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}
