Delete all columns for which value repents consecutively more than 3 times

Question

I have adf that looks like this:

date	stock1	stock2	stock3	stock4	stock5	stock6	stock7	stock8	stock9	stock10
10/20	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9	0.9
11/20	0.1	0.9	0.3	0.4	0.3	0.5	0.3	0.2	0.4	0.1
12/20	0.1	0.6	0.9	0.5	0.6	0.7	0.8	0.7	0.9	0.1
10/20	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9	0.9
11/20	0.8	0.9	0.3	0.4	0.3	0.5	0.3	0.2	0.9	0.1
12/20	0.3	0.6	0.9	0.5	0.6	0.7	0.8	0.7	0.9	0.1
10/20	0.1	0.2	0.3	0.4	0.5	0.7	0.7	0.8	0.9	0.9
11/20	0.8	0.9	0.3	0.4	0.3	0.7	0.3	0.2	0.4	0.1
12/20	0.3	0.6	0.9	0.5	0.6	0.7	0.8	0.7	0.9	0.1

I want to delete all columns for which the same value repeats, consecutively, more than 3 times. In this example, the columns "stock1", "stock6" and "stock9" should be deleted. In the other columns, we have repeating values more than 3 times, but not one after the other. I think I can adapt the code from that question Removing values that repeat more than 5 times in Pandas DataFrame, but I could not manage to do that yet.

Answer 1

You could want avoid apply here:

N = 3
df.loc[:, 
   df.set_index('date')
     .ne(df.shift()).cumsum()
     .stack()
     .groupby(level=1)
     .value_counts()
     .max(level=0).le(N)]