How can I strip the whitespace from Pandas DataFrame headers?
Since version 0.16.1 you can just call .str.strip
on the columns:
df.columns = df.columns.str.strip()
Here is a small example:
In [5]:
df = pd.DataFrame(columns=['Year', 'Month ', 'Value'])
print(df.columns.tolist())
df.columns = df.columns.str.strip()
df.columns.tolist()
['Year', 'Month ', 'Value']
Out[5]:
['Year', 'Month', 'Value']
Timings
In[26]:
df = pd.DataFrame(columns=[' year', ' month ', ' day', ' asdas ', ' asdas', 'as ', ' sa', ' asdas '])
df
Out[26]:
Empty DataFrame
Columns: [ year, month , day, asdas , asdas, as , sa, asdas ]
%timeit df.rename(columns=lambda x: x.strip())
%timeit df.columns.str.strip()
1000 loops, best of 3: 293 µs per loop
10000 loops, best of 3: 143 µs per loop
So str.strip
is ~2X faster, I expect this to scale better for larger dfs
You can give functions to the rename
method. The str.strip()
method should do what you want:
In [5]: df
Out[5]:
Year Month Value
0 1 2 3
[1 rows x 3 columns]
In [6]: df.rename(columns=lambda x: x.strip())
Out[6]:
Year Month Value
0 1 2 3
[1 rows x 3 columns]
Note: that this returns a DataFrame
object and it's shown as output on screen, but the changes are not actually set on your columns. To make the changes, either use this in a method chain or re-assign the df
variabe:
df = df.rename(columns=lambda x: x.strip())