topic Re: Calculate Field, Helpers, Reclassify, If/elif in ArcGIS Pro Questions

Calculate Field, Helpers, Reclassify, If/elif

GJB — Fri, 08 Oct 2021 19:36:05 GMT

Hello, in PRO I am trying to use Python / Code Block to use existing field !prim_lith! (text field, with geologic material descriptions, eg, clay, sand) to populate a new field !prim_lith_reclass! (short integer field) whose value 1, 2, 3,...9 depends on the geologic material in !prim_lith!. The Expression is valid and runs but the return values are all equal to 1 (from line 3 in the code block), see lower right of attached jpg. I've tried varied syntax etc. but nothing seems to work. Should text be in double quotes "text", or double apostrophe 'text' ? What is the difference between != and == ? Do I have to explicitly enter an Else?

Any insights would be greatly appreciated. Thank you!

Re: Calculate Field, Helpers, Reclassify, If/elif

JayantaPoddar — Fri, 08 Oct 2021 19:48:04 GMT

!= means "not equal to"

== means "equal to"

I think you have put != instead of == ?

Please replace != with ==

Re: Calculate Field, Helpers, Reclassify, If/elif

GJB — Fri, 08 Oct 2021 19:54:05 GMT

Thank you, that makes sense. I replaced as suggest and the expression is still valid but now get a run error 000539 (attached).

Re: Calculate Field, Helpers, Reclassify, If/elif

DavidPike — Fri, 08 Oct 2021 20:17:27 GMT

please format your code, you're also not showing the entire code block. It makes it very tedious to try and help you Code formatting ... the Community Version - Esri Community

Can't even see line 42 of your code.

I would add an else at the end to take into account misspellings etc. set it as something like 999,-999 or whatever.

else: a = 999 return a

Re: Calculate Field, Helpers, Reclassify, If/elif

JayantaPoddar — Fri, 08 Oct 2021 20:48:31 GMT

Putting the whole codeblock here would help.

Ensure that you have returned variable a with appropriate indentation.

Could you check with a code-block similar to the following

def Reclass(fld): if fld=='soil or fill': return 1 elif fld=='alluvium': return 2 else: return 9

Re: Calculate Field, Helpers, Reclassify, If/elif

GJB — Fri, 08 Oct 2021 21:11:59 GMT

Okay I apologize for that. I couldn't fit the vertical extent of the code block into Snip so I've attached the top and bottom halves.

In any case, I incorporated your ideas and the code now works! Thank you for the insights!

Re: Calculate Field, Helpers, Reclassify, If/elif

JayantaPoddar — Fri, 08 Oct 2021 22:04:55 GMT

Glad we could help!

For your future queries, here is How to insert code in your post - Esri Community

Re: Calculate Field, Helpers, Reclassify, If/elif

SGuiryVR — Mon, 08 Nov 2021 21:34:56 GMT

In the code that was submitted is an elif statement needed for all values even if they are to be classified into the same category? I am seeing at least 7 values where a=4 but am wondering if all of these classes that will be reclassified could be included in the same piece of code? I am trying to do something similar so seeing if there is a more concise way of writing the code block

Re: Calculate Field, Helpers, Reclassify, If/elif

LauraTateosian_augori — Tue, 12 Sep 2023 21:51:03 GMT

A bit late, but maybe this will help others. The original code needed first to have != changed to == (as mentioned above). But once you do that, you're right, you could combine all of the statements that wanted to set the value to 4 by using a list and then checking for membership in the list. For example, you could do something like this:

four_type_soils = ["Till", "Paleasol", "Clay"] if fld == "Soil or Fill": a = 1 elif fld == "Alluvium": a = 2 elif fld == "Loess": a = 3 elif fld in four_type_soils: a = 4 else: a = 9