How can I remove extra whitespace from strings when parsing a csv file in Pandas?

Well, the whitespace is in your data, so you can’t read in the data without reading in the whitespace. However, after you’ve read it in, you could strip out the whitespace by doing, e.g., df["Make"] = df["Make"].map(str.strip) (where df is your dataframe).

I don’t have enough reputation to leave a comment, but the answer above suggesting using the map function along with strip won’t work if you have NaN values, since strip only works on chars and NaN are floats.

There is a built-in pandas function to do this, which I used:
pd.core.strings.str_strip(df['Description'])
where df is your dataframe. In my case I used it on a dataframe with ~1.2 million rows and it was very fast.

Adding parameter skipinitialspace=True to read_table worked for me.

So try:

pd.read_table("data.csv", 
              sep=r',', 
              names=["Year", "Make", "Model", "Description"], 
              skipinitialspace=True)

Same thing works in pd.read_csv().

Here’s a function to iterate through each column and apply pd.core.strings.str_strip:

def df_strip(df):
  df = df.copy()
  for c in df.columns:
    if df[c].dtype == np.object:
      df[c] = pd.core.strings.str_strip(df[c])
    df = df.rename(columns={c:c.strip()})
  return df

The str.strip() function works really well on Series. Thus, I convert the dataframe column that contains the whitespaces into a Series, strip the whitespace using the str.strip() function and then replace the converted column back into the dataframe. Below is the example code.

import pandas as pd
data = pd.DataFrame({'values': ['   ABC   ', '   DEF', '  GHI  ']})
new = pd.Series([])
new = data['values'].str.strip()
data['values'] = new

I don’t believe Pandas supported this at the time this question was posted but the the most straight forward way to do this is by using regex in the sep parameter of read_csv. So something like the following should work for this issue.

table = pd.read_table("data.csv", sep=' *, *')

read_table is Deprecated, Here is the message as it appears in the documentation.

Deprecated since version 0.24.0.

Use pandas.read_csv() instead, passing sep=’t’ if necessary.

So using read_csv you can pass in a regex for the sep argument, where you can specify the separator as

sep="s*,s*"

any number of spaces, followed by a separator, followed by any number of space again, this will make sure all the leading and trailing spaces are also chosen as a delimiter chunk which in-turn removes the white-spaces on either side of your data.

regex details as follows:

s -> white-space
* -> any number (zero or many)
, -> no meaning, direct character match

So, the regular expression s*,s* stands for white-space[any number] match a comma and white-space[any number].

if your delimiter is anything else other than a comma then replace the , in the above expression with your delimiter. Eg: s*;s* if ; is your delimiter.

For me the best way was

def read_csv_regex(data, date_columns=[]):
    df = pd.read_csv(data, quotechar='"', parse_dates=date_columns)

    # remove front and ending blank spaces
    df = df.replace({"^s*|s*$":""}, regex=True) 

    # if there remained only empty string "", change to Nan
    df = df.replace({"":np.nan}) 
    return df

You don’t need to write converter function and set it to every column, it works for head and tail spaces and has now problem with quotas unlike regexp sep.

See https://towardsdatascience.com/dealing-with-extra-white-spaces-while-reading-csv-in-pandas-67b0c2b71e6a#9281