Iteration

Strings

Iteration

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Iterating through a string

One of the most useful applications in python are for loops & iterables.

An Iterable refers to a structure of data that the computer can go through one at a time. In a list, each value can be iterated through, and the same holds true for a string. Below is an example of iterating through the string 'Hello World'

            
# Initialize the string String1 = 'Hello World' #Create the for loop for letter in String1: #Print the iterable (letter in this cases) print(letter)

This prints out the following:

            
H e l l o W o r l d

Any time that you iterate through a string, you will be iterating through each one of the characters.

This is very useful if you want to make a letter counter. Lets say that you want to know the count of each letter in a sting. To do this, you would use the following:

            
String1 = 'Hello World' # Initialize the string Letter_counter = {} # Initialize the dictionary to count the letters # Iterate through all the letters for letter in String1: # Conditional if we haven't seen the letter before if letter not in Letter_counter: Letter_counter[letter] = 1 # Conditional if we have already seen the letter before else: Letter_counter[letter] += 1 print(Letter_counter)

This gives back the following dictionary:

{' ': 1, 'H': 1, 'W': 1, 'd': 1, 'e': 1, 'l': 3, 'o': 2, 'r': 1}
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