Rewrite insert() function - list index out of range
I'm essentially trying to re-create a version of the insert() function for a homework assignment.
I've written the following function:
def insert_value(my_list, value, insert_position):
list_copy =
if insert_position < 0:
insert_position = 0
if insert_position >= len(my_list):
insert_position = len(my_list) - 1
i = 0
while i < len(my_list) + 1:
while i < insert_position:
list_copy.append(my_list[i])
i += 1
while i == insert_position:
list_copy.append(value)
i += 1
while i > insert_position:
list_copy.append(my_list[i-1])
i += 1
return list_copy
I get the error list index out of range for the final while sub-loop, and I can't work out why. The while loop is accounting for the new list length (while i < len(my_list) + 1). What am I missing?
python list insert
edited Nov 18 '18 at 3:24
sjakobi
2,3061432
asked Nov 18 '18 at 2:14
SoundscapeSoundscape
379
add a comment |
I'm essentially trying to re-create a version of the insert() function for a homework assignment.
I've written the following function:
def insert_value(my_list, value, insert_position):
list_copy =
if insert_position < 0:
insert_position = 0
if insert_position >= len(my_list):
insert_position = len(my_list) - 1
i = 0
while i < len(my_list) + 1:
while i < insert_position:
list_copy.append(my_list[i])
i += 1
while i == insert_position:
list_copy.append(value)
i += 1
while i > insert_position:
list_copy.append(my_list[i-1])
i += 1
return list_copy
I get the error list index out of range for the final while sub-loop, and I can't work out why. The while loop is accounting for the new list length (while i < len(my_list) + 1). What am I missing?
python list insert
edited Nov 18 '18 at 3:24
sjakobi
2,3061432
asked Nov 18 '18 at 2:14
SoundscapeSoundscape
379
add a comment |
I'm essentially trying to re-create a version of the insert() function for a homework assignment.
I've written the following function:
def insert_value(my_list, value, insert_position):
list_copy =
if insert_position < 0:
insert_position = 0
if insert_position >= len(my_list):
insert_position = len(my_list) - 1
i = 0
while i < len(my_list) + 1:
while i < insert_position:
list_copy.append(my_list[i])
i += 1
while i == insert_position:
list_copy.append(value)
i += 1
while i > insert_position:
list_copy.append(my_list[i-1])
i += 1
return list_copy
I get the error list index out of range for the final while sub-loop, and I can't work out why. The while loop is accounting for the new list length (while i < len(my_list) + 1). What am I missing?
python list insert
edited Nov 18 '18 at 3:24
sjakobi
2,3061432
asked Nov 18 '18 at 2:14
SoundscapeSoundscape
379
I'm essentially trying to re-create a version of the insert() function for a homework assignment.
I've written the following function:
def insert_value(my_list, value, insert_position):
list_copy =
if insert_position < 0:
insert_position = 0
if insert_position >= len(my_list):
insert_position = len(my_list) - 1
i = 0
while i < len(my_list) + 1:
while i < insert_position:
list_copy.append(my_list[i])
i += 1
while i == insert_position:
list_copy.append(value)
i += 1
while i > insert_position:
list_copy.append(my_list[i-1])
i += 1
return list_copy
I get the error list index out of range for the final while sub-loop, and I can't work out why. The while loop is accounting for the new list length (while i < len(my_list) + 1). What am I missing?
python list insert
python list insert
edited Nov 18 '18 at 3:24
sjakobi
2,3061432
asked Nov 18 '18 at 2:14
SoundscapeSoundscape
379
edited Nov 18 '18 at 3:24
sjakobi
2,3061432
asked Nov 18 '18 at 2:14
SoundscapeSoundscape
379
edited Nov 18 '18 at 3:24
sjakobi
2,3061432
edited Nov 18 '18 at 3:24
sjakobi
2,3061432
edited Nov 18 '18 at 3:24
sjakobi
2,3061432
2,3061432
asked Nov 18 '18 at 2:14
SoundscapeSoundscape
379
asked Nov 18 '18 at 2:14
SoundscapeSoundscape
379
asked Nov 18 '18 at 2:14
SoundscapeSoundscape
379
379
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
Your problem is because you are using those nested while loops which do not exit until their condition is false. So the outer while loop check for i being less then the length of my_list doesn't happen until all nested while loops finish (which it never does). Specifically I think the issue is with the last while loop here:
while i > insert_position:
list_copy.append(my_list[i-1])
i += 1
This while loop will not end because i will always be greater then the insert_position and eventually the i value will be outside the length of your my_list.
