Where does break end the For Loop

Question

I have code that takes in a text file and parses it to get the frequency of each word and store it in a dictionary.

# Load a corpus and build a language model
def load_model(filename):
"""Loads a corpus file and builds a language model consisting of word:frequency.
Converts all words to lowercase, strips punctuation, and ignores any non-alphabetic characters."""

    dictionary = {}
    f = open(filename)
    for line in f:
        words = line.split(' ') # Split each word and iterate through.
        for string in words:

            for c in string: # Check each character value for punctuation or numeric type.

                if c in Punct:
                    string = string.replace(c,"")
                if c.isdigit()
                    print String + ' is not formattable.\n'
                    break

            string = string.lower()
            if string in dictionary:
                dictionary[string] = dictionary[string] + 1
            else:
                dictionary[string] = 1
    f.close()
    return dictionary

My question is I need break to end checking the entire string, not just to end checking a characters.

Does break end the loop it is located in or does it end the first loop: ("for line in f")

And, continue would simply end that particular loop.

I want it so that it ends checking the entire string and it moves on to the next string in words.

Answer 1

From the documentation:

The break statement, like in C, breaks out of the smallest enclosing for or while loop.

According to this question, Python does not support a construct like break 2, as PHP does.

Answer 2

break ends the innermost/immediate loop it is included in, i.e. the one it is directly in the scope of.

for x in X:
    for y in Y:
        break

The x loop will run to completion, the y loop will break.

You can cause a break on the outer loop by maybe setting a variable as a flag:

break_outer = False
for x in X:
    for y in Y:
        if condition:
            break_outer = True
            break
    if break_outer:
        break

Example:

for x in range(3):
    for y in range(2):
        if x == 2:
            break
        print "x =",x,"y =",y

output:

>>> x = 0 y = 0
>>> x = 0 y = 1
>>> x = 2 y = 0
>>> x = 2 y = 1

And to break an outer loop you would pass a variable up:

break_outer = False
for x in range(3):
    for y in range(2):
        if x == 2:
            break_outer = True
            break
        print "x =",x,"y =",y
    if break_outer:
        break

output:

>>> x = 0 y = 0
>>> x = 0 y = 1

continue skips the rest of the code remaining in the loop and continues to the next iteration in the for loop:

for i in range(3):
    if i == 1:
        continue
    print i

output:

>>> 0
>>> 2

Your code seems to do what you are asking though, breaking and moving onto the next word...was there something else about the code that was producing an undesired result?

Answer 3

break will break out of the innermost loop it's in.

You can break out of an outer loop using what @farmerjoe suggested.

But I don't see why you want to do that. The break you have there seems fine as it is: it will stop processing the characters of the current string and move on to checking the next string.

There are some errors in your code. I fixed them for you and some style issues:

def load_model(filename):
    dictionary = {}
    with open(filename) as f:
        for line in f:
            words = line.split(' ')  # Split each word and iterate through.
            for word in words:
                for c in word:  # Check each character value for punctuation or numeric type.
                    if c in Punct:
                        word = word.replace(c, "")
                    if c.isdigit():
                        print word + ' is not formattable.\n'
                        break

                word = word.lower()
                if word in dictionary:
                    dictionary[word] += 1
                else:
                    dictionary[word] = 1
    return dictionary