search condition input processing unit 104.
6 and a network configuration management database 106. Further, the graphic information creating unit 102 receives the graphic optimum display information 107 including the map coordinate information of the nodes in the real world and the search result display target information 110 from the database search unit 101, and receives the node optimal arrangement processing unit 108 and the link. It comprises an optimal arrangement processing unit 109. The network configuration display information 111 from the graphic information creating unit 102 is input to the graphic display unit 103 and is displayed on the graphic display unit 103. It is assumed that the graphic display unit 103 uses any existing tool that can display a drawing by specifying coordinates and an object.

FIG. 2 is a flowchart showing main processing of the network configuration display system shown in FIG. The processing flow of the network configuration display system shown in the figure includes a network configuration search process 201 that is interactively activated by a user's request, and the network configuration search process 201 is activated, and is activated every time a new display target is retrieved. Node arrangement processing 202 and link optimal arrangement processing 2 for automatically displaying a new network configuration.
03.

More specifically, in the processing of the network configuration display system shown in FIG. 2, first, it is waited for a new search request from the user (step 211). Is set (step 213), and the network configuration management database 106 is searched based on the search condition (step 2).
15).

Then, the display target information 11 of this search result is displayed.
When “0” is input to the node optimal arrangement processing unit 108 together with the graphic display basic information 107, the node optimal arrangement processing unit 1
08 executes the node optimum arrangement processing 202. In this process, as will be described later, first, a difference from the already created node arrangement is checked (step 221), and then the X coordinate is converted at a fixed ratio (step 222), and the Y coordinate is converted at a fixed ratio (step 223). ). Then, it is checked whether or not the data has been converted to the target size by this conversion (step 224). If the data has not been converted to the target size, the process returns to step 222 to be converted to the target size. Until the conversion process of steps 222 and 223 is repeated until the target size is obtained, the node arrangement result is accumulated (step 225).

Next, the link optimal arrangement processing unit 109 creates shortest path data between nodes based on the node arrangement result from the node optimal arrangement processing unit 108 (step 23).
1), line segment avoidance connection point data is created (step 233). Then, the network configuration display information 111 thus created is displayed on the graphic display unit 103 (step 235).

FIG. 3 is a diagram showing an outline of the coordinate conversion processing of the node arrangement. In this figure, hatched circles indicate nodes, but display target node groups 302 and 303 are selected from all the nodes on the map coordinate space 301, and the display destination logical coordinate spaces 304, 305 and 306 are selected. When set,
While preserving the relative positional relationship between the display target node groups, the map coordinates are converted into logical coordinates, and the display space A30 is displayed.
7, B308, and B309. When the coordinates are enlarged as in the logical coordinate space 306, the coordinates of the nodes do not overlap, and can be easily obtained by multiplying the map coordinates by the enlargement ratio between the map coordinates and the logical coordinates. The node optimal arrangement method of the present invention is particularly related to the case of coordinate reduction in which there is a possibility that node coordinate duplication may occur in coordinate transformation as in the logical coordinate spaces 304 and 305.

FIG. 4 is a flowchart showing a node arrangement information creating process in the node optimal arrangement method of the present embodiment. The node arrangement information creation processing shown in FIG. 9 includes a difference check processing 401 with the already created node arrangement, a map coordinate duplication elimination processing 402, a coordinate reduction conversion processing 403, a coordinate enlargement conversion processing 404, a node arrangement result storage processing 405, and an existing arrangement. It has a node placement result quoting process 406.

More specifically, in the node arrangement information creation processing shown in FIG. 4, first, a target subset number of a database (DB) search is obtained (step 411), and then a node arrangement result of the same subset number is obtained (step 411). 412), adding a node in the subset from both,
A difference such as deletion is detected (step 413), and it is checked whether a node is added or deleted (step 41).
4). As a result, if there is no addition or deletion of nodes,
Referring to the existing node arrangement result (step 461),
The process is terminated, but if there is addition or deletion, it is first checked whether or not the actual coordinates are larger than the logical coordinates (step 420).

