Develop Reference

When I import an array from another file, do I take just the data from it or need to "build" the array with how the original file build it?

Sorry if the question is not well formulated, will reformulated if necessary.
I have a file with an array that I filled with data from an online json db, I imported this array to another file to use its data.
#file1
response = urlopen(url1)
a=[]
data = json.loads(response.read())
for i in range(len(data)):
a.append(data[i]['name'])
i+=1
#file2
from file1 import a
'''do something with "a"'''
Does importing the array means I'm filling the array each time I call it in file2?
If that is the case, what can I do to just keep the data from the array without "building" it each time I call it?

If you saved a to a file, then read a -- you will not need to rebuild a -- you can just open it. For example, here's one way to open a text file and get the text from the file:
# set a variable to be the open file
OpenFile = open(file_path, "r")
# set a variable to be everything read from the file, then you can act on that variable
file_guts = OpenFile.read()

From the Python docs on the Modules section - link - you can read:
When you run a Python module with
python fibo.py <arguments>
the code in the module will be executed, just as if you imported it
This means that importing a module has the same behavior as running it as a regular Python script, unless you use the __name__ as mentioned right after this quotation.
Also, if you think about it, you are opening something, reading from it, and then doing some operations. How can you be sure that the content you are now reading from is the same as the one you had read the first time?

Python Script that is changes by execution

how can I write a script that it changes by execution?
For example, two a have script exist from two row:
list = [1, 2, 3, 4, 5]
sliced_list = list[0:1]
Executing it, 2nd row should be:
sliced_list = list[1:2]
and then,
sliced_list = list[2:3]
I want to modify variable "sliced_list" everytime I run this file.

Generally this is not something you should ever want to do, since it is likely to result in non-deterministic behavior, and in the event of a bug its possible to completely overwrite your script and lose data.
If you want to change the date your script is operating on you should store it persistently in some fashion. This could be in a separate file somewhere or in an environment variable.
But to do what your asking you would need to open the script, copy the contents, and modify the content as you desire like this:
with open("/path/to/script.py", 'r+') as script:
contents = script.read()
# ... some string logic here
# Point cursor to the beginning of the file
# If the original contents were longing than the new contents
# you'll have unwanted data at the end of the file.
script.seek(0)
script.write(contents)

You could save the start index into a file when you run the script. Then increment it and save it. Something like what is shown below.
import os
List=[1,2,3,4,5]
file=open('file.txt','r+')
start_index=int(file.read())
print(List[start_index:start_index+1])
file.close()
os.remove('file.txt')
file=open('file.txt','w')
file.write(str(start_index+1))
file.close()

Keep a variable already created after a process is finished in python

I've build a GUI with wxPython in which I use a process to build a table to feed some charts when I click a button.
I build the table and I store it in to a variable to use the information to feed my matplotlib chart.
My problem is that when my chart is finished, based on the already constructed table stored in a variable and the process is finished, I loose the information of that variable and I need to use that same information to make my plot interactive (i.e. to change the plot from line to bar, or stacked or whatever), but the only way I've found is to re run the process to build the table over and over again.
Is there a way to use the stored information of that variable in other processes / modules / charts? I mean, is there a way to keep "active" my variable no matter the process where it was created was finished?
Thanks a lot for your guidance :)

This is done rather easily with the pickle module Here is a simple working example
from pickle import dumps, loads
a_variable = 15 # arbitrary value
with open("a_file.txt", "wb") as fileobj:
# create a pickle string representation of the data
fileobj.write(dumps(a_variable))
# Then to load it from another process
with open("a_file.txt", "rb") as fileobj:
# load the pickle string representation of the data
a_variable = loads(fileobj.read())

How to operate on unsaved Excel file?

I'd like to automate a loop:
ABAQUS generates a Excel file;
Matlab utilises data in Excel file;
loop 1 and 2.
Now my question is: after step 1, the Excel file from ABAQUS is unsaved as Book1. I cannot use Matlab command to save it. Is there a way not to save this ''Book1'' file, but use the data in it? Or if I can find where it is so I can use the data inside? (I assume that Excel always saves the file even though user doesn't?)
Thank you! 

As agentp mentioned, if you are running Abaqus via a Python script, you can just use Python to create a .txt file to save all the relevant information. If well structured, a .txt file can be as readable as an Excel spreadsheet. Because Matlab and Python have intrinsic functions to read and write files this communication can be easily done.
As for Matlab calling Abaqus, you can use something similar to:
system('abaqus cae nogui=YOUR_SCRIPT.py')

Your script that pipes to Excel should have some code similar to this:
abq_ExcelUtilities.excelUtilities.XYtoExcel(
xyDataNames='S:Mises PI: PART-1-1 E: 4309 IP: 1', trueName='')
writing the same data to a report (.rpt) file the code looks like this:
x0 = session.xyDataObjects['S:Mises PI: PART-1-1 E: 4309 IP: 1']
session.writeXYReport(fileName='abaqus.rpt', xyData=(x0, ))
now to "roll your own", use that x0 object: x0.data is a regular python tuple holding the actual data which you can write to a file however you like, eg:
file=open('myfile.csv','w')
for point in x0.data: file.write('%g,%g\n'%point)
file.close()
(you can comment or delete the writeXYReport call )

Storing data globally in Python

Django and Python newbie here. Ok, so I want to make a webpage where the user can enter a number between 1 and 10. Then, I want to display an image corresponding to that number. Each number is associated with an image filename, and these 10 pairs are stored in a list in a .txt file.
One way to retrieve the appropriate filename is to create a NumToImage model, which has an integer field and a string field, and store all 10 NumToImage objects in the SQL database. I could then retrieve the filename for any query number. However, this does not seem like such a great solution for storing a simple .txt file which I know is not going to change.
So, what is the way to do this in Python, without using a database? I am used to C++, where I would create an array of strings, one for each of the numbers, and load these from the .txt file when the application starts. This vector would then lie within a static object such that I can access it from anywhere in my application.
How can a similar thing be done in Python? I don't know how to instantiate a Python object and then enable it to be accessible from other Python scripts. The only way I can think of doing this is to pass the object instance as an argument for every single function that I call, which is just silly.
What's the standard solution to this?
Thank you.

The Python way is quite similar: you run code at the module level, and create objects in the module namespace that can be imported by other modules.
In your case it might look something like this:
myimage.py
imagemap = {}
# Now read the (image_num, image_path) pairs from the
# file one line at a time and do:
# imagemap[image_num] = image_path
views.py
from myimage import imagemap
def my_view(image_num)
image_path = imagemap[image_num]
# do something with image_path