Extracting vectors from a dataframe using a Boolean matrix

I have a dataframe that looks something like this:

df = pd.DataFrame(np.random.rand(10,3), columns = ['col1', 'col2', 'col3'])

and I have another matrix which is a Boolean matrix that looks something like this:

b_matrix = pd.DataFrame(np.array([[0,1,1],
                       [1,1,0],
                       [0,0,1],
                       [0,1,0]]),                                             
                       columns = ['col1', 'col2', 'col3'],
                       index = ['input1', 'input2', 'input3', 'input4'])

So the idea here is that I will provide some input, this will be checked against b_matrix and then I will have returned to me only the corresponding columns of df. e.g. if the input is input1 then the output will be df[['col2', 'col3']]:

I can think of a way to do this with keeping a static list of the column names to check over each time but I was wondering if there was a more direct method?

>Solution :

You can use input to take user input and df.loc:

In [1076]: inp = input('User input:')
User input:input1

In [1077]: df[b_matrix.columns[b_matrix.loc[inp].eq(1)]]
Out[1077]: 
       col2      col3
0  0.179902  0.832655
1  0.444187  0.487146
2  0.879333  0.756792
3  0.870601  0.661337
4  0.082169  0.008669
5  0.190734  0.975966
6  0.839718  0.290976
7  0.862724  0.426222
8  0.581909  0.333300
9  0.949953  0.539106

If you choose input2:

In [1080]: inp = input('User input:')
User input:input2

In [1081]: df[b_matrix.columns[b_matrix.loc[inp].eq(1)]]
Out[1081]: 
       col1      col2
0  0.072600  0.179902
1  0.126708  0.444187
2  0.646533  0.879333
3  0.673643  0.870601
4  0.313205  0.082169
5  0.951917  0.190734
6  0.076799  0.839718
7  0.294087  0.862724
8  0.240569  0.581909
9  0.851999  0.949953