Python Projects for Beginners a ten-Week Bootcamp Approach to Python Programming

Handling Function Scope

When dealing with variables declared in a function, you generally won’t need to access it outside of the function. However, in order to access that value, best practice is to return it:

# accessing variables defined in a function def scopeTest( ): word = "function" return word value = scopeTest( ) print(value)

Go ahead and run the cell. Now we have access to the word defined within the function, we simply assign the returned value to another variable to work with.

In-Place Algorithms

When passing variables into a function, you’re simply passing the value of that variable and not the variable itself. Such that the following will not alter the variable num:
>>> num = 5 >>> def changeNum(n):
>>> n += 5
>>> print(num)
This is different when changing information via index though. Due to how index’s work, via memory location and not by reference, changing an element in a list by the index location will alter the original variable. Let’s check out an example:

# changing list item values by index
sports = [ "baseball", "football", "hockey", "basketball" ] def change(aList):
aList[ 0 ] = "soccer" print("Before Altering: { }".format(sports) ) change(sports) print( "After Altering: { }".format(sports) )

Go ahead and run the cell. Notice how the first item in the sports list changes when the function is called. This is due a change in value by the index itself when the list is passed in. These are known as in-place algorithms because no matter where you alter the information, it will change the values in the memory location directly.

THURSDAY EXERCISES

1. Names: Create a function that will change the list passed in with a parameter of name at a given index. Such that if I were to pass in “Bill” and index 1, it would change “Rich” to “Bill.” Use the list and function definition in the following:
>>> names = ['Bob', 'Rich', 'Amanda'] >>> def changeValue(aList, name, index):

Today was important in understanding how variable accessibility works. Knowing this information will keep our variables secure.