Python map object is not subscriptable

Question

Why does the following script give the error:

payIntList[i] = payIntList[i] + 1000 TypeError: 'map' object is not subscriptable

payList = []
numElements = 0

while True:
        payValue = raw_input("Enter the pay amount: ")
        numElements = numElements + 1
        payList.append(payValue)
        choice = raw_input("Do you wish to continue(y/n)?")
        if choice == 'n' or choice == 'N':
                         break

payIntList = map(int,payList)

for i in range(numElements):
         payIntList[i] = payIntList[i] + 1000
         print payIntList[i]

Asked By: station

||

Source

Answer 1

map() doesn’t return a list, it returns a map object.

You need to call list(map) if you want it to be a list again.

Even better,

from itertools import imap
payIntList = list(imap(int, payList))

Won’t take up a bunch of memory creating an intermediate object, it will just pass the ints out as it creates them.

Also, you can do if choice.lower() == 'n': so you don’t have to do it twice.

Python supports +=: you can do payIntList[i] += 1000 and numElements += 1 if you want.

If you really want to be tricky:

from itertools import count
for numElements in count(1):
    payList.append(raw_input("Enter the pay amount: "))
    if raw_input("Do you wish to continue(y/n)?").lower() == 'n':
         break

and / or

for payInt in payIntList:
    payInt += 1000
    print payInt

Also, four spaces is the standard indent amount in Python.

Answered By: agf

Answer 2

In Python 3, map returns an iterable object of type map, and not a subscriptible list, which would allow you to write map[i]. To force a list result, write

payIntList = list(map(int,payList))

However, in many cases, you can write out your code way nicer by not using indices. For example, with list comprehensions:

payIntList = [pi + 1000 for pi in payList]
for pi in payIntList:
    print(pi)

Answered By: phihag

Answer 3

Don’t need to use range for this problem in pypy3 or python3, so it is actually less code..

for i in payIntList: print ( i + 1000 )

and coincidentally matches RustyTom’s comment in PhiHag’s solution above. Note : Can not reference a map using array brackets [] in pypy3 or python3 or it will throw the same error.

payIntList[i]

Map ref caused the error.

Answered By: Joseph Poirier

Answer 4

i’m trying to change an old script to python3.

for i in range(numframes): frameOneChannel[i] = frameInt[4*i+1]*2**8+frameInt[4*i]#separate and store in new list if frameOneChannel[i] > 2**15: frameOneChannel[i] = (frameOneChannel[i]-2**16)

and after reading this thread, i thought the error would be solved by adding list(map)

for i in range(numframes): frameOneChannel[i] = list(map(int,frameInt[4*i+1]*2**8+frameInt[4*i]))#separate and store in new list if frameOneChannel[i] > 2**15: frameOneChannel[i] = (frameOneChannel[i]-2**16)

but alas that did result in the same error.

can somebody help me to understand and solve this?

Answered By: user74341

Python map object is not subscriptable

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