I am trying this simple code to search in an array and replace the elements that are greater than 1 to 1:
import numpy as np
j = np.array([[1],[3],[1],[0],[9]])
for x in j:
if abs(x) > 1 :
j[x] = 1
But I get such errors:
IndexError: index 9 is out of bounds for axis 0 with size 5
If all you're doing is making all values if absolute(j[i]) is greater than 1 to 1 then numpy has this capability built in and it's so simple it can be done in one line and more efficient than any python loop:
j[np.absolute(j) > 1] = 1
To show you how this would work:
#made 3 a negitive value to prove absolute works.
j = np.array([[1],[-3],[1],[0],[9]])
j[np.absolute(j) > 1] = 1
j is now:
[[1]
[1]
[1]
[0]
[1]]
When you traverse an array in a for loop you are actually accessing the elements, not the index. After all, you are comparing x against 1. You can retrieve the index in many ways, one of the common ones is to use enumerate, like so:
import numpy as np
j = np.array([[1],[3],[1],[0],[9]])
for i,x in enumerate(j): # i is the index, x is the value
if abs(x) > 1 :
j[i] = 1
Try to change the for loop using enumerate to :
import numpy as np
j = np.array([[1],[3],[1],[0],[9]])
for i,x in enumerate(j):
if abs(x) > 1 :
j[i] = 1
as you see in your error output
IndexError: index 9 is out of bounds for axis 0 with size 5
you are trying to update a value at index 9 but your array is of size 5. which clearly means you are not using the index of array but actually the value at index.
enumerate your array and run a loop with both index & value
for i,x in enumerate(j):
if abs(x) > 1 :
j[i] = 1
Are you trying to make a two dimensional array? You have your elements in brackets within brackets "[[1],[3],[1],[0],[9]]" .... also, you're iterating over values, not indices: x is an array value "[3]" not an index "1".
Change to:
import numpy as np
j = np.array([1,3,1,0,9])
# Keep track of index starting at 0
i = 0
for x in j:
if abs(x) > 1 :
# change value at index i
j[i] = 1
# increment index
i += 1
You may want to replace the for statement with this:
for x in range(len(j))
enumerate, and use the enumerated index to change the element.