I have this dataframe df1 of 8 rows:
ID
A
B
C
D
E
F
G
H
And I have this array arr of size 4 [-1, 0, 1, 2], and an m = 2, so I want to assign the values of this array jumping m times to df1, so I can have eventually:
ID N
A -1
B -1
C 0
D 0
E 1
F 1
G 2
H 2
How to do that in Python?
CodePudding user response：
df1=pd.DataFrame({'ID':['A','B', 'C', 'D', 'E', 'F', 'G', 'H']})
arr=[-1,0,1,2]
m=2
If arr should be repeated again and again:
df1['N']=(arr*m)[:len(df1)]
Result:
| ID | N | |
|---|---|---|
| 0 | A | -1 |
| 1 | B | 0 |
| 2 | C | 1 |
| 3 | D | 2 |
| 4 | E | -1 |
If each element should be repeated:
df1['N']=[arr[i] for i in range(len(arr)) for j in range(m)][:len(df1)]
Result:
| ID | N | |
|---|---|---|
| 0 | A | -1 |
| 1 | B | -1 |
| 2 | C | 0 |
| 3 | D | 0 |
| 4 | E | 1 |
CodePudding user response：
~~ Without numpy
arr = [-1, 0, 1, 2]
m = 2
df1["N"] = sum([[x]*m for x in arr], [])
~~ With Numpy
import numpy as np
arr = [-1, 0, 1, 2]
m = 2
df1["N"] = np.repeat(arr, m)
Output:
ID N
0 A -1
1 B -1
2 C 0
3 D 0
4 E 1
5 F 1
6 G 2
7 H 2