I get the error TypeError: argument of type 'float' is not iterable

    import pandas as pd

keywords = {"metal", "energy", "team"}  # all your keywords

df = pd.read_csv("2008-data-8-8-2016.csv", sep=",")

output = pd.DataFrame(columns=df.columns)

for i in range(len(df.index)):
    if any(x in df['Position'][i] for x in keywords):
        output.loc[len(output)] = [df[j][i] for j in df.columns]

output.to_csv("ExtractedData_2008.csv", index=False)

This code is supposed to go throw file, and extract data based on the keywords. So it looks for the keywords in position column and take all the related data from other columns and copy them in new file. But I get this error (TypeError: argument of type 'float' is not iterable)

Any one can explain me what's the problem

Thanks in advance