[Python] For/while loops on lists

[NoteMe]

I forgot bringing my book with me at work today...grrr...


But here is what I need to do. I have 2 lists. One list has been made by reading in line by line a file. Then I have an other lists with words like this:

[code]
link_types = ["acro",
"also",
"award",
....
"stat".
"trans",
"who",][/list]

And I need to go through every line that doesn't start with a " " and check if one of those words are on the differnt lines. And it has to be fast.

So I was guessing something like this would work:

print "\nChecking the link types:"
line_number
for line in lines:
    if line[0] == " ":
        found_it = 0
        for types in link_types:
            if types in line:
                found_it = 1

        if found_it == 0:
            print line

But here it checks for every word in the list, even if it has all ready found it. If would be much faster if the inner loop was a while loop. But how would I know when it came to the end of the link_types list?

So what I want is something like this:

print "\nChecking the link types:"
line_number = 0
for line in lines:
    line_number = line_number + 1
    if line[0] == " ":
        found_it = 0
        while types in link_types and found_it != 0:
            if types in line:
                found_it = 1

        if found_it == 0:
            print "\nLine: " + line_number + line

But I am getting an error on the "while" line. Can't I use while on a list?

[dglienna]

This may help if you haven't seen it yet...

http://www.python.org/

this is there, too

while_stmt      ::=     "while" expression ":" suite
        ["else" ":" suite]

[NoteMe]

Well, yeah that is the syntax of a normal while loop, but it has nothing to do with traversing a list. So it is kind of unusefull.

I am starting to think that it is not possible to traverse through a list using a while loop....


ØØ

[VBD]

for line in lines:
    line_number = line_number + 1
    if line[0] == " ":
        found_it = 0
        cindex = 0
        while cindex < len(linked_types) and found_it != 0:
            if linked_types[cindex] in line:
                found_it = 1
            cindex=cindex+1

A while loop is not designed to iterate through a list, while a for loop is. This is because a while loop is designed to continue going until certain conditions are met. Thus, you must do things manually. You could also do:

for line in lines:
    line_number = line_number + 1
    if line[0] == " ":
        found_it = 0
        cindex = 0
        lt2=linked_types[:]
        while len(lt2) and found_it != 0:
            types=lt2.pop()
            if types in line:
                found_it = 1
            cindex=cindex+1

Still, the best way of all is:

print "\nChecking the link types:"
line_number
for line in lines:
    if line[0] == " ":
        found_it = 0
        for types in link_types:
            if types in line:
                found_it = 1
                break
        if found_it == 0:
            print line

When iterating through a list, use a For loop. Its designed for it. Just use the break statement to break out of it when you so desire.

[NoteMe]

Well, the break is what I am using at the moment. But it looks ugly, at least in 2 nested for loops, then you have to have 2 break, and an if to test if it breaked on the inner one, something like:

for files_comp in files_and_lines:
     for line_comp in files_comp:
         if line_comp == line:
              found = 1
              break

     if found == 1:
          break


if found == 0:
     print "Line: " + line_number
     print line

And you are saying that while loops are designed to go on to a condition is met. I know that of course, but I was hoping there was a condition like EOF (End of file) or something for list, since it was so easy to iterate the list with a for loop, but so ugly when you have to use breaks.


But since it doesn't look like that is possible, then I guess I just have to use breaks for list. Grrr....well thanks for the answer.


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