python - Pandas expand rows from list data available in column

Question

I have a data frame like this in pandas:

 column1      column2
 [a,b,c]        1
 [d,e,f]        2
 [g,h,i]        3

Expected output:

column1      column2
  a              1
  b              1
  c              1
  d              2
  e              2
  f              2
  g              3
  h              3
  i              3

How to process this data ?

Answer 1

DataFrame.explode

Since pandas >= 0.25.0 we have the explode method for this, which expands a list to a row for each element and repeats the rest of the columns:

df.explode('column1').reset_index(drop=True)

Output

  column1  column2
0       a        1
1       b        1
2       c        1
3       d        2
4       e        2
5       f        2
6       g        3
7       h        3
8       i        3

---

Since pandas >= 1.1.0 we have the ignore_index argument, so we don't have to chain with reset_index:

df.explode('column1', ignore_index=True)

Output

  column1  column2
0       a        1
1       b        1
2       c        1
3       d        2
4       e        2
5       f        2
6       g        3
7       h        3
8       i        3