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Sigma Magic Help Version 17

Network Plot

Overview

Network plot is a powerful graphical technique that helps us understand the complex interrelationships between several factors. It helps us understand the significance of relationships between entities rather than viewing them as isolated entities. The entities are called nodes or vertices of a graph, and the connections are called edges. The data needs to be in a particular format to create a network graph. An adjacency matrix is a square matrix in which the column and row names are the network nodes. Within a matrix, one indicates a connection between the nodes, and 0 indicates no connection. An edge list is a data frame containing at least two columns. One column of nodes is for the source, and the other is for the connection's target. Unique IDs identify the nodes in the data. The network can be directed or undirected. An edge list can also contain additional columns describing the edges' attributes, such as magnitude for weighted graphs.

To add the Network Plot template to your worksheet, click on Analytics and then select Graphs > Network Plot.

Inputs

Click on Analysis Setup to open the menu options for this template. A sample screenshot of the menu is shown below: Network Plot Menu 1
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Data Type: Specify the data type that is used to generate the network plot.
OptionDescription
AdjacencySpecify the adjacency matrix for the network plot. An adjacency matrix is a square matrix between nodes with 0's and 1's. A 0 indicates that there is no connection between the nodes, and a value of 1 indicates that there is a connection between the nodes.
IncidenceAn incidence matrix is a matrix that shows the relationship between two classes of objects. An incidence matrix does not have to be square and shows the relationship between two vectors of different lengths. If the first class is X and the second is Y, the matrix has one row for each element of X and one column for each element of Y. The entry in row x and column y is one if x and y are related (called the incident in this context) and 0 if they are not.
Edge ListAn edge list is a table that contains a minimum of two columns. One column of nodes is for the source, and the other is for the connection's target.
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Num Columns: You can specify the number of input variables you want to analyze for this analysis. The current version of the software will let you analyze up to 30 variables.
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Mode: Specify the type of graph you want to create.
OptionDescription
UndirectedThis is used to create a network graph that is not directed. In this case, all the edges are bi-directional.
DirectedIn a directed graph, the direction of connection between the nodes has a specific meaning. For example, the graph can only be traversed from A to B and not from B to A.
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Layout: Specifies how the graph needs to be arranged. The following options are available:
OptionDescription
SphereThe nodes of the graph are spread out so that they fall on a sphere.
CircleThe nodes of the graph are spread out so that they fall on a circle.
RandomThe nodes of the graph are randomly placed.
Fruchterman ReingoldThis approach tries to place the nodes in such a way as to minimize edge crossing and overlaps.
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Additional Options: This field is optional. By typing it here, you can specify any additional options for the R software program.
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Help Button: Click on the Help Button to view the help documentation for this template.
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Cancel Button: Click on the Cancel Button to discard your changes and exit this menu.
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OK Button: Click on the OK Button to save your changes and try to execute the program. Note that you must specify what is required to complete the analysis and generate outputs. If there are any missing data, the software will remind you to specify the data and click on Compute Outputs to generate analysis results.

Data

You will see the following dialog box if you click the Data button. Here, you can specify the data required for this analysis. Data
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Search Data: The available data displays all the columns of data that are available for analysis. You can use the search bar to filter this list and speed up finding the right data for analysis. Enter a few characters in the search field, and the software will filter and display the filtered data in the Available Data box.
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Available Data: The available data box contains the list of data available for analysis. If your workbook has no data in tabular format, this box will display "No Data Found." The information displayed in this box includes the row number, whether the data is Numeric (N) or Text (T), and the name of the column variable. Note that the software displays data from all the tables in the current workbook. Even though data within the same table have unique column names, columns across different tables can have similar names. Hence, it is crucial that you not only specify the column name but also the table name.
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Add or View Data: Click on this button to add more data to your workbook for analysis or to view more details about the data listed in the available data box. When you click on this button, it opens the Data Editor dialog box, where you can import more data into your workbook. You can also switch from the list view to a table view to see the individual data values for each column.
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Required Data: The code for the required data specifies what data can be specified for that box. An example code is N: 2-4. If the code starts with an N, you must select only numeric columns. If the code begins with a T, you can select numeric and text columns. The numbers to the right of the colon specify the min-max values. For example, if the min-max values are 2-4, you must select a minimum of 2 columns of data and a maximum of 4 columns in this box. If the minimum value is 0, then no data is required to be specified for this box.
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Select Button: Click on this button to select the data for analysis. Any data you choose for the analysis is moved to the right. To select a column, click on the columns in the Available Databox to highlight them and then click on the Select Button. A second method to choose the data is to double-click on the columns in the list of Available Data. Finally, you can drag and drop the columns you are interested in by holding down the select columns using your left mouse key and dragging and dropping them in one of the boxes on the right.
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Selected Data: The list box header will be displayed in black if the right number of data columns is specified. If sufficient data is not specified, the list box header will be displayed in red. Note that you can double-click on any of the columns in this box to remove them from the box.
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View Selection: Click on this button to view the data specified for this analysis. The data can be viewed in a tabular format or a graphical summary of the selected data.

Verify

If you click the Verify button, the software will perform some checks on the data you entered. A sample screenshot of the data is shown in this figure. Pre-Process Inputs 4
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Verify Checks: The software checks if you have correctly specified the input options and if you have specified the data correctly for analysis.
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Check Status: The results of the analysis checks are listed here. If the checks are passed, they are shown as a green checkmark. If the verification checks fail, they are shown as a red cross. If the verification checks result in a warning, they are shown in the orange exclamation mark. Finally, any checks that are required to be performed by the user are shown as blue info icons.
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Overall Status: The overall status of all the checks for the given analysis is shown here. The overall status check shows a green thumps-up sign if everything is okay and a red thumps-down sign if any checks have not passed. Note that you cannot proceed with generating analysis results for some analyses if the overall status is not okay.

Outputs

Click on Compute Outputs to generate the outputs from this analysis. A sample screenshot of the worksheet is shown below. Example Network Plot
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Notes Section: The notes section summarizes the inputs used for creating the network plot. No specific analysis is displayed in this section.
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Graph Section: The graph section shows the generated network plot.

Notes

Here are a few notes regarding this analysis:
  • If you want to review the R program used to generate this output, go to the %TMP%/Sigma Magic/ folder and look for the file smRScript.R after executing the program. This folder contains other files, such as error or warning output, text, and graphical output from running R. However, these files are stored temporarily and are not persistent between sessions.

Examples

The following examples are in the software's Examples folder.
  • Create a Network Plot for the data shown in the examples folder (Network Plot 1.xlsx).

References

For more information on this topic, please refer to the following articles. Do note that if any external links are mentioned below, they are for reference purposes only.


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