"S Potter" <[EMAIL PROTECTED]> wrote
How do I filter my first list based upon the selected position
or a variable equal to the value of the selected position from
my second list?
The most common way of filtering a list is to use a list comprehension
filteredList = [item <for expression> if <filter expression> ]
where <filter expression> can be any expression or function that you
can write.
and <for expression> is like a normal for loop construct.
So if you write a function that compares an item from the original
list
with the items in your control list you can get what you want
eg
L = [5,6,7,8,9]
[n for i,n in enumerate(L) if i % 2] # equivalent to getting all
odd indexed items
[6, 8]
There is also the older filter() function which some people prefer.
You will find examples of both in the Functional Programming topic
of my tutor.
Question 2.) If I assign a value to a variable x = "MyVlaue"
How do I put the value of x into a list?
You can use append or insert or use slicing to replace a series of
values
with a new value.
x = 42
myList = [x] # new list containing x
myList.append(66) # add 66 to the list -> [42,66]
myList.insert(1,7) # insert 7 at index 1 -> [42,7,66]
I would think it would be something like:
list[(str(x))]
That would convert x to a string and then try to use it to
index a list called list (which is a bad name because it would
hide the function for converting things to a list!)
Which tutorial are you using to learn? Most tutorials will cover this
sort of stuff. Look in the Raw Materials topic of my tutor for more
info on using lists.
This would probably be considered macro-substitution in other
languages but I cannot find reference to this in python.
There is no real concept of macro substitution in Python and frankly
I don't see what you describe as being much like what I understand
macro substitution to be in languages like C, Assembler or Lisp...
--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld
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