How do I get "The numbers" Only at the end? - python-2.7

Question

Here is what I want to get:
$ python ex33.py
At the top i is 0
Numbers now: [0]
At the bottom i is 1
At the top i is 1
Numbers now: [0, 1]
At the bottom i is 2
At the top i is 2
Numbers now: [0, 1, 2]
At the bottom i is 3
At the top i is 3
Numbers now: [0, 1, 2, 3]
At the bottom i is 4
At the top i is 4
Numbers now: [0, 1, 2, 3, 4]
At the bottom i is 5
At the top i is 5
Numbers now: [0, 1, 2, 3, 4, 5]
At the bottom i is 6
The numbers:
0
1
2
3
4
5
This was a while loop:
1 i = 0
2 numbers = []
3
4 while i < 6:
5 print "At the top i is %d" % i
6 numbers.append(i)
7
8 i = i + 1
9 print "Numbers now: ", numbers
10 print "At the bottom i is %d" % i
11
12
13 print "The numbers: "
14
15 for num in numbers:
16 print num
Now Mr Shaw asks me to build this into a function. His exact question is: Convert this while- loop to a function that you can call, and replace 6 in the test (i < 6) with a variable. I am not sure I have build a function (since those mostly start with a def? Or do they always start with a def?)
I am not sure if I understand completely what he is asking, but this is what I did:
i = 0
numbers = []
for i in range (0, 6):
print "At the top i is %d" % i
numbers.append(i)
i = i + 1
print "Numbers now: ", numbers
print "At the bottom i is %d" % i
print "The numbers: "
for num in numbers:
print num
Which actually makes me kind of proud for how for I have gotten with this:
At the top i is 0
Numbers now: [0]
At the bottom i is 1
The numbers:
0
At the top i is 1
Numbers now: [0, 1]
At the bottom i is 2
The numbers:
0
1
At the top i is 2
Numbers now: [0, 1, 2]
At the bottom i is 3
The numbers:
0
1
2
At the top i is 3
Numbers now: [0, 1, 2, 3]
At the bottom i is 4
The numbers:
0
1
2
3
At the top i is 4
Numbers now: [0, 1, 2, 3, 4]
At the bottom i is 5
The numbers:
0
1
2
3
4
At the top i is 5
Numbers now: [0, 1, 2, 3, 4, 5]
At the bottom i is 6
The numbers:
0
1
2
3
4
5
Where I am stuck is that "The numbers" is something I only need to get at the end. And that, I can't get my head around. What am I missing (except amazing coding skills and a well functioning brain)?

Answer 1

You have not made a function. While it's not always necessary to use def to make a function, that's the usual way. And I think you've misunderstood what your teacher wanted you to change in your while loop. He wanted you to replace the 6 in the condition i < 6 with a variable (a parameter of the function). You've replaced the while with a for, but still kept the 6 as a constant. Using for loops instead of while loops is often a good idea, but in this case it's now what was being asked for.
As for why your numbers output is being repeated, I suspect it's because that code is inside your main loop now, while it wasn't before. This is not entirely clear though, since you seem to have lost the indentation of the original code when you copied it into Stack Overflow. Since indentation is significant in Python, this makes it hard to know exactly the old code ran.

Answer 2

what you are missing is that in python block of code are defined by the indentation level, you put the part that print the whole list inside the for that fill the list so each time that you put a number in the list also print if afterward. To put that outside reduce the indentation level of that part like this
i = 0
numbers = []
for i in range (0, 6):
print "At the top i is %d" % i
numbers.append(i)
i = i + 1
print "Numbers now: ", numbers
print "At the bottom i is %d" % i
#this part is now outside the for-loop
print "The numbers: "
for num in numbers:
print num
About your other question, yes functions are defined by the key world def you can check the documentation about the details, but in your case you can transform you code into a function very easy like this
def my_function():
i = 0
numbers = []
for i in range (0, 6):
print "At the top i is %d" % i
numbers.append(i)
i = i + 1
print "Numbers now: ", numbers
print "At the bottom i is %d" % i
print "The numbers: "
for num in numbers:
print num
that is, declare that you are creating a new function with the def key world, give it a name, in this case I called my_function, and put your previous code inside it by just give it a extra indentation level as show above.
Functions have the property that they can take a number of arguments and operate according to that, that let you define some behavior and make it more general.
For example: say that you want to print the number 0 to 9 you can do
for num in range(0,10):
print num
Now say that you want to print the number 0-5, 0-20, and 10-20 you can write a similar code for all of them:
for num in range(0,6):
print num
for num in range(0,21):
print num
for num in range(10,21):
print num
but wait there is pattern here all have the same exact code in every case save for the arguments of range, here is when a function come to play, we can define a function that take as arguments 2 numbers and our function do the job of print all the number in between; that is something like this
def my_function(star,stop):
for num in range(star,stop+1): # the +1 is to include the stop number
print num
(this is fun_test.py in the example below)
then we can call our function like this
my_function(0,5)
my_function(0,20)
my_function(10,20)
or if we open the file in a python interpreter or in interactive mode (that is $ python -i ex33.py) we can call with any pair of numbers of our desire
$ python -i fun_test.py
>>> my_function(8,17)
8
9
10
11
12
13
14
15
16
17
>>> my_function(0,5)
0
1
2
3
4
5
>>>
as you can see a function let us re-use a piece of code as many times as we want. The arguments of a function is the part of it that is variable while its code is the behavior we want according to the variable part (if any).
With this little explanation I think that you can modify your function to the requirements that your teacher (?) ask you