Python: Return column index given a condition is met

Question

I would like to fetch the column indices given that they meet a certain condition.

For instance, I would like to fetch the indices of all columns that contain 0. In this case, it would be [0,1] --> (column A and column B).

df = {'A': [0,1,2,3,4,5], 
      'B': [3,4,0,5,6,5], 
      'C': [1,2,3,4,5,6],
      'D': [7,8,9,8,7,6]} 

df = pd.DataFrame(df)

Thanks!

user_15438033 · Answer

Use np.where:

index_array = np.where(df.eq(0).any())[0] # prints array([0, 1])
index_array = np.where(~df.eq(0).any())[0]  # prints array([2, 3])

In case if you need column names:

col_list = df.columns[df.eq(0).any()] # prints Index(['A', 'B'], dtype='object')

user_12449445 · Answer

This should help you out.

(df == 0).any(axis=1)
op:
0     True
1    False
2     True
3    False
4    False
5    False
dtype: bool