how do I check for numbers in a matrix

Question

I need to check if the numbers in gradescale is in my NxM matrix as a numpy array, if example the number 8 is in my matrix, I would like to append the number to a empty list and the row number to another list So how do i check if the number in my matrix isn't in gradescale, i have tried different types of loops, but they dont work.

 wrongNumber = []
 Rows = []
 gradeScale = np.array([-3,0,2,4,7,10,12])
 if there is a number i matrix which is not i gradeScale
     wrongNumber.append[number]
     Rows.append[rownumber]
print("the grade {} in line {} is out of range",format(wrongNumber), 
format(Rows))

How do i find the numbers i my matrix, i cant figure out to make the right loop — Melanie Nielsen, Jun 19 '18 at 12:45

yakobyd · Accepted Answer · 2018-06-19T14:53:20.597

1

You can use numpy.ndarray.shape to go through your rows.

for row in range(matrix.shape[0]):
    for x in matrix[row]:
        if x not in gradeScale:
            wrongNumber.append(x)
            Rows.append(row)

In addition, you do not use format correctly. Your print statement should be

print("The grade {} in line {} is out of range".format(wrongNumber, Rows))

The following post has some more information on formatting String formatting in Python .

Example

import numpy as np

wrongNumber = []
Rows = []

matrix = np.array([[1,2],[3,4],[5,6],[7,8]])
gradeScale = [1,3,4,5,8]

for row in range(matrix.shape[0]):
    for x in matrix[row]:
        if x not in gradeScale:
            wrongNumber.append(x)
            Rows.append(row)

print("The grades {} in lines {} (respectively) are out of range.".format(wrongNumber, Rows))

Output

The grades [2, 6, 7] in lines [0, 2, 3] (respectively) are out of range

edited Jun 19 '18 at 14:53

answered Jun 19 '18 at 12:23

yakobyd

572
4
12

This dosen't work it, i think i have to loop over my matrix instead somehow – Melanie Nielsen Jun 19 '18 at 12:46
Well, as you can see I checked it and it indeed works. What is the format of your matrix? – yakobyd Jun 19 '18 at 12:50
in the example wrong numbers instead should be [2,4] but if I use != instead of == would it mayby work – Melanie Nielsen Jun 19 '18 at 12:51
Ohh, I see you requested for the opposite. – yakobyd Jun 19 '18 at 12:54
Yes it will not work for the opposite case. I will try to update my answer. – yakobyd Jun 19 '18 at 12:58
@MelanieNielsen I have updated my answer. If this solves your question let us clean up this comment section. – yakobyd Jun 19 '18 at 13:05
Thanks it works now! So in the first loop I loop over the rows in the matrix and i the second loop I loop over the elements in the rows? – Melanie Nielsen Jun 19 '18 at 13:10

score 0 · Answer 2 · edited Jun 19 '18 at 14:08

0

Probably a for loop with enumerate() is what you are looking for.

Example:

for rowNumber, number in enumerate(matrix)
    if number not in gradeScale:
        wrongNumber.append[number]
        Rows.append[rowNumber]

edited Jun 19 '18 at 14:08

Ash Sharma

470
3
18

answered Jun 19 '18 at 12:24

eriknayan

1
3

how do I check for numbers in a matrix

2 Answers2

Example

Output