topic Re: Use arcpy to check if .lyr file uses relative path names in Python Questions

Use arcpy to check if .lyr file uses relative path names

AnthonyCheesman1 — Wed, 01 Feb 2017 01:24:28 GMT

I have a library of many hundred .lyr files that are distributed to my user base along with a data package.

Users will save the data and layer files on various drive letters and directory locations. This works fine as the layer files are generally saved with relative file paths (creating using tool "Save To Layer File" and selecting the 'Store Relative Path' option.

I would now like to develop an audit process for the layer file library, and to do so I will walk through the directory structure and iterate through all of the .lyr files. For each file I will check if the data source is current (which I've worked out how to do) and then check that the .lyr file path is relative (which I haven't worked out how to do).

Is there an arcpy method that I can check this component of the .lyr file properties? I would imagine it sits somewhere with the layer methods, but I can't see any reference to this property in the documentation.

Thanks

Re: Use arcpy to check if .lyr file uses relative path names

DanPatterson_Retired — Wed, 01 Feb 2017 01:34:46 GMT

There are methods inside the layer class

layer class

Re: Use arcpy to check if .lyr file uses relative path names

AnthonyCheesman1 — Wed, 01 Feb 2017 03:37:46 GMT

Thanks Dan.I have combed through the methods and haven't come up with anything that I think will help me, but it is entirely possible that I've missed or misinterpreted something.

My working solution for the moment is to compare the layer source (eg J: drive) with the layer location (eg C:) and if there is a difference, flag it for further investigation. I was hoping for a more definitive test if one exists though.

Re: Use arcpy to check if .lyr file uses relative path names

DanPatterson_Retired — Wed, 01 Feb 2017 04:03:54 GMT

The paths can be changed... I doubt they are kept as relative since if you add a layer to a map document and separate it from its data, the link is broken... to fix, arcpy has the functionality

Changing a layer's data source is a common requirement. There are two methods on the Layer object that help with this. The findAndReplaceWorkspacePath method is intended for replacing part or all of a layer's workspace path. The replaceDataSource method allows you to change a layer's workspace and source dataset. For a more detailed discussion, parameter information, scenarios, and code samples, please refer to the Updating and fixing data sources with arcpy.mapping help topic.

Re: Use arcpy to check if .lyr file uses relative path names

DanPatterson_Retired — Wed, 01 Feb 2017 04:10:24 GMT

and an addendum, suggesting that it is way the project was saved that affects whether absolute or relative paths are saved... you will have to experiment with a project with and with out relative paths linked

Once you've saved the layer file, you can't change the data source options from absolute to relative or vice versa. The layer will always maintain the data source option that was set for the map document at the time you saved the layer.

From Referencing data in the map—Help | ArcGIS Desktop

at the bottom

Re: Use arcpy to check if .lyr file uses relative path names

GrantHerbert — Thu, 26 Oct 2017 00:13:23 GMT

The only way I have found to identify if a layer file is relative - is to open it in Notepad (not Notepad++. Sublime or anything else, just Notepad) and search for ". . \" - spaces and all.

Re: Use arcpy to check if .lyr file uses relative path names

XanderBakker — Sat, 11 Dec 2021 17:51:55 GMT

The only thing I can come up with is to copy the layerfile to another location and see if the datasource is still pointing to the same location (absolute) or not (relative):

def main():
    import arcpy
    import os
    from shutil import copyfile
    tmp_folder = r'C:\GeoNet\RelativePath\tmp'

    lyrs = [r'C:\GeoNet\RelativePath\Layerfile_relative_path.lyr',
            r'C:\GeoNet\RelativePath\Layerfile_absolute_path.lyr']

    for lyr_file in lyrs:
        print "\n", lyr_file
        lyr = arcpy.mapping.Layer(lyr_file)
        datasource_before = lyr.dataSource
        print "before:", datasource_before
        lyr_file_dest = os.path.join(tmp_folder, os.path.split(lyr_file)[1])
        print lyr_file_dest
        copyfile(lyr_file, lyr_file_dest)
        lyr_tmp = arcpy.mapping.Layer(lyr_file_dest)
        datasource_after = lyr_tmp.dataSource
        print "after :", datasource_after
        if datasource_before == datasource_after:
            print " - Datasource is Absolute path"
        else:
            print " - Datasource is Relative path"


if __name__ == '__main__':
    main()‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

This yields:

C:\GeoNet\RelativePath\Layerfile_relative_path.lyr
before: C:\Fabiola\ManglaresInvemar\gdb\ManglarCentroPob.gdb\Manglares
C:\GeoNet\RelativePath\tmp\Layerfile_relative_path.lyr
after : C:\GeoNet\Fabiola\ManglaresInvemar\gdb\ManglarCentroPob.gdb\Manglares
 - Datasource is Relative path

C:\GeoNet\RelativePath\Layerfile_absolute_path.lyr
before: C:\Fabiola\ManglaresInvemar\gdb\ManglarCentroPob.gdb\Manglares
C:\GeoNet\RelativePath\tmp\Layerfile_absolute_path.lyr
after : C:\Fabiola\ManglaresInvemar\gdb\ManglarCentroPob.gdb\Manglares
 - Datasource is Absolute path‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Use arcpy to check if .lyr file uses relative path names

curtvprice — Sat, 11 Dec 2021 17:51:58 GMT

The only way I have found to identify if a layer file is relative - is to open it in Notepad (not Notepad++. Sublime or anything else, just Notepad) and search for ". . \" - spaces and all.

If this works consistently, you could easily read the layer file with Python and look for this string. It's a kluge, but why not if it works?

def lyr_relpath(lyrfile):
    with open(lyrfile, 'rb') as f:
        data = f.read()
        gotRelative = (data.find(". . \\") > -1 or 
                       data.find(". . /") > -1‍‍‍‍‍‍‍‍)
    return gotRelative‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Use arcpy to check if .lyr file uses relative path names

XanderBakker — Sun, 29 Oct 2017 17:56:31 GMT

Hi curtvprice ,

Does this code work for you? I just applied it to the two layerfiles I have and both returned false.

Re: Use arcpy to check if .lyr file uses relative path names

curtvprice — Mon, 30 Oct 2017 02:29:05 GMT

No it doesn't. I looked at my two test files in notepad (one save as layer file with mxd relative paths on, one off) and can't find the magic cookie that Grant mentioned. So I'm kind of confused.

Re: Use arcpy to check if .lyr file uses relative path names

GrantHerbert — Fri, 03 Nov 2017 19:32:17 GMT

Do you see a drive path when you open them in Notepad?

Re: Use arcpy to check if .lyr file uses relative path names

XanderBakker — Fri, 03 Nov 2017 19:44:58 GMT

I don't...

Re: Use arcpy to check if .lyr file uses relative path names

curtvprice — Fri, 03 Nov 2017 21:47:38 GMT

I don't either, Xander's method is probably best then.

Re: Use arcpy to check if .lyr file uses relative path names

GrantHerbert — Fri, 03 Nov 2017 23:48:43 GMT

This is what I see when I open the layer file in Notepad, for a layer file created with arcpy.SaveToLayerFile_management with is_relative_path set to "RELATIVE".

However I have just realized that the ". . \" does not always exist - it depends on where your data resides. However, a check for ": \" may identify an absolute path. This will probably require searching for the encoded values, which will look like b'\x00F' for example. I have no idea what the correct code for ':' would be though.