python - How can I get a empty list when I use the enumerate before the loop? -


salary_data list in python.when used enumerate function in loop below,everything went well.

##salary_data = enumerate(salary_data) max_label = [i i,x in enumerate(salary_data) if x==max(salary_data)] print max_label

but when use enumerate function below,i got salary_data empty list,and valueerror: max() arg empty sequence.i don't know why.

salary_data = enumerate(salary_data) max_label = [i i,x in salary_data if x==max(salary_data)] print max_label

enumerate(salary_data) iterator because wrapped in enumerate. means exhausted (empty) when call max on (besides giving wrong maximum).

you should calculate max front (avoiding recalculation) , iterate on enumerated data:

max_ = max(salary_data)  # avoids repeated maximum calculation in loop salary_data_enumerated = enumerate(salary_data)  # other variable name, readability max_label = [i i, x in salary_data_enumerated if x==max_]

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