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?
>>> row = np.array([0, 0, 1, 2, 2, 2])
>>> col = np.array([0, 2, 2, 0, 1, 2])
>>> data = np.array([1, 2, 3, 4, 5, 6])
>>> csr_matrix((data, (row, col)), shape=(3, 3)).toarray()
array([[1, 0, 2],
[0, 0, 3],
[4, 5, 6]])
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?
python scipy
asked Nov 11 '18 at 23:00
AerinAerin
3,76143458
add a comment |
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?
>>> row = np.array([0, 0, 1, 2, 2, 2])
>>> col = np.array([0, 2, 2, 0, 1, 2])
>>> data = np.array([1, 2, 3, 4, 5, 6])
>>> csr_matrix((data, (row, col)), shape=(3, 3)).toarray()
array([[1, 0, 2],
[0, 0, 3],
[4, 5, 6]])
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?
python scipy
asked Nov 11 '18 at 23:00
AerinAerin
3,76143458
1
ais the matrix.
– Warren Weckesser
Nov 11 '18 at 23:44
add a comment |
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?
>>> row = np.array([0, 0, 1, 2, 2, 2])
>>> col = np.array([0, 2, 2, 0, 1, 2])
>>> data = np.array([1, 2, 3, 4, 5, 6])
>>> csr_matrix((data, (row, col)), shape=(3, 3)).toarray()
array([[1, 0, 2],
[0, 0, 3],
[4, 5, 6]])
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?
python scipy
asked Nov 11 '18 at 23:00
AerinAerin
3,76143458
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?
>>> row = np.array([0, 0, 1, 2, 2, 2])
>>> col = np.array([0, 2, 2, 0, 1, 2])
>>> data = np.array([1, 2, 3, 4, 5, 6])
>>> csr_matrix((data, (row, col)), shape=(3, 3)).toarray()
array([[1, 0, 2],
[0, 0, 3],
[4, 5, 6]])
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?
python scipy
python scipy
asked Nov 11 '18 at 23:00
AerinAerin
3,76143458
asked Nov 11 '18 at 23:00
AerinAerin
3,76143458
edited Nov 12 '18 at 2:04
Aerin
asked Nov 11 '18 at 23:00
AerinAerin
3,76143458
asked Nov 11 '18 at 23:00
AerinAerin
3,76143458
asked Nov 11 '18 at 23:00
AerinAerin
3,76143458
3,76143458
1
ais the matrix.
– Warren Weckesser
Nov 11 '18 at 23:44
add a comment |
1
ais the matrix.
– Warren Weckesser
Nov 11 '18 at 23:44
1
1
a is the matrix.– Warren Weckesser
Nov 11 '18 at 23:44
a is the matrix.– Warren Weckesser
Nov 11 '18 at 23:44
add a comment |
2 Answers
2
active
oldest
votes
This is a sparse matrix. So, it stores the explicit indices and values at those indices. So for example, since row=0 and col=0 corresponds to 1 (the first entries of all three arrays in your example). Hence, the [0,0] entry of the matrix is 1. And so on.
answered Nov 12 '18 at 2:14
Rohit PandeyRohit Pandey
98151639
add a comment |
As far as I understand, in row and col arrays we have indices which corrensponds to non-zero values in matrix. a[0, 0] = 1, a[0, 2] = 2, a[1, 2] = 3 and so on. As we have no indices for a[0, 1], a[1, 0], a[1, 1] so appropriate values in matrix are equal to 0.
