How to update a double field from a text field

[Laura]

I keep getting errors that it does not append when trying to do this. 

[DanPatterson]

You can't update the field type if there is data in the field.

Perhaps you can elaborate on what you are trying to do for alternate suggestions

[Laura]

i know that. the only work around was to create another field with the desired data type and fill it, however that is not working

[DanPatterson]

Or if you don't want to use a code block... (substitute !junk! for your field name of course)

float(!junk!) if !junk!.isnumeric() else None

[JohannesLindner]

Create a new Double field, then run Calculate Field with this Python expression (note the exclamation marks in line 2):

# NewField = 
convert(!OldField!)

# Code Block
def convert(x):
    try:
        return float(x)
    except:
        return None

[Laura]

These sound great. My specific issue is related to pipe diameter. So they have the " inch sign attached to the numbers, and that may be why it is not going into the double field?

[JohannesLindner · Accepted solution]

Yes. If it can't convert the string into a number, the conversion will fail. You need to strip out the character:

# NewField = 
convert(!OldField!)

# Code Block
def convert(x):
    try:
        x = x.replace('"', '')
        return float(x)
    except:
        return None

[Laura]

Awesome, that seemed to do the trick, thanks!