If you change your code logic to use if statements inside the while loop I think that will be better and then you only have to increase i once at the end:
i = 0
while i < len(my_list) + 1:
if i < insert_position:
list_copy.append(my_list[i])
elif i == insert_position:
list_copy.append(value)
else:
list_copy.append(my_list[i-1])
i += 1
answered Nov 18 '18 at 2:23
KarlKarl
1,1432516
Marked as solution as it fixed the issue, but it has introduced (or revealed, more likely) a new problem. In the case where an item needs to be added to the end of the list, it adds it to the second last position instead. Why?
– Soundscape
Nov 18 '18 at 2:35
That is because in your check to make sure that the insert position isn't greater then the list, you need to setinsert_position = len(my_list)instead oflen(my_list) - 1. It's wrong because it sets theinsert_positionto be the second to last position instead of the end of the list like you expect.
– Karl
Nov 18 '18 at 2:41
add a comment |
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1 Answer
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1 Answer
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active
oldest
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oldest
votes
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oldest
votes
Your problem is because you are using those nested while loops which do not exit until their condition is false. So the outer while loop check for i being less then the length of my_list doesn't happen until all nested while loops finish (which it never does). Specifically I think the issue is with the last while loop here:
while i > insert_position:
list_copy.append(my_list[i-1])
i += 1
This while loop will not end because i will always be greater then the insert_position and eventually the i value will be outside the length of your my_list.
If you change your code logic to use if statements inside the while loop I think that will be better and then you only have to increase i once at the end:
i = 0
while i < len(my_list) + 1:
if i < insert_position:
list_copy.append(my_list[i])
elif i == insert_position:
list_copy.append(value)
else:
list_copy.append(my_list[i-1])
i += 1
answered Nov 18 '18 at 2:23
KarlKarl
1,1432516
Marked as solution as it fixed the issue, but it has introduced (or revealed, more likely) a new problem. In the case where an item needs to be added to the end of the list, it adds it to the second last position instead. Why?
– Soundscape
Nov 18 '18 at 2:35
That is because in your check to make sure that the insert position isn't greater then the list, you need to setinsert_position = len(my_list)instead oflen(my_list) - 1. It's wrong because it sets theinsert_positionto be the second to last position instead of the end of the list like you expect.
– Karl
Nov 18 '18 at 2:41
add a comment |
Your problem is because you are using those nested while loops which do not exit until their condition is false. So the outer while loop check for i being less then the length of my_list doesn't happen until all nested while loops finish (which it never does). Specifically I think the issue is with the last while loop here:
while i > insert_position:
list_copy.append(my_list[i-1])
i += 1
This while loop will not end because i will always be greater then the insert_position and eventually the i value will be outside the length of your my_list.
If you change your code logic to use if statements inside the while loop I think that will be better and then you only have to increase i once at the end:
i = 0
while i < len(my_list) + 1:
if i < insert_position:
list_copy.append(my_list[i])
elif i == insert_position:
list_copy.append(value)
else:
list_copy.append(my_list[i-1])
i += 1
answered Nov 18 '18 at 2:23
KarlKarl
1,1432516
Marked as solution as it fixed the issue, but it has introduced (or revealed, more likely) a new problem. In the case where an item needs to be added to the end of the list, it adds it to the second last position instead. Why?
– Soundscape
Nov 18 '18 at 2:35
That is because in your check to make sure that the insert position isn't greater then the list, you need to setinsert_position = len(my_list)instead oflen(my_list) - 1. It's wrong because it sets theinsert_positionto be the second to last position instead of the end of the list like you expect.
