List comprehensions in Python can be tricky and hard to look at but once you know the secret, it will become very clear, for example, say we have a list:

a = [1, 2, 3, 4, 5]

And we want to make a second list out of this “b” with values of “a” plus 2, so we want to get this:

b = [3, 4, 5, 6, 7]

Now, the way to do this without using any fancy feature would be:

b = []
for item in a:
    b.append(item + 2)

To turn this into a list comprehension we will start like this:

b = [for item in a]

Now, we will have to add our “item + 2″ to the left side of the for loop so:

b = [item + 2 for item in a]

If you didn’t understand what happened, don’t worry, just keep reading.
Now, let’s look at another example, this time, we will try to understand a list comprehension that’s already written, a very simple one:

a = [1, 2, 3, 4, 5]
b = [x*x*x for x in a]

To read this, start form right to left:

for x in a: x*x*x

Internally, this will be translated to something like:

b = []
for x in a:
    b.append(x*x*x)

So the secret is to read from right to left.

If there should be a condition, it will come after the for loop so to increment all the items that are greater than 4 by 2:

b = [item + 2 for item in a if item > 4]

I hope this helps

Here is another little trick in Python; the print statement always inserts a line break after it prints your text, for example:

print "Hello"
print "Python"
print "!"

Will print:
Hello
Python
!

Now, you can fix the issue with the line break by inserting a comma after the print statement:

print "Hello",
print "Python",
print "!"

This will print:
Hello Python !

But the problem is that it will still insert a space after it prints the text, so to fix this you will have to use sys.stdout.write like this:

import sys
sys.stdout.write("Hello ")
sys.stdout.write("Python")
sys.stdout.write("!")

This will print:
Hello Python!

Have fun with Python

Update:
There is __file__ in Python.

You could do this as suggested by some but I don’t know why:

import inspect
this_file = inspect.currentframe().f_code.co_filename

I hope this helps