'How can I make pandas dataframe column headers all lowercase?

I want to make all column headers in my pandas data frame lower case

Example

If I have:

data =

  country country isocode  year     XRAT          tcgdp
0  Canada             CAN  2001  1.54876   924909.44207
1  Canada             CAN  2002  1.56932   957299.91586
2  Canada             CAN  2003  1.40105  1016902.00180
....

I would like to change XRAT to xrat by doing something like:

data.headers.lowercase()

So that I get:

  country country isocode  year     xrat          tcgdp
0  Canada             CAN  2001  1.54876   924909.44207
1  Canada             CAN  2002  1.56932   957299.91586
2  Canada             CAN  2003  1.40105  1016902.00180
3  Canada             CAN  2004  1.30102  1096000.35500
....

I will not know the names of each column header ahead of time.

Solution 1:^[1]

You could do it easily with str.lower for columns:

df.columns = df.columns.str.lower()

Example:

In [63]: df
Out[63]: 
  country country isocode  year     XRAT         tcgdp
0  Canada             CAN  2001  1.54876  9.249094e+05
1  Canada             CAN  2002  1.56932  9.572999e+05
2  Canada             CAN  2003  1.40105  1.016902e+06

In [64]: df.columns = df.columns.str.lower()

In [65]: df
Out[65]: 
  country country isocode  year     xrat         tcgdp
0  Canada             CAN  2001  1.54876  9.249094e+05
1  Canada             CAN  2002  1.56932  9.572999e+05
2  Canada             CAN  2003  1.40105  1.016902e+06

Solution 2:^[2]

If you want to do the rename using a chained method call, you can use

data.rename(columns=str.lower)

Solution 3:^[3]

df.columns = df.columns.str.lower()

is the easiest but will give an error if some headers are numeric

if you have numeric headers then use this:

df.columns = [str(x).lower() for x in df.columns]

Solution 4:^[4]

I noticed some of the other answers will fail if a column name is made of digits (e.g. "123"). Try these to handle such cases too.

Option 1: Use df.rename

def rename_col(old_name):
    return str(old_name).lower()

df.rename(rename_col)

Option 2 (from this comment):

df.columns.astype(str).str.lower()

Solution 5:^[5]

Another convention based on the official documentation:

frame.rename(mapper=lambda x:x.lower(), axis='columns', inplace=True)

Parameters: mapper: Dict-like or function transformations to apply to that axis’ values. Use either mapper and axis to specify the axis to target with mapper, or index and columns.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	Trenton McKinney
Solution 2	flying sheep
Solution 3	Chadee Fouad
Solution 4
Solution 5	nferreira78

'How can I make pandas dataframe column headers all lowercase?

Example

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Solution 5:[5]