AttributeError: 'numpy.int32' object has no attribute 'append'

Question

First let me show what i want to do.
I have a matrix,

x = [1, 2, 1, 2, 3, 3, 2, 3, 1, 2]

All i want do is to select position of repeated numbers in the array and print it in a matrix x_new where :

x_new[0]= [0,2,8] (for similar position of repeated 1's in x)  
x_new[1]=[1,3,6,9](for similar position of repeated 2's in x)  
x_new[2]=[4,5,7] (for similar position of repeated 3's in x)

Until now what i have done is :

a=[]      
x=m[:,3]  #x=np.array([1, 2, 1, 2, 3, 3, 2, 3, 1, 2])     
ss=set([i for i in x if sum([1 for a in x if a == i]) > 1])     
lenss=len(ss)      
for ln in range(lenss):    
    for k in range(10):      
        if(x[k]== list(ss)[ln]):    
            print k     
        a.append(ln)    
    print 'next'

But at the a.append line it's showing:

'numpy.int32' object has no attribute 'append'

Can anyone please tell me how to overcome this error? Thanks

Anand S Kumar · Accepted Answer · 2015-09-08 07:14:23Z

5

In Python 2.x , the variables you use inside list comprehension leak into the surrounding namespace, so the a variable you use in the list comprehension -

ss=set([i for i in x if sum([1 for a in x if a == i]) > 1])

Changes the a variable you defined as list to elements of x.

Example for this -

>>> i
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'i' is not defined
>>> s = [i for i in range(5)]
>>> i
4

You should use different name inside the list comprehensin , and it would help if you use more meaningful names for your variables, that would reduce the risk of running into such issues.

This issue should not occur in Python 3.x , as in Python 3.x , list comphrehension has a namespace of its own.

answered Sep 8, 2015 at 7:14

Anand S Kumar

91.4k18 gold badges196 silver badges179 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Sayantan Mukherjee Over a year ago

oops sorry...got you. Let me check. Thanks a lot

Nader Hisham · Accepted Answer · 2015-09-08 08:41:41Z

3

this is numpy solution to your problem

x = np.array(x)
unique = np.unique(x)
[np.where(x == unique_num) for unique_num in unique]

edited Sep 8, 2015 at 8:41

answered Sep 8, 2015 at 8:36

Nader Hisham

5,4144 gold badges22 silver badges35 bronze badges

Comments

Sdwdaw · Accepted Answer · 2015-09-08 07:21:16Z

1

You reassign your variable a: In the first line a=[], but you use again a in ss generator:

ss=set([i for i in x if sum([1 for a in x if a == i]) > 1])

Simple example:

>>> [x for x in range(10)]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> x
9
>>>

answered Sep 8, 2015 at 7:21

Sdwdaw

1,0377 silver badges14 bronze badges

1 Comment

Sayantan Mukherjee Over a year ago

oops sorry...got you. Let me check. Thanks a lot

Collectives™ on Stack Overflow

AttributeError: 'numpy.int32' object has no attribute 'append'

3 Answers 3

1 Comment

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related