KeyError when creating new column

1
votes

I am trying to open the two most recent .csv files from a folder stored on my hard drive. Upon reading in each df, I want to create a column containing the name of the file that was read in, but I keep getting KeyError: 'file_name'.

Any help would be greatly appreciated.

Thanks!

files = glob.glob(r"path\*.csv")
sorted_files = sorted(files, key=os.path.getmtime, reverse = True) #sorting files from newest to oldest

buyandsell_df = []
for index, file in enumerate(sorted_files):
    if index == 2: #only open two most recent files from sorted_files list
        break
    else:
        print("READING IN " + file)
        df = pd.read_csv(file, usecols=['language','title','contract_number','publishing_status','award_date','publication_date','amendment_date','contract_value'], low_memory = False)
        df['file_name'] = file
        df = df.loc[df['language'] == 'English'] # filter out french duplicates
        buyandsell_df.append(df)
python
Have you looked at the structure of the df object after the df = pd.read_csv(...) line? - FCo
The error is that 'file_name' is not in df - Benjamin W.
What makes you think df['file_name'] exists? df=pd.read_csv... is producing a data frame not a file. - Adrian Klaver
Is this the actual code? Which line of code results in KeyError? You should always include full diagnostic information in your post. - jarmod
@AdrianKlaver if you are assigning a new key value python dict will create a new one this is not the source of the error. he is probably reading from it before creating it somewhere else in the code. - Farid Fakhry