how to insert a element at specific index in python list

Question

I am creating a list whose items are to be mapped by index number. I tried using the list.insert() method. But still it always adds the first element to 0th index and I want the first element at 1st index. For example:

somelist=[]
somelist.insert(1,"Jack")
somelist.insert(2,"Nick")
somelist.insert(3,"Daniel")

>>print(somelist[1])
Nick # not Jack

how can I do this in Python? where I can insert element only at given index and let the list start from index 1.

list.inset() is not a "inser at an index" instead it is "insert before(or at) the index", somelist.insert(1,"Jack") will insert at first at index 0 because no eleemnt exists before 1 index — Grijesh Chauhan
– Grijesh Chauhan, Commented Dec 27, 2018 at 6:38
Why would you not just index the list with n - 1 if your n is one based? Why are you really trying to shift the list elements? — Mad Physicist
– Mad Physicist, Commented Dec 27, 2018 at 6:50
instead of adding None at 0th index, better to change print(somelist[1]) to print(somelist[0]) — Grijesh Chauhan
– Grijesh Chauhan, Commented Dec 27, 2018 at 6:54

Jim Todd · Accepted Answer · 2018-12-27 06:40:45Z

6

When you insert something into a empty list, it will always be starting from the first position. Do something like this as workaround:

somelist=[]
somelist.insert(0,"dummy")
somelist.insert(1,"Jack")
somelist.insert(2,"Nick")
somelist.insert(3,"Daniel")

#print(somelist[1])
print(somelist[1])

output:

Jack

answered Dec 27, 2018 at 6:40

Jim Todd

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J...S · Accepted Answer · 2018-12-27 06:56:47Z

3

I think a dictionary could be helpful here if that will do.

Like

d={}

and insertion at required places is as easy as

d[1]="Jack"
d[2]="Nick"
d[3]="Daniel"

Now

print( d[1] )

will print

Jack

This way you won't have to use dummy values.

answered Dec 27, 2018 at 6:56

J...S

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1 Comment

Mad Physicist Over a year ago

This is much better than using dummy elements, which make a list much less iterable.

cazjonoli · Accepted Answer · 2018-12-27 06:40:03Z

1

Your somelist array is empty, which means you can't add an item to the index 1 if there is no item in index 0..

With this i mean when you first try to insert "Jack" to index 1, it goes automatically to index 0, and then you insert "Nick" to index 2, and that goes to index 1... and last you print index 1 which is "Nick"

edited Dec 27, 2018 at 6:40

answered Dec 27, 2018 at 6:36

cazjonoli

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3 Comments

Noob Over a year ago

so should I initialize it with some item?

cazjonoli Over a year ago

Remember that the first item in an array is index 0

Grijesh Chauhan Over a year ago

@MrAlpha Depends, You must first learn what the insert() method do

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