### GIS and decision support (4): a tool for aggregating fuzzy criteria with ArcMap

In this article we will discuss how to cross two fuzzy attributes, with
a command that we put at your disposal. The “Flexible Aggregation”
command allows the aggregation of two fuzzy criteria.
The interface offers three questions to the user to define the desired
aggregation formula. Then, the tool proceeds to the union or intersection of
the two criteria by producing a new data layer. This layer contains the data of
the two input layers plus one field with the result of the calculated
aggregation.
It is essential to create the fuzzy criteria before proceeding with their
aggregation.
In the case of non-numeric criteria, a manual transformation has to be executed
by the user to match numeric codes to the text attributes.

will discuss how to use the command, then how to install it.

Unfortunately, it is not enough to have an order to perform the job; we
must also understand what we do with it. This will refer to the next two
articles in this series, where we describe in detail the theoretical fundamentals
used by our orders.

Using the command

The button

displays the following interface

You must select which layers to use for the aggregation in the list of
available layers. The command works with shapefiles and geodatabases files
(gdb). It does not work with personal Geodatabases, enterprise geodatabases,
and Spatialite databases.

Below each layer, you must select the field, containing a fuzzy number,
to be used in the aggregation.
The layers in the list are automatically selected from the polygon layers.
Numeric fields are displayed, as long as their values ​​are between 0 and 1.
Those that start with fzy_ are automatically produced because they were created
by the Flexible Criteria command (see previous article: GIS and decision
support (3): a tool for creating fuzzy criteria with ArcMap
). However, you may have fuzzy
fields that do not result from the Flexible Criteria command and
that can be used for the aggregation.

Definition of the mathematical model of
aggregation.

The user must check the result of the three proposed aggregations. The
command tests the consistency of responses because some combinations are not
allowed.
For example, the result of the third question cannot be more unfavourable than
that of the first question. Indeed an average satisfaction of the first
criterion (third question) cannot lead to a more unfavourable result than a
total dissatisfaction (first question).
In fact, there are only 50 possible triplets as an outcome of these issues.

Definition of the type of aggregation operation.

The user can choose the aggregation operation:
1- The intersection of the two themes: the resulting theme will
only include the overlapping areas of the two themes to be aggregated. For
these areas the result of the calculated field is the product of the model
established by the answers to the three questions;
2- The union of the two themes: the resulting theme will include
the full extent of the two input themes. Zones with only one theme will have an
aggregation result of 0. Therefore, it can have two types of zones with the
field calculated at 0: those that correspond to a cross of two input values
​​giving as result total dissatisfaction, and when the dissatisfaction results
from a lack of data.

Showing the aggregation result

You have to check a box that allows you to
disable the automatic loading of the result in the ArcMap map window.
If it is not checked, the resulting layer is loaded with a pre-set rendering:

Five classes are calculated and displayed with a blue gradient:
• Entities resulting in 0
• Entities whose result is between 0 and 0.25
• Entities whose result is between 0.25 and 0.5
• Entities whose result is between 0.5 and 0.75
• Entities whose result is between 0.75 and 1

You do not have a button in this command allowing you to consult the
metadata of the fuzzy transformations. On the other hand, the resulting fuzzy
attribute is very explicit in the metadata of the layer. To view it, you must
use the Fuzzy Criteria command and click the attribute, then click the metadata
button.

The metadata is stored in a separate file (.fzy), managed by the
command.
The management of these files is automatic. For example, the elimination of
metadata corresponding to a flexible criterion if this criterion is manually
deleted from the table of the feature class.
However, if you move layers to different directories or geodatabases, you will
need to move the .fzy file manually.

Available languages

A drop-down list allows you to select the language to be used by both
commands.
The available languages are:
• French (default)
• English
• Spanish
• Vietnamese

Depending on the version of Windows used, it is sometimes necessary to
close and reopen the command so that all texts are in the chosen language.

And, for some unfathomable computing mystery, in some configurations of
Windows 8 the option es (Spanish) does not appear.

ArcGis versions

The commands can be used with ArcGis versions between 9.2 and 10.3. And
regarding Windows versions, controls work in Windows XP, Vista, W7 and W8.

Tools installation

The tool is provided as a .dll file.
To install it you have to go through the menu Customize -> Customize
mode
of ArcMap.
The customization window opens:

On the Commands tab, click the Add from File button. Check the fuzzy_agregationSA92_103ML.dll file that you have previously copied to a permanent directory on your local disk, with the Text.mdb file that contains the different language versions.
If you already have the Fuzzy Criteria tool installed, you do not have to copy the Text.mdb file, it is common to both commands.
Click OK . The following message should appear to indicate that the installation was successful.

Click OK. In the available Commands window you will be automatically positioned on the NASCA commands category where you will see two available tools: Flexible aggregation and Flexible Criteria (if you have already installed the Flexible Criteria command

In order to use them, click-drag on each of the commands and drop them into an open ArcMap toolbar.

flexible agregation user manual

Known Issues

In addition to the disappearance of Spanish from the drop-down list of available
languages, the most common problem is the use of the toolbox to make the
intersection or union of the input layers.

We chose to keep the same code, regardless of the ArcMap version. The
command runs for versions ranging from 9.2 to the latest, the 10.3.

In order to use the toolbox, it is necessary for the program to find the
corresponding ArcToolbox directory. As versions change, the path
has been changed several times, and sometimes the command cannot find it.

If this is your case, you will have an explicit message, telling and
inviting you to enter the correct path in a text file, created by the command
in the same directory where you placed the file. dll.

• Open the arcgishome.txt file with the notebook.
• Type the ArcGis installation
path, enclosed in quotation marks, for example:   C: \ Program Files (x86) \ ArcGIS \ Desktop10.3
“.   Do not finish the path with a ”   \   “.
• Restart the command, everything
must work without problems.

Go to the next article where we discuss the theoretical foundations of
the operation of the two commands.

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