Is there way to use Python Pandas to subtract a specific row from another row?-CodePudding

Portion of my code that's giving trouble below. I open a CSV and want to subtract the 1st row from the last row then append it to a new file. I get an error KeyError: 96 when I try it. I know the problem is the df[96]-df

CodePudding user response：

You can use iloc to select the first and last row and then subtract

import pandas as pd
import numpy as np

#Create a test df
np.random.seed(1)
df = pd.DataFrame({
    'col1':np.random.choice(10,6),
    'col2':np.random.choice(10,6),
    'col3':np.random.choice(10,6),
})

#subtract the first row from the last row
first_ind = 0
last_ind = len(df)-1
diff_row = df.iloc[last_ind]-df.iloc[first_ind]
print(diff_row)

Here's the test df that is created:

   col1  col2  col3
0     5     1     5
1     8     7     2
2     9     6     4
3     5     9     2
4     0     2     4
5     0     4     7

And then diff_row equals:

col1   -5
col2    3
col3    2
dtype: int64