Graphs Tab

Graphs Tab
This tab allows generation of graph format files from hexmaps.

Add hexmap

These buttons allow you to browse and add (and remove) hexmaps representing habitat values that will be used to derive distance, conductance, or capacity values in the output graph.
In the case of time series analysis, several hexmaps may be listed in order of their time series step.

List of hexmaps

Except in time series analysis, only one hexmap will be listed.

Add cost hexmap [optional]

A hexmap representing cost, which is only supported when using the min-cost-max-flow method. Note that cost here is used in a different context than the attribute considered in 'least-cost-path' analysis (which is here termed 'distance').

List of cost hexmaps [optional]

Cost hexmap(s) are listed here if the min-cost-max-flow method is being used. In time series analysis, each step for which a habitat hexmap is specified (above) must also have a cost hexmap listed.

Browse for location to put graph format file


Name of graph format file


Type of graph format file to be output

The types of graph format files available are:
1) LGF Directed
2) LGF Undirected
3) Edge list - Distance
4) Edge list - Conductance
5) Edge list - Directed
See 'Output files' documentation page above for description.

No Data Value check

Typically, if the input .asc file was generated in ArcGIS, it will have represented areas without data as the value -9999. However, if a different NODATA value was used, it can be specified here. In almost all cases, users will want to check this option so as to exclude areas without data from being considered as nodes in graph file generation.

Convert Scores to Integer Values check

The network flow methods (e.g., min-cost-max-flow) use algorithms that perform better with integer than with floating-point values. Therefore if a network flow method is selected, this box will be checked by default. Conversely, this step is not allowed for the betweenness and current flow methods. Floating-point values may be converted to integers and yet retain adequate precision by multiplying by a power of 10 to retain digits that occur after the decimal point in the floating-point input. For example, if 2 digits of precision are specified, then the value 12.546 would be converted to 1255 (values are rounded to the next highest integer). Do not specify more digits than necessary as this will slow subsequent calculation of connectivity metrics, and may in exterme cases prevent the function from completing.

Neighborhood Radius

Used in time-series LGF creation only. Determines radius (in hexagons) up to which hexagons will be considered neighbors connected by between-year arcs.

Run button

Create the graph format file.

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