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Tag: scipy

Python-Scipy sparse Matrices – what is A[i, j] doing?

According to my previous question here (Python – Multiply sparse matrix row with non-sparse vector by index) direct indexing of sparse matrices is not possible (at least not if you don’t want to work with the three arrays by which the sparse.csr matrix is defined, data, indices, indptr). But I just found out, that given a csr-sparse matrix A, this

Generating constraints for optimization in scipy using loop

There are lots of constraints which I will use in optimization using scipy; so I need to generate the constraints by loop. Below there’s a sample of my constraints: There constraints are more than three… I use following loop to generate but I couldn’t get the same output. Answer You are updating cons everytime. Try this And this is more

can’t understand scipy.sparse.csr_matrix example

I can’t wrap my head around csr_matrix examples in scipy documentation: https://docs.scipy.org/doc/scipy/reference/generated/scipy.sparse.csr_matrix.html Can someone explain how this example work? I believe this is following this format. csr_matrix((data, (row_ind, col_ind)), [shape=(M, N)]) where data, row_ind and col_ind satisfy the relationship a[row_ind[k], col_ind[k]] = data[k]. What is a here? Answer This is a sparse matrix. So, it stores the explicit indices and

Loading Matlab files into Python

I am attempting to understand the difference between loading a data file into Python and into Matlab in order to translate some code. I have a line of code that goes: When I run the code in Matlab I know that the data is in workspace. There is a 224×501 double called datalib and a 501×29 double called names. The

loading EMNIST-letters dataset

I have been trying to find a way to load the EMNIST-letters dataset but without much success. I have found interesting stuff in the structure and can’t wrap my head around what is happening. Here is what I mean: I downloaded the .mat format in here I can load the data using it is a dictionnary with the keys as

Scipy.signal.spectrogram output lengths

I am trying to analyze the frequencies of a song at certain points of time held inside an array. I am using the scipy.signal.spectrogram function to generate those frequencies. the length of the song is 2:44, or 164 seconds, and the sampling rate of the scipy.wavfile read is 44100. When I use spectrogram: The length of f is really small,

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