[GIS] How to compare two files with FME

fme

I have two csv files which each have a field containing the same feature type but with different field names. I need to compare the values of these fields in the two files to find out where there are differences? How do I do this in FME.

Best Answer

Just use the Change Detector. There's nothing more to it. You can check that the geometry is the same, or just check attributes.

See the description from FME help:

ChangeDetector

Detects changes between two sets of input features.

This transformer is often used with multiple readers, to identify changed features in the two files. It can identify all features that two input files have in common, and those which are in one file and not the other, such as the additions and the deletions.

As usual with FME, they have already implemented something, so doing it yourself with a CRC Calculator, or feature merging is unnecessary.

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To join the tables use featureMerger using the ID as key match. To create ID's use the counter.

hope it helps Regards Jorge Vidinha

FME – How to Read Files One by One

I would second @Mapperz comment about upgrading - FME 2012 SP2 contains some significant improvements. If you have a current active maintenance contract then you can download the latest version direct from Safe Software.

As is always the case there are several different ways you can achieve the right result using FME. Here are two approaches you could consider:

Approach 1: MS-DOS Batch Script

When you run a workspace from within FME Workbench what you are actually doing is executing the command-line fme executable. Armed with this knowledge it is straight forward to execute a workspace from the command-line, in fact FME Workbench makes it even easier for you as the top of the log in the log viewer panel will display the command-line to use if you want to execute the workspace from a DOS prompt.

Using that information you can create a batch file to scan a directory of files and then send them one-by-one to FME for processing. For example:

SET FME="C:\Program Files\FME\fme.exe"
SET SOURCE_DATA_DIR="D:\Temp"
SET FME_WORKBENCH="YourWorkspace.fmw"
REM Set any other options here

FOR %%A IN (%SOURCE_DATA_DIR%\*.xml) DO (%FME% %FME_WORKBENCH% --SOURCE_FILE %%A)

Obviously you will need to adpat this to your needs but use the output from running your workspace in FME Workbench as a guide.

Approach 2: Controller Workspace

An alternative approach is to use a controller workspace to execute another workspace repeatedly based on some input. In this case the input will be the path to an XML file. This is straight forward to setup, all you need is a Files and Directories reader and a WorkspaceRunner transformer. An example of how this would look in FME Workbench below:

Example of a controller workspace

An extremely useful resource for all things FME is the FMEpedia site. Lots of examples and help doing all maaner of things with FME.

Best Answer

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