# Pandas how to find column contains a certain value

In this tutorial, we will learn how to find the index of a column that contains a certain value.

Example we have a dataframe with the following columns:

```
import pandas as pd
df = pd.DataFrame({
'A': [1, 4, 7, 1, 4],
'B': [2, 5, 8, 2, 5],
'C': [3, 6, 9, 3, 6]
})
```

```
A B C
0 1 2 3
1 4 5 6
2 7 8 9
4 1 2 3
5 4 5 6
```

Let us find the index of the column that contains the value `5`

.

Using np.where from numpy

The numpy function `np.where`

can be used to find the index of a column that contains a certain value.
The syntax is:
`numpy.where(condition[, x, y])`

```
Parameters
conditionarray_like, bool
Where True, yield x, otherwise yield y.
x, y: array_like
Values from which to choose. x, y and condition need to be broadcastable to some shape.
Returns
out: ndarray
An array with elements from x where condition is True, and elements from y elsewhere.
```

For the above example, we can use the following code to find the index of the column `B`

that contains the value `5`

.

```
import numpy as np
col_index = pd.DataFrame(np.where(df.eq(5))[1] + 1, columns=['col_index'])
```

Output:

```
col_index
0 2
1 2
```