I have a matrix like this
t = np.array([[1,2,3,'foo'], [2,3,4,'bar'], [5,6,7,'hello'], [8,9,1,'bar']])I want to get the indices where the rows contain the string 'bar'
In a 1d array
rows = np.where(t == 'bar')should give me the indices [0,3] followed by broadcasting:-
results = t[rows]should give me the right rows
But I can't figure out how to get it to work with 2d arrays.
32 Answers
You have to slice the array to the col you want to index:
rows = np.where(t[:,3] == 'bar')
result = t1[rows]This returns:
[[2,3,4,'bar'], [8,9,1,'bar']]For the general case, where your search string can be in any column, you can do this:
>>> rows, cols = np.where(t == 'bar')
>>> t[rows]
array([['2', '3', '4', 'bar'], ['8', '9', '1', 'bar']], dtype='|S11')
