How to keep using values from a list until the diagonal of a matrix is full using itertools
So I am trying to use a smaller list to populate the diagonal of a larger matrix. I thought using the cycle function in itertools would make this an easy task but I can't seem to get it to work. Here is what I tried
a = np.zeros((10,10))
b = [1, 2, 3, 4, 5]
for i in range(len(a.shape[0])):
a[i, i] = list(itertools.cycle(b))
but this makes it endlessly iterate. I am hoping that it will stop once the diagonal has been filled. Other options that are more pythonic are greatly appreciated!
python-3.x matrix list-comprehension itertools diagonal
asked Nov 19 '18 at 20:10
Amanda.pyAmanda.py
354
add a comment |
So I am trying to use a smaller list to populate the diagonal of a larger matrix. I thought using the cycle function in itertools would make this an easy task but I can't seem to get it to work. Here is what I tried
a = np.zeros((10,10))
b = [1, 2, 3, 4, 5]
for i in range(len(a.shape[0])):
a[i, i] = list(itertools.cycle(b))
but this makes it endlessly iterate. I am hoping that it will stop once the diagonal has been filled. Other options that are more pythonic are greatly appreciated!
python-3.x matrix list-comprehension itertools diagonal
asked Nov 19 '18 at 20:10
Amanda.pyAmanda.py
354
what are you trying? to set the diags to 1 then 2, then 3 etc ?
– Patrick Artner
Nov 19 '18 at 20:15
add a comment |
So I am trying to use a smaller list to populate the diagonal of a larger matrix. I thought using the cycle function in itertools would make this an easy task but I can't seem to get it to work. Here is what I tried
a = np.zeros((10,10))
b = [1, 2, 3, 4, 5]
for i in range(len(a.shape[0])):
a[i, i] = list(itertools.cycle(b))
but this makes it endlessly iterate. I am hoping that it will stop once the diagonal has been filled. Other options that are more pythonic are greatly appreciated!
python-3.x matrix list-comprehension itertools diagonal
asked Nov 19 '18 at 20:10
Amanda.pyAmanda.py
354
So I am trying to use a smaller list to populate the diagonal of a larger matrix. I thought using the cycle function in itertools would make this an easy task but I can't seem to get it to work. Here is what I tried
a = np.zeros((10,10))
b = [1, 2, 3, 4, 5]
for i in range(len(a.shape[0])):
a[i, i] = list(itertools.cycle(b))
but this makes it endlessly iterate. I am hoping that it will stop once the diagonal has been filled. Other options that are more pythonic are greatly appreciated!
python-3.x matrix list-comprehension itertools diagonal
python-3.x matrix list-comprehension itertools diagonal
asked Nov 19 '18 at 20:10
Amanda.pyAmanda.py
354
asked Nov 19 '18 at 20:10
Amanda.pyAmanda.py
354
edited Nov 19 '18 at 20:52
Amanda.py
asked Nov 19 '18 at 20:10
Amanda.pyAmanda.py
354
asked Nov 19 '18 at 20:10
Amanda.pyAmanda.py
354
asked Nov 19 '18 at 20:10
Amanda.pyAmanda.py
354
354
what are you trying? to set the diags to 1 then 2, then 3 etc ?
– Patrick Artner
Nov 19 '18 at 20:15
add a comment |
what are you trying? to set the diags to 1 then 2, then 3 etc ?
– Patrick Artner
Nov 19 '18 at 20:15
what are you trying? to set the diags to 1 then 2, then 3 etc ?
– Patrick Artner
Nov 19 '18 at 20:15
what are you trying? to set the diags to 1 then 2, then 3 etc ?
– Patrick Artner
Nov 19 '18 at 20:15
add a comment |
1 Answer
1
active
oldest
votes
you mean to use itertools.cycle, not repeat. The latter repeats the element (the list), good luck setting that into a value, specially if you force iteration (since it runs forever)
I'd create a reference on a cycle object outside the loop and assign a value to the diagonal iterating over it manually (the only proper way with cycle). Also note that your loop range was wrong. a.shape[0] is a dimension, no need for len
import numpy as np,itertools
a = np.zeros((10,10))
b = [1, 2, 3, 4, 5]
iterator = itertools.cycle(b)
for i in range(a.shape[0]):
a[i, i] = next(iterator)
result:
>>> a
array([[ 1., 0., 0., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 2., 0., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 3., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 4., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 5., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 1., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 2., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 3., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 0., 4., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 0., 0., 5.]])
As they loop forever, cycle and repeat should not be used in a context of forced iteration (repeat has an optional parameter to limit the repeats, though).
answered Nov 19 '18 at 20:15
Jean-François FabreJean-François Fabre
104k955112
I mean't to put cycle in my original post, oops. But my issue was that I wasn't using it as an iterator outside the loop and not using next! Thank you.
– Amanda.py
Nov 19 '18 at 20:25
those are evil "infinite loop" twins when misused :)
– Jean-François Fabre
Nov 19 '18 at 20:27
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
you mean to use itertools.cycle, not repeat. The latter repeats the element (the list), good luck setting that into a value, specially if you force iteration (since it runs forever)
I'd create a reference on a cycle object outside the loop and assign a value to the diagonal iterating over it manually (the only proper way with cycle). Also note that your loop range was wrong. a.shape[0] is a dimension, no need for len
import numpy as np,itertools
a = np.zeros((10,10))
b = [1, 2, 3, 4, 5]
iterator = itertools.cycle(b)
for i in range(a.shape[0]):
a[i, i] = next(iterator)
result:
>>> a
array([[ 1., 0., 0., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 2., 0., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 3., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 4., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 5., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 1., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 2., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 3., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 0., 4., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 0., 0., 5.]])