If the real coordinates are not greater than the logical coordinates,
That is, when the logical coordinates are larger than the actual coordinates, the coordinate enlargement conversion processing is performed (step 441), the node arrangement result is stored (step 451), and the processing is terminated. If it is larger, map coordinate duplication elimination processing is performed for all nodes (step 42).
1). This map coordinate de-duplication processing is described in FIG.
This will be described in detail.

When the map coordinate duplication elimination processing is completed in step 421, an X coordinate reduction calculation is first performed in order to perform a coordinate reduction conversion processing (step 431), and then a Y coordinate reduction calculation is performed (step 432). Then, it is checked whether the size has been converted to the target size (step 43).
3) If the size has not been converted to the target size, the process returns to step 431 to repeat the same process. If the size has been converted to the target size, a coordinate enlargement conversion process is performed (step 441), and the node The arrangement result is saved (step 451), and the process ends.

Next, the details of the map coordinate duplication elimination processing 402 in the above-described node arrangement information creation processing shown in FIG. 4 will be described with reference to the flowchart shown in FIG. The map coordinate de-duplication process shown in FIG. 5 includes a process 501 for detecting a duplicate node, a process 502 for securing a space at a destination of the duplicate node, and a process 5 for setting a destination coordinate of the duplicate node.
03.

In the map coordinate duplication elimination processing shown in FIG. 5, node coordinate information is sorted using the X coordinate as a primary key and the Y coordinate as a secondary key (step 511). Then, a loop process is set to repeat the subsequent processes, that is, the processes of steps 513 to 533, for all the processing nodes (step 512). Then, the coordinates of the processing node currently being processed are set as processing coordinates (step 513), and the processing node is registered in the overlapping coordinate node table (step 514).

A loop process for repeatedly performing the following steps 516 to 518 is set (step 5).
15) The coordinates of the comparison node currently being processed are set as comparison node coordinates (step 516), and it is checked whether the processing coordinates are equal to the comparison coordinates (step 517). If they are not equal, the process returns to step 515 to repeat the same processing. If they are equal, the comparison node is registered in the overlapping coordinate node table (step 518).

Next, it is checked whether or not the number of registered duplicate nodes is greater than 1 (step 521). If it is not greater than 1, the process is terminated as it is. If it is greater than 1, the process proceeds to step 522, and a loop process for repeating the process of step 523 with N as a variable from 3 to a plurality is set. In step 523, the number of additional XY = duplicate number / N is calculated, and it is checked whether or not the remainder is zero. If the remainder is not 0, the process returns to step 522 to repeat the same process. If the remainder is 0, the process proceeds to step 524.

In step 524, the following steps 525 and 526 are repeated for all the comparison nodes. In step 525, the processing node coordinates are subtracted from the comparison node coordinates to calculate a coordinate difference.
It is checked whether it is greater than (step 526).
If the coordinate difference is not greater than 0, the process returns to step 524 to repeat the same processing. If the coordinate difference is greater than 0, it is checked whether the number of additional XY is greater than or equal to the coordinate difference (step 524). 527). If the additional XY number is smaller than the coordinate difference, the process proceeds to step 531. If the additional XY number is larger than or equal to the coordinate difference, the coordinate of the comparison node is incremented by 1 (step 528).
Proceed to step 531.

In step 531, the duplicate node is extracted from the duplicate coordinate node table, the destination coordinates are set (step 532), the duplicate coordinate node table is reset (step 533), and the process ends.

Next, details of the X coordinate reduction calculation processing of the coordinate reduction conversion processing 403 in the above-described node arrangement information creation processing shown in FIG. 4 will be described with reference to the flowchart shown in FIG. Coordinate reduction conversion processing 403 shown in FIG.
The X coordinate reduction calculation processing includes a new coordinate calculation processing loop 601 for the relevant X axis and a new coordinate setting processing loop 602 for the relevant X axis in a large loop that simultaneously processes the same X coordinate node from small coordinates. The new coordinate calculation processing loop 601 includes a calculation processing 603 of a new coordinate of the corresponding X axis, a jump inspection and update processing 604 regarding a new X coordinate on the same Y axis node,
It has a maximum X coordinate inspection and update processing 605 within the processing range.

