How to write labels with varying significant figures/decimal places?

Question

I have results that range from ex. 113,009 down to 0.00495 - Can someone recommend a way to write/construct a label expression for the following in ArcMap:

• If less than 1, use 2 decimal places (or three if absolutely necessary to show the first non-zero value) • From 1 to 10, use 1 decimal place • If 10 or greater, use no decimal places

Or a way to quickly generate a new text column/field which adheres to the above?

Answer 1

Put the code below as the label expression for your feature in ArcMap. Set the parser to Python and check the Advanced box. Change [yourField] to the field containing the values you want to label.

def FindLabel([yourField]):
    if [yourField] is not None:
        value = float([yourField])
        if value < 1:
            return round(value, 3)
        elif 1 <= value < 10:
            return round(value, 1)
        else:
            return round(value, 0)
    else:
        return None

I put the values that are less than one to three decimal places, but change it to two if you want.