As they loop forever, cycle and repeat should not be used in a context of forced iteration (repeat has an optional parameter to limit the repeats, though).
answered Nov 19 '18 at 20:15
Jean-François FabreJean-François Fabre
104k955112
I mean't to put cycle in my original post, oops. But my issue was that I wasn't using it as an iterator outside the loop and not using next! Thank you.
– Amanda.py
Nov 19 '18 at 20:25
those are evil "infinite loop" twins when misused :)
– Jean-François Fabre
Nov 19 '18 at 20:27
add a comment |
you mean to use itertools.cycle, not repeat. The latter repeats the element (the list), good luck setting that into a value, specially if you force iteration (since it runs forever)
I'd create a reference on a cycle object outside the loop and assign a value to the diagonal iterating over it manually (the only proper way with cycle). Also note that your loop range was wrong. a.shape[0] is a dimension, no need for len
import numpy as np,itertools
a = np.zeros((10,10))
b = [1, 2, 3, 4, 5]
iterator = itertools.cycle(b)
for i in range(a.shape[0]):
a[i, i] = next(iterator)
result:
>>> a
array([[ 1., 0., 0., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 2., 0., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 3., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 4., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 5., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 1., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 2., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 3., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 0., 4., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 0., 0., 5.]])
As they loop forever, cycle and repeat should not be used in a context of forced iteration (repeat has an optional parameter to limit the repeats, though).
answered Nov 19 '18 at 20:15
Jean-François FabreJean-François Fabre
104k955112
I mean't to put cycle in my original post, oops. But my issue was that I wasn't using it as an iterator outside the loop and not using next! Thank you.
– Amanda.py
Nov 19 '18 at 20:25
those are evil "infinite loop" twins when misused :)
– Jean-François Fabre
Nov 19 '18 at 20:27
add a comment |
you mean to use itertools.cycle, not repeat. The latter repeats the element (the list), good luck setting that into a value, specially if you force iteration (since it runs forever)
I'd create a reference on a cycle object outside the loop and assign a value to the diagonal iterating over it manually (the only proper way with cycle). Also note that your loop range was wrong. a.shape[0] is a dimension, no need for len
import numpy as np,itertools
a = np.zeros((10,10))
b = [1, 2, 3, 4, 5]
iterator = itertools.cycle(b)
for i in range(a.shape[0]):
a[i, i] = next(iterator)
result:
>>> a
array([[ 1., 0., 0., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 2., 0., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 3., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 4., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 5., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 1., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 2., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 3., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 0., 4., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 0., 0., 5.]])
As they loop forever, cycle and repeat should not be used in a context of forced iteration (repeat has an optional parameter to limit the repeats, though).
answered Nov 19 '18 at 20:15
Jean-François FabreJean-François Fabre
104k955112
you mean to use itertools.cycle, not repeat. The latter repeats the element (the list), good luck setting that into a value, specially if you force iteration (since it runs forever)
I'd create a reference on a cycle object outside the loop and assign a value to the diagonal iterating over it manually (the only proper way with cycle). Also note that your loop range was wrong. a.shape[0] is a dimension, no need for len
import numpy as np,itertools
a = np.zeros((10,10))
b = [1, 2, 3, 4, 5]
iterator = itertools.cycle(b)
for i in range(a.shape[0]):
a[i, i] = next(iterator)
result:
>>> a
array([[ 1., 0., 0., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 2., 0., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 3., 0., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 4., 0., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 5., 0., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 1., 0., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 2., 0., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 3., 0., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 0., 4., 0.],
[ 0., 0., 0., 0., 0., 0., 0., 0., 0., 5.]])
As they loop forever, cycle and repeat should not be used in a context of forced iteration (repeat has an optional parameter to limit the repeats, though).
answered Nov 19 '18 at 20:15
Jean-François FabreJean-François Fabre
104k955112
edited Nov 19 '18 at 20:28
answered Nov 19 '18 at 20:15
Jean-François FabreJean-François Fabre
104k955112
answered Nov 19 '18 at 20:15
Jean-François FabreJean-François Fabre
104k955112
answered Nov 19 '18 at 20:15
Jean-François FabreJean-François Fabre
104k955112
104k955112
I mean't to put cycle in my original post, oops. But my issue was that I wasn't using it as an iterator outside the loop and not using next! Thank you.
– Amanda.py
Nov 19 '18 at 20:25
those are evil "infinite loop" twins when misused :)
– Jean-François Fabre
Nov 19 '18 at 20:27
add a comment |
I mean't to put cycle in my original post, oops. But my issue was that I wasn't using it as an iterator outside the loop and not using next! Thank you.
– Amanda.py
Nov 19 '18 at 20:25
those are evil "infinite loop" twins when misused :)
– Jean-François Fabre
Nov 19 '18 at 20:27
I mean't to put cycle in my original post, oops. But my issue was that I wasn't using it as an iterator outside the loop and not using next! Thank you.
– Amanda.py
Nov 19 '18 at 20:25
I mean't to put cycle in my original post, oops. But my issue was that I wasn't using it as an iterator outside the loop and not using next! Thank you.
– Amanda.py
Nov 19 '18 at 20:25
those are evil "infinite loop" twins when misused :)
– Jean-François Fabre
Nov 19 '18 at 20:27
those are evil "infinite loop" twins when misused :)
– Jean-François Fabre
Nov 19 '18 at 20:27
add a comment |
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what are you trying? to set the diags to 1 then 2, then 3 etc ?
– Patrick Artner
Nov 19 '18 at 20:15