Using nested If statement in Python parser of ArcGIS Field Calculator?

Using nested If statement in Python parser of ArcGIS Field Calculator?

I'm trying to use field calculator to assign values to a new field I created. I wan't to assign the value from the first field unless that field is empty, if it is empty use field 2, if that is empty use field 3. Here is what I have thus far. I feel it is way off but not sure where to go from here.

New_Size: My new field

wmDeviceEq: First field to check for new field name

wmDevice_4: Second ""

wmDevice_5: Third ""

In the codeblock, you can only use parameters, not field names. You'll need to create parameters for each of your field names, like so:

def Reclass(f1, f2, f3): New_size = f1 # this doesn't actually do anything if f1 ==": return f2 elif f2 =="return f3 else: # is this cutoff? return f1 # New_size maybe?

and then

Reclass(!wmDeviceEq!, !wmDevice_4!, !wmDevice_5!)

What iff3(wmDevice_5) is empty? Not sure if your picture is showing a cuttoffelsestatement.

Are the values in the fields actually empty strings? Shapefiles store a single space" "and feature classes in a geodatabase typically use, which in Python would beNone.

If the fields are actually empty strings and only one field will ever have data, you don't need the code-block at all.

"".join((!wmDeviceEq!, !wmDevice_4!, !wmDevice_5!))

As an aside, a nestedifstatement would be something like this:

if result > 10: print("Greater than 10") if result < 100: print("and less than 100") else: print("It's big… ") else: print("Too small!")


I edited the code and came up with this

def Reclass( ph1, ph2, ph3 ): New_Size = ph1 if ph1 ==": return ph2 elif ph2 ==": return ph3 elif ph3 ==": print ("NULL")

and then

Reclass(!wmDeviceEq!, !wmDevice_4!, !wmDevice_5!)

When it runs my new field pulls values from only ph2… Also not sure about that final elif. it's meant to fill a space that has no value to pull, with a "Null".

I tried the "".join() function but it places spaces every time it moves to the next field, like so.

Won't work unless there is a way to remove those spaces before the values in the New_Size field.

Watch the video: QGIS Field Calculator Basics