Equivalent of 'ismember' from Matlab in Python? [duplicate]

This question already has answers here: Python equivalent of MATLAB's "ismember" function (5 answers) 开发者_JAVA技巧 Closed 2 years ago.

I am trying to perform a comparison between the rows of two matrices A and B with the same number of columns.

In matlab the command ismember(a, b, 'rows') returns a vector containing 1 where the rows of A are also rows of B and 0 otherwise, and also returns the highest index in B for each element in A that is a member of B.

[tf, index] = ismember(A, B, 'rows');

Is there an equivalent function in python? Any ideas how to do it?

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you can get your vector as

same_rows = [a == b for a,b in zip(A, B)]

Note that this will yield True and False instead of 1 and 0 but bool is subclassed from int and True == 1 and False == 0.

to get the max row where this occurs, you can just use

max_row = next(i for i, row in enumerate(reversed(same_rows)) if row == True)

If you want the number of rows that they have in common, you can just use

same_count == sum(same_rows)

Note that this is all for python and assumes that matrices are lists of lists or tuples or tuples of lists or tuples. HTH.

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The ismember library can be helpful.

pip install ismember

Example:

# Import library
from ismember import ismember

# Example with random matrices
a_vec = np.random.randint(0,10,(5,8))
b_vec = np.random.randint(0,10,(5,10))

# Row-wise comparison
Iloc, idx = ismember(a_vec, b_vec, 'rows')

# These should all be True
for i in np.arange(0,a_vec.shape[0]):
    np.all(a_vec[i,Iloc[i]]==b_vec[i,idx[i]])