Module 6: Loops and For Loops
Notes of for loop
-For loop must always start with the for keyword -The for statement must end with a colon (:) -The entirety of the nested block of code within the for statement must be indented
Iteration
each cycle through the loop Ex: i=1 while i < 20 print(i) i=i+2
Using for loops with the range() function
-Can also use for loops to iterate through a sequence of numbers. -Use the range() function to generate the sequence of numbers
Using for loops with strings
-Also use a for loop to iterate through the items in a string -Strings are simply a sequence of individual character
Notes on the range function
-Start specifies the starting number in the sequence. It is optional. If it is not specified, 0 is used -Stop specifies the stopping number in the sequence. It is exclusive. The number is not included in the sequence -Step specifies how big of a hop to make when generating numbers for the sequence. It is also optional. If it is not specified 1 is used
Comprehensions
Allow us to create lists tuples and dictionaries in a concise manner. Comprehensions make our code more concise, but the syntax may take some time to get used to
Using the continue keyword
Allows us to skip the current iteration and move on to the next.
Loop
Block of code that repeats until a specified condition is reached
Using for loops with lists
Common uses of a for loop is to iterate through the items in a list We can do this manually with indexed print statements but we can achieve this with just one print statement with for loop
for key in fruit_price.keys(): print(key.capitalize())
Iterate through all the keys in dictionaries
for value in fruit_price.values(): discount_value = round(value * 0.8, 2) print(discount_value)
Iterate through all values for dictionaries
Range function
Special type of python object designed to work with loops Ex: range(1,20,2)
Using the break keyword
While iterating through a for loop we sometimes need to exit the loop early. We can use the break keyword to terminate the loop before it runs its course
Sequence
any object that is made up of a collection of other objects (strings, lists, dictionaries, arrays)
for loop syntax
for <var> in <container>: <code>
<var>
is a variable name that represents each element in a container
<code>
is the block of code that executes for each iteration through the container
<container>
is the container or sequence we iterate through
range(start, stop, step)
syntax for range function
For loop
used to iterate over the item of a sequence or container By iterating through sequences for loops allow us to repeat tasks a finite number of times