How to correct UndefinedVariableError in python?-CodePudding

When I implement code for one paricular value of state name (see Last_ residence in code)

andhrapradesh.query('Duration_of_residence=="All durations of residence" & Last_residence_R_or_U=="Urban" & Last_residence=="Jammu & Kashmir"',inplace=True)
print(andhrapradesh['Total_migrants'].sum())

It gives desired sum of outflow value for that state from pandas csv. But when I tried to calculate for all possible names of state it's giving me error "UndefinedVariableError: name 'Jammu & Kashmir' is not defined"

states = ["Jammu & Kashmir","Punjab",'Himachal Pradesh']
for name in states:
    andhrapradesh.query(f'Duration_of_residence=="All durations of residence" & Last_residence_R_or_U=="Urban" & Last_residence=={name}',inplace=True)
    print(andhrapradesh['Total_migrants'].sum())

can you please figure out why it showing error and how can I do it for all values in list states.

CodePudding user response：

You need quotes around name like you had in your manual code:

df.query(f"... Last_residence == \"{name}\"")

so that it is seen as, e.g., "Punjab" as a string to check against but not bare Punjab which is sought specially, e.g., as a column name, hence the error.

(can use single quotes too...)

However, there's a better way: you can prefix a variable with @ symbol, so you don't even need the f-string:

df.query("... Last_residence == @name")