pandas: truncate string columns of pandas dataframe

truncate string columns.py

# groupby over all columns that are strings and truncate them; useful in case we plan to output to excel
import pandas as pd
import numpy as np
maxChars = 2 # maximum number of characters to retain 
df = pd.DataFrame({'key1': ['a','a','b','b','a'],
                   'key2': ['one', 'two', 'one', 'two', 'three'],
                   'data1': np.random.randn(5),
                   'data2': np.random.random(5)})
print(df)
# iterate over columns that are type object
for col in df.select_dtypes(include=[object]):
    if __name__ == '__main__':
        df[col] = df[col].str.slice(0, maxChars)
print(df)