Writing array a new python file - python-2.7

Question

I have 10 files in a folder. I want to make an array with no of folder and multiply with a variable. As I am new in programming, I am not sure how to perform this. Will it be fine to perform like this,
import numpy as np
folder=/home/foldername/
startfile=[0]
endfile=[9]
x=[0.5]
for i in range(startfile,endfile):
newarray=[i+x]
i+=1
print(newarray)
it is expected to print
newarray=[0.5,1.5,2.5,3.5,4.5,5.5,6.5,7.5,8.5,9.5]

Answer 1

A much simpler way to get the array you want is
>>> newarray = [x + 0.5 for x in range(1, 10)]
>>> newarray
[1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5]
As it stands what you are trying to do instead has several mistakes.
First, range expects integers, but you give it lists:
>>> startfile=[0]
>>> endfile=[9]
>>> for i in range(startfile,endfile):
... print i
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: range() integer end argument expected, got list.
[0] is a list containing 0; just make startfile = 0, and likewise for endfile
>>> startfile=0
>>> endfile=9
>>> for i in range(startfile,endfile):
... print i
...
0
1
2
3
4
5
6
7
8
Notice this go up to but not including 9.
Now, you have i+=1 in your loop, I suspect because you want tomake sure it gets incremented, but the for loop does that for you.
Finally, you have newarray=[i+x], which will reset newarray each time round the loop. If you want to append things to a loop, do just that.
>>> newarray = []
>>> for i in range(startfile,endfile):
... newarray.append(i + 0.5)
...
>>> newarray
[0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5]
Again, note you probably want endfile to be one larger.