Also, maybe this little intro will be helpful for you:
https://www.youtube.com/watch?v=Lhef_jxzqCg
answered Jan 24 at 9:55
AutoRunAutoRun
12
add a comment |
Your Answer
StackExchange.ifUsing("editor", function ()
StackExchange.using("externalEditor", function ()
StackExchange.using("snippets", function ()
StackExchange.snippets.init();
);
);
, "code-snippets");
StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "1"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);
else
createEditor();
);
function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);
);
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53254104%2fcant-understand-scipy-sparse-csr-matrix-example%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
This is a sparse matrix. So, it stores the explicit indices and values at those indices. So for example, since row=0 and col=0 corresponds to 1 (the first entries of all three arrays in your example). Hence, the [0,0] entry of the matrix is 1. And so on.
answered Nov 12 '18 at 2:14
Rohit PandeyRohit Pandey
98151639
add a comment |
This is a sparse matrix. So, it stores the explicit indices and values at those indices. So for example, since row=0 and col=0 corresponds to 1 (the first entries of all three arrays in your example). Hence, the [0,0] entry of the matrix is 1. And so on.
answered Nov 12 '18 at 2:14
Rohit PandeyRohit Pandey
98151639
add a comment |
This is a sparse matrix. So, it stores the explicit indices and values at those indices. So for example, since row=0 and col=0 corresponds to 1 (the first entries of all three arrays in your example). Hence, the [0,0] entry of the matrix is 1. And so on.
answered Nov 12 '18 at 2:14
Rohit PandeyRohit Pandey
98151639
This is a sparse matrix. So, it stores the explicit indices and values at those indices. So for example, since row=0 and col=0 corresponds to 1 (the first entries of all three arrays in your example). Hence, the [0,0] entry of the matrix is 1. And so on.
answered Nov 12 '18 at 2:14
Rohit PandeyRohit Pandey
98151639
answered Nov 12 '18 at 2:14
Rohit PandeyRohit Pandey
98151639
answered Nov 12 '18 at 2:14
Rohit PandeyRohit Pandey
98151639
answered Nov 12 '18 at 2:14
Rohit PandeyRohit Pandey
98151639
98151639
add a comment |
add a comment |
As far as I understand, in row and col arrays we have indices which corrensponds to non-zero values in matrix. a[0, 0] = 1, a[0, 2] = 2, a[1, 2] = 3 and so on. As we have no indices for a[0, 1], a[1, 0], a[1, 1] so appropriate values in matrix are equal to 0.
Also, maybe this little intro will be helpful for you:
https://www.youtube.com/watch?v=Lhef_jxzqCg
answered Jan 24 at 9:55
AutoRunAutoRun
12
add a comment |
As far as I understand, in row and col arrays we have indices which corrensponds to non-zero values in matrix. a[0, 0] = 1, a[0, 2] = 2, a[1, 2] = 3 and so on. As we have no indices for a[0, 1], a[1, 0], a[1, 1] so appropriate values in matrix are equal to 0.
Also, maybe this little intro will be helpful for you:
https://www.youtube.com/watch?v=Lhef_jxzqCg
answered Jan 24 at 9:55
AutoRunAutoRun
12
add a comment |
As far as I understand, in row and col arrays we have indices which corrensponds to non-zero values in matrix. a[0, 0] = 1, a[0, 2] = 2, a[1, 2] = 3 and so on. As we have no indices for a[0, 1], a[1, 0], a[1, 1] so appropriate values in matrix are equal to 0.
Also, maybe this little intro will be helpful for you:
https://www.youtube.com/watch?v=Lhef_jxzqCg
answered Jan 24 at 9:55
AutoRunAutoRun
12
As far as I understand, in row and col arrays we have indices which corrensponds to non-zero values in matrix. a[0, 0] = 1, a[0, 2] = 2, a[1, 2] = 3 and so on. As we have no indices for a[0, 1], a[1, 0], a[1, 1] so appropriate values in matrix are equal to 0.
Also, maybe this little intro will be helpful for you:
https://www.youtube.com/watch?v=Lhef_jxzqCg
answered Jan 24 at 9:55
AutoRunAutoRun
12
edited Jan 24 at 10:25
answered Jan 24 at 9:55
AutoRunAutoRun
12
answered Jan 24 at 9:55
AutoRunAutoRun
12
answered Jan 24 at 9:55
AutoRunAutoRun
12
12
add a comment |
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53254104%2fcant-understand-scipy-sparse-csr-matrix-example%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
1
ais the matrix.– Warren Weckesser
Nov 11 '18 at 23:44