[Basic Grammar] Python Arrays

• Array 

3

An array is a special variable, which can hold more than one value at a time. 

 

• Access the elements of an array 

Refer to the index number. 

 

Example 

colors = ["white", "blue", "red"]

x = colors[0]
print (x)

white

 

Change the value of third array item.

colors = ["white", "blue", "red"]

colors[2] = "black"
print (colors)

['white', 'blue', 'black']

 

• The length of an array 

Use len () to get a result of length of an array.

 

Example 

cars = ["Ford", "Volvo", "BMW"]

x = len(cars)

print(x)

3

 

• Looping Array Elements 

You can use the for in loop to loop through all the elements of an array. 

 

Example 

colors = ["white", "blue", "red"]
for x in colors: 
	print (x)

 

• Adding Array Elements 

Use append() to add an element to an array. 

 

Example 

colors.append ("purple")

 

• Removing Array Elements 

There are two different ways you can remove the elements in an array. 

 

• pop()

Example 

Remove the second element in the array.

colors.pop(1)

 

• remove()

Example 

Remove the value white. 

colors.remove("white")

 

Exercises 

1. Create a Python program that takes a list of names and counts how many names in the list start with the letter "A."

names = ["Alice", "Bob", "Charlie", "David", "Anna", "Eva"]

count_a_name = len ([name for name in names if name.startswith("A")])
print ("Number of names starting with 'A':", count_a_names)

Number of names starting with 'A': 2

2. Get the value of the first array item.

names = ["Alice", "Bob", "Charlie", "David", "Anna", "Eva"]

x = names[0]
print(x)

Alice