The new coordinate calculation process 603 derives the new coordinates by truncating the decimal point of (X coordinate ÷ 2).
Inspection and update processing 604 of the jump X coordinate checks whether or not a node of the same X axis exists between the coordinate before conversion and the coordinate after conversion, and if so, adds the coordinate after conversion to this coordinate + 1. Change to Maximum X coordinate update processing 605
Updates the maximum X coordinate if the converted coordinate is larger than the maximum X coordinate within the processing range. The calculation of the new Y coordinate can be performed by the same processing only by changing the X axis to the Y axis.

FIG. 7 is a flowchart showing details of the new X-coordinate skipping inspection and update processing 604 in the X-coordinate reduction calculation processing of the coordinate reduction conversion processing shown in FIG. In the skip inspection and update process of the new X-coordinate shown in FIG. 7, first, the parameters are initialized, and then the X-coordinate and the Y-coordinate are obtained for all the processing nodes, and whether the obtained Y-coordinate is equal to the comparison Y-coordinate is determined. Check if X
Check whether the coordinate is equal to the old X coordinate, check whether the X coordinate is equal to the comparison X coordinate, and when they are equal, set the value obtained by adding +1 to the X coordinate as the return value. Inherited as a parameter.

FIG. 8 is a flowchart showing details of the maximum X coordinate inspection and update processing 605 within the processing range in the X coordinate reduction calculation processing of the coordinate reduction conversion processing shown in FIG. In the maximum X coordinate inspection and update processing within the processing range shown in FIG. 8, first, parameters are initialized, the X coordinate of the processing node is acquired, and it is checked whether the X coordinate is larger than the comparison X coordinate. It is checked whether or not the coordinates are larger than the return value. If the coordinates are larger, the X coordinate is set as a return value, and the return value is taken over as a parameter.

FIGS. 9 and 10 show how the node coordinates change stepwise when the above-described processing is performed, from the start of conversion of the X coordinate to the end of conversion, and from the start of conversion of the Y coordinate to the end of conversion. FIG.
9 and 10, white circles indicate unconverted nodes, circles with diagonal lines in one direction indicate X-coordinate converted nodes, and circles with cross diagonal lines in both directions indicate X and Y coordinate converted nodes. Is shown. In the conversion of the X coordinate shown in FIG. 9, the X coordinate is reduced from the smaller X coordinate, and the X coordinate is updated. In the conversion of the Y coordinate shown in FIG. The coordinates are reduced and the XY coordinates are converted.

[0045]

As described above, according to the present invention,
The map coordinates of the real world are enlarged to a sufficiently large coordinate space where the nodes are not displayed redundantly, and the reduction ratio between the X-axis and the Y-axis of the real world map coordinates and the logical coordinates of the display space is obtained. The node space is alternately and stepwise reduced by using a value smaller than the ratio in the X-axis and the Y-axis, the duplication of the nodes in the reduction process is removed, and the conversion is repeated to the size of the target logical coordinates, thereby displaying the nodes in the display space. Optimally placed on the logical coordinates of, the processing time is constant regardless of the uniformity of the node density distribution, and node duplication does not occur, so that user intervention can be avoided. Display can be performed, and interactive operation can be performed smoothly.

Further, according to the present invention, the created node arrangement information is accumulated, and every time a search is made, it is checked whether or not there is a change in addition or deletion of a node and the movement of the map coordinates. Using the node placement information
The processing can be performed in a short time without performing the node arrangement processing repeatedly and repeatedly as in the related art.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a network configuration display system to which a node optimal arrangement method according to an embodiment of the present invention is applied.

FIG. 2 is a flowchart showing main processing of the network configuration display system shown in FIG.

FIG. 3 is a diagram illustrating an outline of a coordinate conversion process of a node arrangement.

FIG. 4 is a flowchart showing a node arrangement information creating process in the node optimal arrangement method of the embodiment shown in FIG. 1;

FIG. 5 is a flowchart showing details of a map coordinate duplication elimination process in the node arrangement information creation process shown in FIG. 4;

6 is a flowchart showing details of an X coordinate reduction calculation process of a coordinate reduction conversion process in the node arrangement information creation process shown in FIG.

