Adding/appending a loop to the end of another a loop

Question

I want to add a loop to the end of another loop. But all I've tried failed and I don't know what to do

I've tried

for i in range(2):
   print i
   for r in range(4, 6):
     print i.append(r)

and

for i in range(2):
   print i
   print i.append(4,5)

I expected:

But I received the following error instead:

Error for the 1st code sample:

Traceback:(most recent call last):
  File "main.py", line 4, in <module>
    print i.append(r)
AttributeError: 'int object has no attribute 'append'

Error for the 2nd code sample:

Traceback:(most recent call last):
  File "main.py", line 4, in <module>
    print i.append(4, 5)
AttributeError: 'int object has no attribute 'append'

range() gives you a list of integers, and iterating over that gives you each integer. Integers are not lists, so you can't append to them. What is it you're trying to accomplish? — Fred Larson
– Fred Larson, Commented Aug 1, 2019 at 18:59
And when you append to a list, the returned value is simply None, so nothing would print anyway. i = list(); for _ in range(2): for r in range(4, 6): i.append(r) — Alexander
– Alexander, Commented Aug 1, 2019 at 19:01
Create an empty list at before for loop, then append i, then add another separate for loop for r and append r to i using i.append(r) — Drees
– Drees, Commented Aug 1, 2019 at 19:01

Jab · Accepted Answer · 2019-08-01 19:35:12Z

4

If all you're trying to do is print all values of 2 ranges in succession then just add them together.

for i in range(2) + range(4, 6):
   print i

Results are as follows:

For Python3 you must either wrap the ranges in list or for a more elegant and forward compatible solution use using itertools.chain it combines both ranges making them one iterable.

for i in chain(range(2), range(4, 6)):
   print(i)

If what you're trying to do is make both ranges into a list then chain works as well:

list(chain(range(2), range(4, 6)))
#[0, 1, 4, 5]

Or just add them together

#py2
range(2) + range(4, 6)
#py3
list(range(2)) + list(range(4, 6))

edited Aug 1, 2019 at 19:35

answered Aug 1, 2019 at 19:05

Jab

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7 Comments

Fred Larson Over a year ago

Or just plain range(2) + range(4, 6) does the same thing.

Jab Over a year ago

True, I've been using Python3 for way too long.

Fred Larson Over a year ago

For Python3, you could do list(range(2)) + list(range(4, 6))

Chris_Rands Over a year ago

@FredLarson the chain() method is better (more memory efficient) and Python 2's lifetime is almost over

Jab Over a year ago

Yes you could although I do prefer the chain method as the line is more readable and efficient plus allows for more ranges

|

Drees · Accepted Answer · 2019-08-01 19:09:27Z

2

The other answers are good as well, but if you are expecting a list, this is what you would want to try to do without using imports.

lst = []
for i in range(2):
   lst.append(i)
for r in range(4, 6):
   lst.append(r)
print lst

answered Aug 1, 2019 at 19:09

Drees

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Comments

quamrana · Accepted Answer · 2019-08-01 19:03:32Z

1

This code produces the output you seem to require:

for i in range(2):
   print i
for r in range(4, 6):
  print r

answered Aug 1, 2019 at 19:03

quamrana

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4 Comments

Drees Over a year ago

I think he is requesting a single list for both i and r values

quamrana Over a year ago

What makes you say that? The expected output seems clear.

Drees Over a year ago

Only because of the .append in his code. I may be mistaken though.

quamrana Over a year ago

Ok, I see what you did there. Your answer deserves an up-vote, even though the output is not as requested.

Rakesh007 · Accepted Answer · 2019-08-01 19:10:49Z

-1

your code doesn't work becoz i is a value in the first for loop and you can't append a value to a value.

Below for loops will get your desired result

for i in range(2):
   print(i)
for r in range(4, 6):
    print(r)

answered Aug 1, 2019 at 19:10

Rakesh007

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