– Karl
Nov 18 '18 at 2:41
add a comment |
Your problem is because you are using those nested while loops which do not exit until their condition is false. So the outer while loop check for i being less then the length of my_list doesn't happen until all nested while loops finish (which it never does). Specifically I think the issue is with the last while loop here:
while i > insert_position:
list_copy.append(my_list[i-1])
i += 1
This while loop will not end because i will always be greater then the insert_position and eventually the i value will be outside the length of your my_list.
If you change your code logic to use if statements inside the while loop I think that will be better and then you only have to increase i once at the end:
i = 0
while i < len(my_list) + 1:
if i < insert_position:
list_copy.append(my_list[i])
elif i == insert_position:
list_copy.append(value)
else:
list_copy.append(my_list[i-1])
i += 1
answered Nov 18 '18 at 2:23
KarlKarl
1,1432516
Your problem is because you are using those nested while loops which do not exit until their condition is false. So the outer while loop check for i being less then the length of my_list doesn't happen until all nested while loops finish (which it never does). Specifically I think the issue is with the last while loop here:
while i > insert_position:
list_copy.append(my_list[i-1])
i += 1
This while loop will not end because i will always be greater then the insert_position and eventually the i value will be outside the length of your my_list.
If you change your code logic to use if statements inside the while loop I think that will be better and then you only have to increase i once at the end:
i = 0
while i < len(my_list) + 1:
if i < insert_position:
list_copy.append(my_list[i])
elif i == insert_position:
list_copy.append(value)
else:
list_copy.append(my_list[i-1])
i += 1
answered Nov 18 '18 at 2:23
KarlKarl
1,1432516
edited Nov 18 '18 at 4:20
answered Nov 18 '18 at 2:23
KarlKarl
1,1432516
answered Nov 18 '18 at 2:23
KarlKarl
1,1432516
answered Nov 18 '18 at 2:23
KarlKarl
1,1432516
1,1432516
Marked as solution as it fixed the issue, but it has introduced (or revealed, more likely) a new problem. In the case where an item needs to be added to the end of the list, it adds it to the second last position instead. Why?
– Soundscape
Nov 18 '18 at 2:35
That is because in your check to make sure that the insert position isn't greater then the list, you need to setinsert_position = len(my_list)instead oflen(my_list) - 1. It's wrong because it sets theinsert_positionto be the second to last position instead of the end of the list like you expect.
– Karl
Nov 18 '18 at 2:41
add a comment |
Marked as solution as it fixed the issue, but it has introduced (or revealed, more likely) a new problem. In the case where an item needs to be added to the end of the list, it adds it to the second last position instead. Why?
– Soundscape
Nov 18 '18 at 2:35
That is because in your check to make sure that the insert position isn't greater then the list, you need to setinsert_position = len(my_list)instead oflen(my_list) - 1. It's wrong because it sets theinsert_positionto be the second to last position instead of the end of the list like you expect.
– Karl
Nov 18 '18 at 2:41
Marked as solution as it fixed the issue, but it has introduced (or revealed, more likely) a new problem. In the case where an item needs to be added to the end of the list, it adds it to the second last position instead. Why?
– Soundscape
Nov 18 '18 at 2:35
Marked as solution as it fixed the issue, but it has introduced (or revealed, more likely) a new problem. In the case where an item needs to be added to the end of the list, it adds it to the second last position instead. Why?
– Soundscape
Nov 18 '18 at 2:35
That is because in your check to make sure that the insert position isn't greater then the list, you need to set
insert_position = len(my_list) instead of len(my_list) - 1. It's wrong because it sets the insert_position to be the second to last position instead of the end of the list like you expect.– Karl
Nov 18 '18 at 2:41
That is because in your check to make sure that the insert position isn't greater then the list, you need to set
insert_position = len(my_list) instead of len(my_list) - 1. It's wrong because it sets the insert_position to be the second to last position instead of the end of the list like you expect.– Karl
Nov 18 '18 at 2:41
add a comment |
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