Help Manual

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• Lean Templates
• Graph Templates
• Projects Templates
• Stats Templates
• Active Worksheet
• Miscellaneous

Sigma Magic Help Version 15

Network Plot

Overview

Network Plot is a powerful graphical technique to 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 referred to as nodes or vertices of a graph, and the connections are called edges. To create a network graph, the data needs to be in a particular format. An adjacency matrix is a square matrix in which the column and row names are the nodes of the network. Within a matrix, 1 indicates that there is a connection between the nodes, and 0 indicates no connection. An edge list is a data frame that contains a minimum of two columns. One column of nodes is for the source, and the other column of nodes is for the target of the connection. The nodes in the data are identified by unique IDs. The network can be directed or undirected. An edge list can also contain additional columns that describe attributes of the edges, 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:
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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 1 if x and y are related (called 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 for the source and the other column of nodes for the target of the connection.
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Num Columns: You can specify the number of input variables that you would like 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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Vertex: Specify any options to use for the vertex.
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Vertex Label: Specify any options to use for the vertex labels.
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Edge: Specify any options to use for the edges.
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Additional Options: This field is optional. You can specify any additional options for the R software program directly by typing it here.
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Help Button: Click on the Help Button to view the help documentation for this template.
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OK Button: Click on the OK Button to save your changes and try to execute the program. Note that you will need to specify the required data in order to complete the analysis and generate outputs. If there are any missing data, then the software will remind you to specify the data and click on Compute Outputs to generate analysis results.

Data

If you click on the Data button, you will see the following dialog box. Here you can specify the data required for this analysis.
 1 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 to speed up finding the right data to use 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. 2 Available Data: The available data box contains the list of data available for analysis. If your workbook does not have any 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 important that you not only specify the column name but also the table name. 3 Add or View Data: Click on this button either to add more data into 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 up the Data Editor dialog box where you can import more data into your workbook, or you can switch from the list view to a table view to see the individual data values for each column. 4 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, then you will need to select only numeric columns. If the code starts with a T, then you can select both 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, then you need to select a minimum of 2 columns of data and a maximum of 4 columns of data in this box. If the minimum value is 0, then no data is required to be specified for this box. 5 Select Button: Click on this button to select the data for analysis. Any data you select 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 select the data is to double click on the columns in the list of Available Data. Finally, you can also 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. 6 Selected Data: If the right amount of data columns has been specified, the list box header will be displayed in the black color. If sufficient data has not been specified, then the list box header will be displayed in the red color. Note that you can double-click on any of the columns in this box to remove them from the box. 7 View Selection: Click on this button to view the data you have specified for this analysis. The data can be viewed either in the tablular format or you can view a graphical summary of the data selected.

Program

If you click on the Program button, the software will display the program code - an example screenshot is shown in the figure below.
 1 R Program: You can view the R program that will be executed here. This program is usually automatically generated from the options you have specified in the setup earlier. This is the program that will be executed by the R program to generate analysis outputs. If you like, you can edit this program. 2 Auto Mode: If the radio button is selected as Auto, then the software will automatically update this code based on any changes you make in the input dialog box. We recommend that you use this option to generate the R program so that all your input settings are used to generate analysis results. 3 Manual Mode: If you use the Manual option, then you will be allowed to edit the R program before the program is executed. Make sure that you specify a syntactically correct program; otherwise, the R program may report errors.

Verify

If you click on the Verify button, the software will perform some checks on the data you have entered. A sample screenshot of the data is shown in this figure.
 1 Verify Checks: The objective of this analysis as well as any checks that are performed are listed in this dialog box. For example, the software may check if you have correctly specified the input options and if you have specified the data correctly for analysis. 2 Check Status: The results of the analysis checks are listed here. If the checks are passed, then they are shown as a green-colored checkmark. If the verification checks fail, then they are shown as a red-colored cross. If the verification checks result in a warning, they are shown in the orange color exclamation mark and finally, any checks that are required to be performed by the user are shown as blue info icons.

Outputs

Click on Compute Outputs to generate the outputs from this analysis. A sample screenshot of the worksheet is shown below.
 1 Notes Section: The notes section contains a summary of the inputs used for creating the marginal plot. There are no specific analysis that is displayed in this section. 2 Graph Section: The graph section shows the marginal plot that was generated.

Notes

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

Examples

Following examples can be found in the Examples folder within the software.
• Create a Network Plot for the data shown in the examples folder (Network Plot 1.xlsm).

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.