Pandas combining sparse columns in dataframe

Question

I am using Python, Pandas for data analysis. I have sparsely distributed data in different columns like following

| id | col1a | col1b | col2a | col2b | col3a         


        

Answer 1

Another alternative with pd.wide_to_long

m = pd.wide_to_long(df,['col'],'id','j',suffix='\d+\w+').reset_index()

(m.join(pd.DataFrame(m.pop('j').agg(list).tolist()))
  .assign(group=lambda x:x[0].radd('g'))
  .set_index(['id','group',1])['col'].unstack().dropna()
  .rename_axis(None,axis=1).add_prefix('col').reset_index())

---

   id group cola colb
0   1    g1   11   12
1   2    g2   21   86
2   3    g1   22   87
3   4    g3  545   32