7 is a flowchart showing details of a new X-coordinate skipping inspection and update process in the X-coordinate reduction calculation process of the coordinate reduction conversion process shown in FIG. 6;

8 is a flowchart showing details of a maximum X coordinate inspection and update process within a processing range in an X coordinate reduction calculation process of the coordinate reduction conversion process shown in FIG.

FIG. 9 is a diagram illustrating a state in which node coordinates change stepwise when the node optimum arrangement processing in the embodiment is performed, from the start of conversion of X coordinates to the end of conversion.

FIG. 10 is a diagram illustrating a state in which node coordinates change stepwise when the node optimum arrangement processing in the embodiment is performed, from the start of conversion of the Y coordinate to the end of conversion.

[Explanation of symbols]

 Reference Signs List 101 Database search unit 102 Graphic information creation unit 103 Graphic display unit 105 Network configuration search processing unit 106 Network configuration management database 108 Node optimal arrangement processing unit 109 Link optimal arrangement processing unit

Continuation of the front page (56) References JP-A-7-79283 (JP, A) Koji Yada, et al., "B-607 Human Machine Interface in Network Configuration Management", 1990 Spring of IEICE. National Conference Lecture Papers 3, 1990, p. 185 (58) Field surveyed (Int. Cl. ⁷ , DB name) G06F 17/50 G09G 5/36 H04M 3/00 G06F 17/30 JICST file (JOIS)

Claims (6)

(57) [Claims] 1. A map for a node included in a subset of network components extracted from all network components stored in a network configuration management database according to a user's requirement while preserving a relative geographical positional relationship in the real world. This is an optimal node arrangement method for converting coordinates into logical coordinates in an arbitrary display space. First, the map coordinates of the real world are enlarged to a sufficiently large coordinate space where nodes are not displayed redundantly, The reduction ratio between the X-axis and the Y-axis of the world map coordinates and the logical coordinates of the display space is obtained, and the node interval between the X-axis and the Y-axis is reduced alternately and stepwise by using a value smaller than the reduction ratio. Nodes characterized by optimally arranging nodes on logical coordinates in a display space by checking occurrence of node duplication in the process, eliminating the duplication, and repeating the conversion until the size of the target logical coordinates. Optimal placement method. 2. A link arrangement process is continuously performed between nodes optimally arranged on logical coordinates in a display space using the logical coordinates converted by the node arrangement process. Node optimal placement method described. 3. The created node arrangement information is stored for each subset of network components, and each time a search is performed, the presence or absence of a change in the addition or deletion of a node and the movement of map coordinates is checked. 2. The node optimum arrangement method according to claim 1, wherein the obtained node arrangement information is used. 4. Nodes included in a subset of network components extracted according to user requirements from all network components stored in a network configuration management database are stored in the map while preserving the geographical relative positional relationship in the real world. An optimal node arranging apparatus for converting coordinates into logical coordinates in an arbitrary display space, the enlargement means for enlarging map coordinates of the real world to a sufficiently large coordinate space in which nodes are not displayed redundantly. And Y coordinates of map coordinates and logical coordinates of display space
Calculate the reduction ratio of the axis, and use a value smaller than the reduction ratio to obtain X
Reducing means for alternately and stepwise reducing the node interval between the axis and the Y-axis; overlapping removing means for checking the occurrence of node duplication in the shrinking process to eliminate duplication; and repeating the conversion to the size of the target logical coordinates Means for optimally arranging the nodes on the logical coordinates of the display space according to the following. 5. A method for continuously arranging links between nodes optimally arranged on logical coordinates in a display space using the logical coordinates converted by the node arrangement processing. The node optimal arrangement device according to claim 4. 6. A means for accumulating the created node arrangement information for each subset of the network components, and checking for addition / deletion of a node and a change in movement of map coordinates every time a search is performed. 5. The node optimum placement device according to claim 4, wherein the stored node placement information is used in such a case.