Python 3 - TypeError: 'map' object is not subscriptable

Question

i'm currently running this as a piece of my code for an i/o stream - i'm getting the following error TypeError: 'map' object is not subscriptable for the print (bytest[:10]). What's the proper way run it in Python 3?

with open("/bin/ls", "rb") as fin: #rb as text file and location 
  buf = fin.read()
bytes = map(ord, buf)    
print (bytes[:10])
saveFile = open('exampleFile.txt', 'w')
saveFile.write(bytes)
saveFile.close()

score 6 · Accepted Answer · answered May 08 '17 at 12:14

6

In Python 3 map returns a generator. Try creating a list from it first.

with open("/bin/ls", "rb") as fin: #rb as text file and location 
  buf = fin.read()
bytes = list(map(ord, buf))
print (bytes[:10])
saveFile = open('exampleFile.txt', 'w')
saveFile.write(bytes)
saveFile.close()

If you think that is ugly, you can replace it with a list generator:

bytes = [ord(b) for f in buf]

answered May 08 '17 at 12:14

jdehesa

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2

You could use [**`itertools.islice`**](https://docs.python.org/3/library/itertools.html#itertools.islice) – Peter Wood May 08 '17 at 12:22
@PeterWood Yes, if you only need to read a specific slice once that may be even better. – jdehesa May 08 '17 at 12:25

Python 3 - TypeError: 'map' object is not subscriptable

1 Answers1