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I want to convert a matrix to a list python

Answer 1

A:

The best way to do it is:

result = map(tuple, Matrix)

aaronasterling 2010-10-29 03:41:14

@gotgenes, correct on both counts. I updated. I generally forget about `chain.from_iterable`. Thanks for the reminder.

aaronasterling 2010-10-29 04:22:23

I understand downvoting when I misunderstood the question (which didn't happen), but why has the only answer that actually creates a list of tuples been downvoted _after_ I fixed it? Is it because I look like a hippie? If it makes you feel any better (and not that it's any of your damn business) but I've been shaving at least once every two months and am currently wearing a polo. I'm just too much of a lazy hippie to update my picture.

aaronasterling 2010-10-29 04:39:37

@aaronsterling Perhaps the down-voter was the lazy one, reading my two comments and without checking the updated code for correctness? I have removed my earlier two comments since this code is correct (making some assumption about the structure of `Matrix`, which is ill-defined by the OP).

gotgenes 2010-10-29 13:52:43

@aaronsterling - Remind me to never post a picture of myself here if looking like a hippie gets you downvoted! :) At any rate I'm not sure why you got downvoted, either... (+1 from me) Your answer is the only one that actually gives a list of tuples. I'm leaving mine up just because `ndarray.tolist()` is useful to know about, even it it produces nested lists.

Joe Kington 2010-10-29 16:06:03

Answer 2

+1 A:

Is this a numpy matrix? If so, just use the tolist() method. E.g.:

import numpy as np
x = np.matrix([[1,2,3],
               [7,1,3],
               [9,4,3]])
y = x.tolist()

This yields:

y --> [[1, 2, 3], [7, 1, 3], [9, 4, 3]]

Joe Kington 2010-10-29 03:41:54

Answer 3

A:

if you are using numpy and you want to just traverse the matrix as a list then you can just

from numpy import array
m = [[  1.   6.  13.  10.   2.]
 [  2.   9.  10.  13.  15.]
 [  3.  15.  13.  14.  16.]
 [  4.   5.  14.  13.   6.]
 [  5.  18.  16.   4.   3.]
 [  6.   7.  12.  18.   3.]
 [  7.   1.   8.  17.  11.]
 [  8.  14.   5.   4.  16.]
 [  9.  16.  18.  17.  15.]
 [ 10.   8.   9.  15.  17.]
 [ 11.  11.  17.  18.  12.]]

for x in array(m).flat:
   print x

This will not consume extra memory

fabrizioM 2010-10-29 03:45:19

It also flattens the array, which isn't want the OP wanted (I think?). Regardless, you're quite correct in pointing out that there's no need to convert it to a list if you just want to iterate over it. Simply iterating over the array itself will group the rows, as the OP seems to want.

Joe Kington 2010-10-29 03:55:25

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I want to convert a matrix to a list python

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