substring of an entire column in pandas dataframe

Question

I have a pandas dataframe  df   In this dataframe I have multiple columns  one of which I have to substring  Lets say the column name is  col   I can run a  for  loop like below and substring the column   for i in range 0 len df      df iloc i  col   df iloc i  col  9    But I wanted to know  if there is an option where I don t have to use a  for  loop  and do it directly using an attribute I have huge amount of data  and if I do this  the data will take a very long time process

User · Accepted Answer

Use the str accessor with square brackets   df  col     df  col   str  9    Or str slice   df  col     df  col   str slice 0  9

User · Answer

case the column isn t string  use astype to convert  df  col     df  col   astype str  str  9

User · Answer

I needed to convert a single column of strings of form nn n  to float    I needed to remove the   from the element in each row   The attend data frame has two columns   attend iloc   1 2  attend iloc   1 2  applymap lambda x  float x  -1      Its an extenstion to the original answer    In my case it takes a dataframe  and applies a function to each value in a specific column   The function removes the last character and converts the remaining string to float

[python] substring of an entire column in pandas dataframe

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