Avoiding unpacking an array when altering its dimension
$begingroup$
I am trying to flatten a matrix from 3-dimensional to 2-dimensional one.
The original one has dimension for example {10,120,120}:
list1 = RandomReal[1, {10, 120, 120}];
I want to convert it to a new matrix with {10,120*120} dimension. I am using:
On["Packing"] (*For checking if exist unpacked arrays *)
Flatten[Map[Flatten, {list1}, {-3}], 1];
But this will generate unpacked array. How should I avoid this issue?
list-manipulation packed-arrays
$endgroup$
add a comment |
$begingroup$
I am trying to flatten a matrix from 3-dimensional to 2-dimensional one.
The original one has dimension for example {10,120,120}:
list1 = RandomReal[1, {10, 120, 120}];
I want to convert it to a new matrix with {10,120*120} dimension. I am using:
On["Packing"] (*For checking if exist unpacked arrays *)
Flatten[Map[Flatten, {list1}, {-3}], 1];
But this will generate unpacked array. How should I avoid this issue?
list-manipulation packed-arrays
$endgroup$
2
$begingroup$
TryFlatten[list1, {{1}, {2, 3}}]
.
$endgroup$
– J. M. is computer-less♦
1 hour ago
$begingroup$
Thanks, it works!
$endgroup$
– cj9435042
1 hour ago
$begingroup$
Flatten /@ list1
$endgroup$
– Okkes Dulgerci
33 mins ago
add a comment |
$begingroup$
I am trying to flatten a matrix from 3-dimensional to 2-dimensional one.
The original one has dimension for example {10,120,120}:
list1 = RandomReal[1, {10, 120, 120}];
I want to convert it to a new matrix with {10,120*120} dimension. I am using:
On["Packing"] (*For checking if exist unpacked arrays *)
Flatten[Map[Flatten, {list1}, {-3}], 1];
But this will generate unpacked array. How should I avoid this issue?
list-manipulation packed-arrays
$endgroup$
I am trying to flatten a matrix from 3-dimensional to 2-dimensional one.
The original one has dimension for example {10,120,120}:
list1 = RandomReal[1, {10, 120, 120}];
I want to convert it to a new matrix with {10,120*120} dimension. I am using:
On["Packing"] (*For checking if exist unpacked arrays *)
Flatten[Map[Flatten, {list1}, {-3}], 1];
But this will generate unpacked array. How should I avoid this issue?
list-manipulation packed-arrays
list-manipulation packed-arrays
edited 1 hour ago
m_goldberg
87.2k872197
87.2k872197
asked 2 hours ago
cj9435042cj9435042
35416
35416
2
$begingroup$
TryFlatten[list1, {{1}, {2, 3}}]
.
$endgroup$
– J. M. is computer-less♦
1 hour ago
$begingroup$
Thanks, it works!
$endgroup$
– cj9435042
1 hour ago
$begingroup$
Flatten /@ list1
$endgroup$
– Okkes Dulgerci
33 mins ago
add a comment |
2
$begingroup$
TryFlatten[list1, {{1}, {2, 3}}]
.
$endgroup$
– J. M. is computer-less♦
1 hour ago
$begingroup$
Thanks, it works!
$endgroup$
– cj9435042
1 hour ago
$begingroup$
Flatten /@ list1
$endgroup$
– Okkes Dulgerci
33 mins ago
2
2
$begingroup$
Try
Flatten[list1, {{1}, {2, 3}}]
.$endgroup$
– J. M. is computer-less♦
1 hour ago
$begingroup$
Try
Flatten[list1, {{1}, {2, 3}}]
.$endgroup$
– J. M. is computer-less♦
1 hour ago
$begingroup$
Thanks, it works!
$endgroup$
– cj9435042
1 hour ago
$begingroup$
Thanks, it works!
$endgroup$
– cj9435042
1 hour ago
$begingroup$
Flatten /@ list1
$endgroup$
– Okkes Dulgerci
33 mins ago
$begingroup$
Flatten /@ list1
$endgroup$
– Okkes Dulgerci
33 mins ago
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
An alternative to using Flatten
as in the comments is to use ArrayReshape
. For large arrays, ArrayReshape
should be significantly faster. For example:
list1 = RandomReal[1, {10, 1200, 1200}];
Comparison:
r1 = Flatten[list1, {{1}, {2, 3}}]; //RepeatedTiming
r2 = ArrayReshape[list1, {10, 1200 1200}]; //RepeatedTiming
r1 === r2
{0.120, Null}
{0.025, Null}
True
$endgroup$
$begingroup$
I'm too slow..... :)
$endgroup$
– Michael E2
1 hour ago
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
An alternative to using Flatten
as in the comments is to use ArrayReshape
. For large arrays, ArrayReshape
should be significantly faster. For example:
list1 = RandomReal[1, {10, 1200, 1200}];
Comparison:
r1 = Flatten[list1, {{1}, {2, 3}}]; //RepeatedTiming
r2 = ArrayReshape[list1, {10, 1200 1200}]; //RepeatedTiming
r1 === r2
{0.120, Null}
{0.025, Null}
True
$endgroup$
$begingroup$
I'm too slow..... :)
$endgroup$
– Michael E2
1 hour ago
add a comment |
$begingroup$
An alternative to using Flatten
as in the comments is to use ArrayReshape
. For large arrays, ArrayReshape
should be significantly faster. For example:
list1 = RandomReal[1, {10, 1200, 1200}];
Comparison:
r1 = Flatten[list1, {{1}, {2, 3}}]; //RepeatedTiming
r2 = ArrayReshape[list1, {10, 1200 1200}]; //RepeatedTiming
r1 === r2
{0.120, Null}
{0.025, Null}
True
$endgroup$
$begingroup$
I'm too slow..... :)
$endgroup$
– Michael E2
1 hour ago
add a comment |
$begingroup$
An alternative to using Flatten
as in the comments is to use ArrayReshape
. For large arrays, ArrayReshape
should be significantly faster. For example:
list1 = RandomReal[1, {10, 1200, 1200}];
Comparison:
r1 = Flatten[list1, {{1}, {2, 3}}]; //RepeatedTiming
r2 = ArrayReshape[list1, {10, 1200 1200}]; //RepeatedTiming
r1 === r2
{0.120, Null}
{0.025, Null}
True
$endgroup$
An alternative to using Flatten
as in the comments is to use ArrayReshape
. For large arrays, ArrayReshape
should be significantly faster. For example:
list1 = RandomReal[1, {10, 1200, 1200}];
Comparison:
r1 = Flatten[list1, {{1}, {2, 3}}]; //RepeatedTiming
r2 = ArrayReshape[list1, {10, 1200 1200}]; //RepeatedTiming
r1 === r2
{0.120, Null}
{0.025, Null}
True
answered 1 hour ago
Carl WollCarl Woll
68.9k391177
68.9k391177
$begingroup$
I'm too slow..... :)
$endgroup$
– Michael E2
1 hour ago
add a comment |
$begingroup$
I'm too slow..... :)
$endgroup$
– Michael E2
1 hour ago
$begingroup$
I'm too slow..... :)
$endgroup$
– Michael E2
1 hour ago
$begingroup$
I'm too slow..... :)
$endgroup$
– Michael E2
1 hour ago
add a comment |
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2
$begingroup$
Try
Flatten[list1, {{1}, {2, 3}}]
.$endgroup$
– J. M. is computer-less♦
1 hour ago
$begingroup$
Thanks, it works!
$endgroup$
– cj9435042
1 hour ago
$begingroup$
Flatten /@ list1
$endgroup$
– Okkes Dulgerci
33 mins ago