topic Re: Example using search cursor to copy data from cells in attribute table A to attribute table B in Python Questions

Example using search cursor to copy data from cells in attribute table A to attribute table B

MPach — Tue, 05 Sep 2023 20:29:07 GMT

Does anyone have an example of how to copy data from a cell in attribute A to a cell in Attribute B?

Ideally, here's an example of what I would like to do.

1) Select the two features in the map I'd copy data from

2) From Feature_A Copy cell from column1, column2, and column3

3) Paste data from step 2 into Feature_B cells for column3, column4, and column5

I didn't see an example like this, which seems like a pretty basic use of the search cursor.

Thanks in advance!

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

AlfredBaldenweck — Tue, 05 Sep 2023 19:20:45 GMT

You just have to nest it with either an update cursor or insert cursor, depending on if the target row already exists.

Rough, untested code:

#search through rows with arcpy.da.SearchCursor(fc1, [fields]) as cursor: for row in cursor: #do something to match the rows, probably a where clause along these lines with arcpy.da.UpdateCursor(fc2, [fields] where_clause = 'field = row[2]') as c2rsor: for r2w in c2rsor: r2w = row c2rsor.updateRow(r2w)

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

JohannesLindner — Tue, 05 Sep 2023 19:28:49 GMT

You can accomplish that with the arcpy.da.*Cursor classes:

copy_layer = "Layer A" copy_fields = ["columns1", "column2", "column3"] paste_layer = "Layer B" paste_fields = ["column3", "column4", "column5"] # read the first copy feature data = [row for row in arcpy.da.SearchCursor(copy_layer, copy_fields)][0] # paste the copy feature's data into each paste feature with arcpy.da.UpdateCursor(paste_layer, paste_fields) as cursor: for row in cursor: cursor.updateRow(data)

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

DavidPike — Tue, 05 Sep 2023 19:31:24 GMT

Prefer this over instantiating a cursor for each row.

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

BlakeTerhune — Tue, 05 Sep 2023 19:41:13 GMT

Agreed, this is my preferred method as well. It's also the methodology @RichardFairhurst uses for Turbo Charging Data Manipulation with Python Curso... - Esri Community

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

MPach — Tue, 05 Sep 2023 20:18:11 GMT

Thank you Johannes. Cheers!

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

MPach — Tue, 05 Sep 2023 20:19:50 GMT

Thanks Blake, I saved that link to my favorites folder. Much appreciated!

Re: Example using search cursor to copy data from cells in attribute table A to attribute table B

AlfredBaldenweck — Tue, 05 Sep 2023 20:42:41 GMT

Oh, I've never seen that done that way. That is slick.

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

MPach — Fri, 08 Sep 2023 14:15:55 GMT

Johannes or @DavidPike is there anyway to get this script to work based on the records selected in both the copy layer and the paste layer. I only want to paste the information selected on a one to one basis instead of a one to many or one to all. Right now it appears it's using the selected record in the copy layer, but it is pasting that data to all the records in the paste layer. I thought that if I selected the records in each table before running the script that it would respect that selection, but it doesn't look like it's functioning that way.

Thank you so much for you help,

Mark

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

JohannesLindner — Mon, 11 Sep 2023 09:44:13 GMT

You're right, it takes only the first feature in the copy layer and pastes its attributes into all features of the paste layer.

If you want to do a one-to-one copy/paste based on selection, you can do it like this:

# read all copy features data = [row for row in arcpy.da.SearchCursor(copy_layer, copy_fields)] # paste their attributes into the paste features with arcpy.da.UpdateCursor(paste_layer, paste_fields) as cursor: for i, row in enumerate(cursor): try: cursor.updateRow(data[i]) except IndexError: print("You selected too few features in the copy layer, only {} features in the paste layer were processed!".format(i)) break if i+1 < len(data): print("You selected too many features in the copy layer, {} features were not copied!".format(len(data)-i-1))

Note that both layers will be processed in order of OBJECTID. So the attributes of the copy feature with the lowest OID will be pasted to the paste feature with the lowest OID.

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

MPach — Mon, 11 Sep 2023 12:57:21 GMT

Thank you Johannes. Very much appreciated! That saves me a bunch of time.

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

MPach — Mon, 11 Sep 2023 15:34:18 GMT

I see how that is different, but I'm not sure if that will do what I'm looking for. I need to be able to select one field in the copy_layer and paste the values of those copy_fields to just a single asset in the paste_layer that I would be selected before the script is run.

Example:

Selected field from Copy_Layer

Paste that info in the copy_layer that is selected

Is there a way to do that? I'm asking because it's possible that the the OBJECTIDs for each of these are not correlated correctly where the lowest OID from the copy_layer will match with the correct feature from the paste_layer. i.e. spatially, feature 001 from the copy layer may correlate with feature 099 from the paste layer , which would mean there a different feature with a lower OBJECTID like 040 from the paste_layer would match with with 001 from the copy layer.

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

BlakeTerhune — Mon, 11 Sep 2023 15:59:56 GMT

You need a key field to relate tables like this. Agreed that ObjectID is not a good key field. Do you have a field that relates a particular record from the copy layer to the paste layer?

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

MPach — Mon, 11 Sep 2023 16:04:06 GMT

Unfortunately, I don't in this case, which is why I need to use a manual selection from the map or from the attribute tables. If I had a key field to relate I wouldn't need to this 😞

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

MPach — Mon, 11 Sep 2023 16:05:25 GMT

It seems a little mind blowing that this can't be done in Python at this point.

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

BlakeTerhune — Mon, 11 Sep 2023 16:16:15 GMT

If you need to run this as a script instead of a toolbox, you can access the selected records of a layer using the getSelectionSet() method on the layer object.

Layer—ArcGIS Pro | Documentation

You'll use some other arcpy.mp stuff to get to the layer you want in the map you want.

EDIT:

Sorry, I forgot you're using ArcMap. You can still get the selection set of a layer with arcpy.mapping

Layer—ArcMap | Documentation (arcgis.com)

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

JohannesLindner — Mon, 11 Sep 2023 16:16:50 GMT

But doesn't my first script solve this case? Just select both features and run the script. The script will take the first feature of the copy layer (which has only one feature selected, so it doesn't matter) and copies it to all selected features in the paste layer (which also has only one feature selected), so you get a 1-to-1 copy.

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

MPach — Mon, 11 Sep 2023 16:27:38 GMT

Hmmmm, I don't think it does though unless I'm not understanding something. Maybe I'm not stating what I am trying to accomplish clearly.

The first script copies the data from layer A and pastes it to all the records in layer B. I was hoping to find a way to copy the record from layer A and only paste that record (no other records) to a record that I have preselected in the attribute table in layer B.

Does that make sense?

Thanks,

Mark

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

MPach — Mon, 11 Sep 2023 16:49:28 GMT

Maybe this will help. If I used the first script I couldn't use it a second time for a different record because the doing so would cause the data from the first use to be overwritten for the next use. Does that help?

I intend to use the script for multiple features in the copy_layer and the paste_layer

Mark

Re: Example using search cursor to copy data from a cells in attribute table A to attribute table B

BlakeTerhune — Mon, 11 Sep 2023 17:09:15 GMT

Without a key field, you cannot do multiple features. You would have to manually select exactly one in each table to copy the values. Otherwise, there's no way for the code to match to the correct record.