How to solve the error 'list assignment index out of range' in python

Question

I try to store the number of weekofyear from the list of data named date_range which stored the data such as

date_range[1] = DatetimeIndex(['2020-03-02', '2020-03-03', '2020-03-04', '2020-03-05',
               '2020-03-06', '2020-03-07', '2020-03-08', '2020-03-09',
               '2020-03-10', '2020-03-11', '2020-03-12', '2020-03-13',
               '2020-03-14', '2020-03-15', '2020-03-16', '2020-03-17',
               '2020-03-18', '2020-03-19', '2020-03-20', '2020-03-21',
               '2020-03-22', '2020-03-23', '2020-03-24', '2020-03-25',
               '2020-03-26', '2020-03-27', '2020-03-28', '2020-03-29',
               '2020-03-30', '2020-03-31', '2020-04-01', '2020-04-02',
               '2020-04-03', '2020-04-04', '2020-04-05'],
              dtype='datetime64[ns]', freq='D')

by using the following code

weeknumber= [] 
for i in range(28): 
    for j in range(35):
        weeknumber[i][j] = pd.Timestamp(date_range[i][j]).weekofyear

However,the IDE show the error 'list assignment index out of range'. How to solve this problem ?

Does this answer ur question: https://stackoverflow.com/questions/64552247/why-is-the-list-index-out-of-range/64552295#64552295 — Sushil, Oct 29 '20 at 03:15

score 1 · Answer 1 · answered Oct 29 '20 at 03:18

When your list is empty in python you can not assign value to unassigned index of list. so you have 2 options here:

Use append like : list.append(value)
make a loop to assign a value to your list before your main for. Like below:

i = 0 
while ( i < index_you_want):
    list[i] = 0
...
#here your main code

score 1 · Accepted Answer · answered Oct 30 '20 at 06:25

Use this:

weeknumber = []
for i in range(28):
    weeknumber.append([])
    for j in range(35)):
        weeknumber[i].append(pd.Timestamp(date_range[i][j]).weekofyear)

For an explanation of why you get surprising results to your other approach, refer to this answer to your other question

How to solve the error 'list assignment index out of range' in python

2 Answers2