how can i delete an element in numpy array and use a for loop in python and its index

Question

This is what I made and it doesn't work, I made a for loop and I use it to get the index and use it in another thing why doesn't it work or can I found another method to delete the element and use the index of it.

Here is some of my code

X1_train, X1_test, y1_train, y1_test = train_test_split(EclipseFeautres, EclipseClass, test_size=0.3, random_state=0)
E_critical_class=y1_train.copy()
E_critical_class = E_critical_class[E_critical_class != 1]
for x in range(len(E_critical_class)):
if(E_critical_class[x]==1):
    E=np.delete(E_critical_class,x)

The delete result is assigned to E, but that variable isn't used anywhere. So changes that you make in one loop are just thrown away. In general though it is a bad idea to delete items one by one in a loop, even when working with lists. The array/list size changes with deletes. It would be better to collect a list of delete locations, and call np.delete just once with that list. — hpaulj
– hpaulj, Commented Jun 18, 2020 at 0:51
@hpaulj i get what u said but i'm asking this question because I need the same index to delete another elements in another numpy array and I use E list to print it but it doesn't work — habiba
– habiba, Commented Jun 18, 2020 at 2:17

Valdi_Bo · Accepted Answer · 2020-06-18 06:58:28Z

2

Your task is something like filtering of an array. You want to drop all elements == 1.

Assume that the source array (arr) contains:

array([0, 1, 2, 3, 4, 1, 0, 3, 7, 1])

so it contains 3 elements == 1 (to be dropped).

A much simpler way to do it is to use boolean indexing and save the result back to the original variable:

arr = arr[arr != 1]

The result is:

array([0, 2, 3, 4, 0, 3, 7])

as you wish - with all ones dropped.

answered Jun 18, 2020 at 6:58

Valdi_Bo

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Erdal Bozkurt · Accepted Answer · 2021-06-26 13:41:27Z

0

#dizi icinde olan ve kendini tekrarlayan sayiyi delete etme!!!!!!
#to delete the repeated element in the numpy array
import numpy as np
a = np.array([10, 0, 0, 20, 0, 30, 40, 50, 0, 60, 70, 80, 90, 100,0])
print("Original array:")
print(a)
index=np.zeros(0)
print("index=",index)
for i in range(len(a)):
    if a[i]==0:
        index=np.append(index, i)
print("index=",index)
new_a=np.delete(a,index)
print("new_a=",new_a)

answered Jun 26, 2021 at 13:41

Erdal Bozkurt

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