Pandas make new column from string slice of another column

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You can call the str method and apply a slice, this will be much quicker than the other method as this is vectorised (thanks @unutbu):

df['New_Sample'] = df.Sample.str[:1]

You can also call a lambda function on the df but this will be slower on larger dataframes:

In [187]:

df['New_Sample'] = df.Sample.apply(lambda x: x[:1])
df
Out[187]:
  Sample  Value New_Sample
0    AAB     23          A
1    BAB     25          B

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