Daidalos April 14, 2020

Example of how to subtract by a number the elements of a datafame column with pandas in python:

Let's create a data frame with pandas called df:

`>>> import pandas as pd`

`>>> import numpy as np`

`>>> data = np.arange(1,13)`

`>>> data = data.reshape(3,4)`

`>>> df = pd.DataFrame(data=data,columns=['a','b','c','d'])`

`>>> df`

`a b c d`

`0 1 2 3 4`

`1 5 6 7 8`

`2 9 10 11 12`

Let's select the column b for example:

`>>> df['b']`

`0 2`

`1 6`

`2 10`

to subtract by 10 the elements of the column b, a solution is to do

`>>> df['b'] = df['b'] - 10`

`>>> df`

`a b c d`

`0 1 -8 3 4`

`1 5 -4 7 8`

`2 9 0 11 12`

Links | Site |
---|---|

Apply a function to a single column in Dataframe | thispointer.com |

pandas.DataFrame.apply | pandas doc |

License

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