Looping through 2d array removing elements, indexing error, python

Question

I am trying to delete empty elements of a list named report info split but keep getting list out of range errors.

The list looks similar to this :

reportinfosplit = [[1,,g,5,44,f][1,5,4,f,g,,g]]

I have found many answers to this for 1d arrays but not 2d. Is there a way to prevent the index from going out of range? The list elements are not all the same size, and I thought that was the reason, but it kept happening after I made them the same length.

for i in range(len(reportinfosplit)):
    for j in range(len(reportinfosplit[i])):
        if(j<=len(reportinfosplit[i])):
            if reportinfosplit[i][j] == "":
                del reportinfosplit[i][j]

if(j<=len(reportinfosplit[i])) -> if(j<len(reportinfosplit[i])) might do the trick — FlyingTeller
– FlyingTeller, Commented Mar 12, 2018 at 7:17

cs95 · Accepted Answer · 2018-03-13 06:28:23Z

2

You can use filter to remove empty values from list

reportinfosplit = [[1,"","g",5,44,"f"],[1,5,4,"f","g","","g"]]
print([filter(None, i) for i in reportinfosplit])     #Python3 print([list(filter(None, i)) for i in reportinfosplit])

Output:

[[1, 'g', 5, 44, 'f'], [1, 5, 4, 'f', 'g', 'g']]

edited Mar 13, 2018 at 6:28

cs95

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answered Mar 12, 2018 at 7:18

Rakesh

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1 Comment

Rakesh Over a year ago

Added snippet for python3. Thanks

JahKnows · Accepted Answer · 2018-03-12 07:20:39Z

0

Using list comprehensions

reportinfosplit = [[1,"",'g',5,44,'f'],[1,5,4,'f','g',"",'g']]

for ix, i in enumerate(reportinfosplit):
    reportinfosplit[ix] = [val for val in i if val != '']

print(reportinfosplit)

[[1, 'g', 5, 44, 'f'], [1, 5, 4, 'f', 'g', 'g']]

answered Mar 12, 2018 at 7:20

JahKnows

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4 Comments

lolcats4u Over a year ago

I definitely like this solution and it works. I have always found list comprehensions difficult to read though, which is why I've had issues using them. I am currently learning python 3 transitioning from C++. I really appreciate the help!

JahKnows Over a year ago

Yeah they definitely take a moment to get used to. This goes through each row. Then the list comprehension, creates a new list which includes all the values except those that are ''.

lolcats4u Over a year ago

Can you tell me more about what it means by ix? Is x just another variable in the nested loop in this case? If it is, why is it so many people use x instead of j. I was always told to use i, j, k instead of x, y, z

JahKnows Over a year ago

@MakennaSophiaHerl the for loop with enumerate outputs both the index of the instance and the instance itself. These variables can have any name you desire. I chose ix for index and i for the item.

FlyingTeller · Accepted Answer · 2018-03-12 07:20:43Z

0

You are checking j for j<=len(reportinfosplit[i]), which results in j being able to become as large as the current length of reportinfosplit[i] (which is possible, since the current length of reportinfosplit[i] changes). Try it like this:

for i in range(len(reportinfosplit)):
    for j in range(len(reportinfosplit[i])):
        if(j<len(reportinfosplit[i])):
            if reportinfosplit[i][j] == "":
                del reportinfosplit[i][j]

answered Mar 12, 2018 at 7:20

FlyingTeller

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