2

I have a multidimensional array such as this:

[["asdf","bmnl", "123","456,"0","999","1234","3456"],["qwer","tyui","789","657,"122","9","673","1"]]

However, in the multidimensional array, only the last 6items of each array are needed and the first two are not needed. How can I remove the first two pieces of data from each of the arrays within the multidimensional array so it would look like:

[["123","456,"0","999","1234","3456"],["789","657,"122","9","673","1"]]

So far, I have done this:

list1 = []
list2 = []
for row in rows:
    list1.append(row[0].split(',')) #to put the split list into the top i i.e. [["asdf","bmnl", "123","456,"0","999","1234","3456"]["qwer","tyui","789","657,"122","9","673","1"]]
for i in list1:
    for index in len(list1):
        if index >=2:
             list2.append(index) #this does not work and causes errors

How could I go about fixing this so the output would be:

[["123","456,"0","999","1234","3456"],["789","657,"122","9","673","1"]]

Thanks

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5 Answers 5

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4

Just use a list comprehension and grab every element from index 2 and beyond in each sublist:

>>> array = [["asdf","bmnl", "123","456","0","999","1234","3456"],["qwer","tyui","789","657","122","9","673","1"]]
>>> [sublist[2:] for sublist in array]
[['123', '456', '0', '999', '1234', '3456'], ['789', '657', '122', '9', '673', '1']]
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3 
lst = [["asdf","bmnl", "123","456","0","999","1234","3456"],["qwer","tyui","789","657","122","9","673","1"]]
for i in lst:
    del i[0:2] #deleting 0 and 1 index from each list

print lst
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2

This is a typical use case for a list comprehension:

list2 = [item[2:] for item in list1]
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2

You can use a list comprehension like below:

[item[2:] for item in my_list]

item[2:] called list slicing, and it means that for each sub-list of my_list, we take items from the index 2 till the last item.

Output:

>>> my_list = [["asdf", "bmnl", "123", "456", "0", "999", "1234", "3456"], ["qwer", "tyui", "789", "657", "122", "9", "673", "1"]]
>>>
>>> [item[2:] for item in my_list]
[['123', '456', '0', '999', '1234', '3456'], ['789', '657', '122', '9', '673', '1']]
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0 
start = [["asdf","bmnl", "123","456","0","999","1234","3456"],
         ["qwer","tyui","789","657","122","9","673","1"]]

list_1, list_2 = [i[2:] for i in start] # I use list comprehension to create a multidimensional 
                                        # list that contains slices of each object in the base 
                                        # list and unwrap it to list_1 and list_2

Same as

n_list = [] #create an empty new list
for i in start: #loop through the origional
    n_list.append(i[2:]) #append slices of each item to the new list
list_1, list_2 = n_list #unwrap the list
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1 Comment

Please include some explanation to go with code so others can understand how it works

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