Specify a fields datatype while creating a new field in geodataframe with expression?

Question

I would like to know how to set the field type of ['denominator'] in a geodataframe manually in this expression to "String":

geo_df['denominator'] = df[["basalareap","basalareas","basalaread"]].sum(axis=1)

Where the fields "basalareap","basalareas","basalaread" contain floating point numbers

Automatic it assign the data-type "Double" (when check in QGIS), I tried to add the datatype in the first bracket, geo_df['denominator', type= "String"] but this throws an error.

I'm using Windows 10, Python 3.7

Answer 1

Not really GIS related, but you can use the astype method:

geo_df['denominator'] = df[["basalareap","basalareas","basalaread"]].sum(axis=1).astype(str)