Adding Columns in 2D array (Python)

Question

So I am trying to add all the columns of a 2D array except for the first two columns of the array. If the sum of the row is greater than or equal to 9 and less than 12, I want the function to print the row. Here is a sample of my 2D array that is a list of lists:

[[12606.000,  74204.000,     1.000,     1.000,     1.000,     1.000,     1.000,     0.000,     0.000],        
[12606.000,  105492.000,     0.000,     0.000,     0.000,     0.000,     0.000,     0.000,     1.000],    
[12606.000,  112151.000,     1.000,     1.000,     0.000,     0.000,     0.000,     0.000,     0.000],     
[12606.000,  121896.000,     0.000,     0.000,     0.000,     0.000,     0.000,     1.000,     0.000]]

(Some columns were deleted for formatting). Here is my code:

def sumBinRow(A):
    """Returns the list of employees recording data for at least nine months and fewer than twelve.
    """
    for i in range(len(A)):
        for j in range(len(A[i])):
            if 9 <= sum(A[i][j+2]) <12:
                print A[i]

I keep getting a "Type Error" saying the 'int' object is not iterable.

I get the same error when I try: "for j in range(12)" as well — user3758443
– user3758443, Commented Jun 23, 2014 at 18:02
So you call your function with the argument being the list of lists above? — Alec
– Alec, Commented Jun 23, 2014 at 18:15
Yes A is the list of lists that is the input of the function — user3758443
– user3758443, Commented Jun 23, 2014 at 18:15

Ngenator · Accepted Answer · 2014-06-23 18:30:36Z

1

Basically, you need to iterate over each list, for each list, take a slice of that list starting from 2, then sum that and do your comparison.

def sumBinRow(A):
    """Prints the list of employees recording data for at least nine months and fewer than twelve.
    """
    for row in A:
        if 9 <= sum(row[2:]) < 12:
            print row

or in 1 line cause why not :P

def sumBinRow(A):
    """Prints the list of employees recording data for at least nine months and fewer than twelve.
    """
    print [row for row in A if 9 <= sum(row[2:]) < 12]

edited Jun 23, 2014 at 18:30

answered Jun 23, 2014 at 18:25

Ngenator

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1 Comment

moooeeeep Over a year ago

Was going to suggest just the same thing. Although I'd adapt the name and the docstring to what the function actually does...

DOSHI · Accepted Answer · 2014-06-23 18:18:21Z

0

You should should sum like this.

def sumBinRow(A):
    """Returns the list of employees recording data for at least nine months and fewer than twelve.
    """
    for i in range(len(A)):
        sigma = 0
        for j in range(2,len(A[i])):
            sigma += A[i][j]
            if 9 <= sigma <12:
                print A[i]

answered Jun 23, 2014 at 18:18

DOSHI

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2 Comments

user3758443 Over a year ago

I understand your solution and really like it but for some reason the function is returning rows that have all 1's

user3758443 Over a year ago

[12227.0, 38606.0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1] [12227.0, 38606.0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1] [12227.0, 67307.0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1] [12227.0, 67307.0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]

Saullo G. P. Castro · Accepted Answer · 2014-06-23 18:24:05Z

0

If you use NumPy for this task it would be simpler and much faster:

import numpy as np

a = np.array([[12606.000,  74204.000,     1.000,     1.000,     1.000,     1.000,     1.000,     0.000,     0.000],
              [12606.000,  105492.000,     0.000,     0.000,     0.000,     0.000,     0.000,     0.000,     1.000],
              [12606.000,  112151.000,     1.000,     1.000,     0.000,     0.000,     0.000,     0.000,     0.000],
              [12606.000,  121896.000,     0.000,     0.000,     0.000,     0.000,     0.000,     1.000,     0.000]])

b = a[:, 2:].sum(axis=1)
check = (b >= 9) & (b < 12)
print(a[check])

answered Jun 23, 2014 at 18:24

Saullo G. P. Castro

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Comments

bcorso · Accepted Answer · 2014-06-23 18:47:39Z

0

The problem is that you are trying to sum over something that is not an array:

if 9 <= sum(A[i][j+2]) <12: // A[j][j+2] is not iterable, it is an int

Instead you want to use the slice function:

if 9 <= sum(A[i][2:]) <12:  // This will sum sum all but first two elements

A more pythonic way would be to use a list comprehension. This can be done with a single line of code:

A = [[12606, 74204 , 1, 1, 1, 1, 1, 0, 0],        
     [12606, 105492, 0, 0, 0, 0, 0, 0, 1],    
     [12606, 112151, 1, 1, 0, 0, 0, 0, 0],     
     [12606, 121896, 0, 0, 0, 0, 0, 1, 0]]

print [row for row in A if 9 <= sum(row[2:]) < 12]

edited Jun 23, 2014 at 18:47

answered Jun 23, 2014 at 18:32

bcorso

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