can anybody help me to create a Dataframe in python with for loop: I want to create a Dataframe from two lists: list1 and list of lists (list2) where the length of list1 = the number of sublists in list2: an example: list1= ["A", "B", "C", "D"] list2= [[1, 2, 3, 4], [1, 3, 4, 6, 7], [2, 3, 4, 5, 6], [2, 4, 5, 7, 8]]=>

my goal is to add/ iterate the values in list1  to matching the values in each sublist in list2 attached (and see belwo) is my final target/wished table:
| Col1     | Col2     |
| -------- | -------- |
| A        | 1  
| A        | 2 
  A          3
  A          4
  B          1
  B          3
  B          4
  B          6
  B          7

Thank you in advance for answering my questions.

CodePudding user response：

Try:

list1 = ["A", "B", "C", "D"]
list2 = [[1, 2, 3, 4], [1, 3, 4, 6, 7], [2, 3, 4, 5, 6], [2, 4, 5, 7, 8]]

df = pd.DataFrame(zip(list1, list2), columns=["Col1", "Col2"]).explode("Col2")
print(df)

Prints:

  Col1 Col2
0    A    1
0    A    2
0    A    3
0    A    4
1    B    1
1    B    3
1    B    4
1    B    6
1    B    7
2    C    2
2    C    3
2    C    4
2    C    5
2    C    6
3    D    2
3    D    4
3    D    5
3    D    7
3    D    8

CodePudding user response：

Using numpy.repeat and a list comprehension:

import numpy as np

df = pd.DataFrame({'Col1': np.repeat(list1, list(map(len, list2))),
                   'Col2': [x for l in list2 for x in l]})

Output:

   Col1  Col2
0     A     1
1     A     2
2     A     3
3     A     4
4     B     1
5     B     3
6     B     4
7     B     6
8     B     7
9     C     2
10    C     3
11    C     4
12    C     5
13    C     6
14    D     2
15    D     4
16    D     5
17    D     7
18    D     8

CodePudding user response：

Creating a dataframe from lists can be done this way:

df = pd.DataFrame(list(zip(list1, list2)),
               columns =['list1_name', 'list2_name'])

Or this way as a dictionary

df = pd.DataFrame(data = {“list1”: list1, “list2”: list2})