Python equivalent of R c() function, for dataframe column indices?

Question

I would like to select from a pandas dataframe specific columns using column index.

In particular, I would like to select columns index by the column index generate

Answer 1

The equivalent is numpy's r_. It combines integer slices without needing to call ranges for each of them:

np.r_[2:4, 7:11, 21:25]
Out: array([ 2,  3,  7,  8,  9, 10, 21, 22, 23, 24])

---

df = pd.DataFrame(np.random.randn(1000))
df.iloc[np.r_[2:4, 7:11, 21:25]]
Out: 
           0
2   2.720383
3   0.656391
7  -0.581855
8   0.047612
9   1.416250
10  0.206395
21 -1.519904
22  0.681153
23 -1.208401
24 -0.358545