topic Re: Field calculator to update a field using another field in attribute table in Python Questions

Field calculator to update a field using another field in attribute table

DuminduJayasekera — Mon, 09 Oct 2017 16:41:18 GMT

Hi,

I have the following attribute table. I need to update the fields using the field calculator (SEC, TOWN, RANG) by using the "mtrs" and "label" columns(fields) in the attribute table.

SEC: (letter S + label) TOWN: (string from mtrs) RANGE (string from mtrs) S_R_T (join the SEC+TOWN+RANG)

S24 T1N R14W S24-T1N-R14W

S4 T1N R14W S24-T1N-R14W

S34 T2S R8W S34-T2S-R8W

Can somebody help me to achieve this using the "Field Calculator" and Python parser functions?

Thanks a lot in advance.

Re: Field calculator to update a field using another field in attribute table

DanPatterson_Retired — Mon, 09 Oct 2017 17:43:42 GMT

"{}-{}-{}".format(!A!, !B!, !C!)‍

just replace A, B and C with your field names but keep the ! ! marks around them.

Obviously , this has to go into a text field and you have to specify python as the o\parserf

Re: Field calculator to update a field using another field in attribute table

DanPatterson_Retired — Sat, 11 Dec 2021 17:13:41 GMT

table is hard to read, but I suspect that you are also having trouble with the other bits, like getting the SEC field which would be

sectn = '024'

"S{}".format(int(sectn))  # in field calculator  !sectn! with python parser‍‍‍

or are those ok... it isn't clear whether you need the whole process completed, just some bits, or all the work? And how much python do you know?

Re: Field calculator to update a field using another field in attribute table

DuminduJayasekera — Thu, 12 Oct 2017 21:12:16 GMT

Thanks Dan. Yes I figured and it worked. I am a beginner to Python.

Re: Field calculator to update a field using another field in attribute table

DanPatterson_Retired — Fri, 20 Oct 2017 20:16:24 GMT

Did you find an alternate solution or do you want to close the thread?

Re: Field calculator to update a field using another field in attribute table

DuminduJayasekera — Wed, 25 Oct 2017 21:16:55 GMT

Apologies for the late reply. Your answers were very helpful. Is there a way I can extract RANGE using the "mtrs" column?

Re: Field calculator to update a field using another field in attribute table

DanPatterson_Retired — Wed, 25 Oct 2017 21:31:38 GMT

Yes... what have you tried and what should it look like?

This type of functionality is simply python string slicing

other functions string functions

Re: Field calculator to update a field using another field in attribute table

DuminduJayasekera — Wed, 25 Oct 2017 22:00:34 GMT

I used

"R{}".format(int(!mtrs![11:13])) but I am not able to get the East "E" or "W" letter attached like R1E or R18W.

Re: Field calculator to update a field using another field in attribute table

DanPatterson_Retired — Sat, 11 Dec 2021 17:13:44 GMT

ahhh... slicing again

x = 'abcdefghi__13E'  # ---- since you didn't include an example ----

"R{}{}".format(int(x[11:13]), x[13])  # x = !mtrs!

'R13E'‍‍‍‍‍

Re: Field calculator to update a field using another field in attribute table

DuminduJayasekera — Thu, 26 Oct 2017 13:55:24 GMT

You are genius. I got the trick now. Thanks a bunch.

Re: Field calculator to update a field using another field in attribute table

DanPatterson_Retired — Thu, 26 Oct 2017 14:05:35 GMT

Dumindu could you select the answer that answered the question to close the thread.

Re: Field calculator to update a field using another field in attribute table

DuminduJayasekera — Thu, 26 Oct 2017 14:15:24 GMT

I did. Thanks.