using a for loop to rename columns of a list of data frames

user_17406588 0
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I have a list of dataframes I have saved in a variable x.

x=[df_1963,df_1974,df_1985,df_1996,df_2007,df_2018]

I wish to change all the headers to lowercase but nothing happens after the running the code below.

for df in x:
    for column in df.columns:
        df = df.withColumnRenamed(column, '_'.join(column.split()).lower())
pandas dataframe python
3 Answers

You can do it in a list and dict comprehension way. Try with:

renamed_x = [a.rename(columns={y:y.lower() for y in a}) for a in x]

The inner dict comprehension generates a dictionary with the columns' original values and its lowercase, so that is how each dataframe's columns will be renamed in lowercase; while the outer list comprehension iterates over all the dfs.

user_118970070

Can use df.columns to access each df's columns instead of looping through:

for df in x:
    df.columns = df.columns.str.lower()
user_167951750

You could use Series.map for columns as well:

for df in x:
   df.columns = df.columns.map(str.lower)
user_14103030
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