How to select first N rows and last row in Python Pandas?-CodePudding

Problem: Select first N rows and last row in Python Pandas.

only gets 1 row which is index 9 and last row.

df.iloc[[(9),-1]]

I thought I could get using head and last row but not working.

df.iloc[[head(9),-1]]

Target output: 0 1 2 3 up to 9 last row

CodePudding user response：

head = df.head(9)
tail = df.tail(1)
df = head.append(tail)

I think you just want this. Please clarify if this is wrong.

Output:

    first_column  second_column
0              0              0
1              1              1
2              2              2
3              3              3
4              4              4
5              5              5
6              6              6
7              7              7
8              8              8
12            12             12

This is assuming I understand correctly, you want 9 rows and also the last.

CodePudding user response：

You could use numpy.concatenate:

import numpy as np
out = df.iloc[np.r_[0:9, -1]]

or just list concatenation:

out = df.iloc[list(range(9)) [-1]]

Test:

For a DataFrame:

df = pd.DataFrame({'a':range(20), 'b':range(100,120)})

the output:

     a    b
0    0  100
1    1  101
2    2  102
3    3  103
4    4  104
5    5  105
6    6  106
7    7  107
8    8  108
19  19  119