Section 9.1 Lists
A list is a sequential collection of Python data values, where each value is identified by an index. The values that make up a list are called its elements. Lists are similar to strings, which are ordered collections of characters, except that the elements of a list can have any type and for any one list, the items can be of different types.
Before we examine lists in detail, let’s review what we already know about lists. Take a look at what life would be like without lists. If we wanted to find the average of seven days of maximum temperaturess (in degrees Celsius), we’d need to do something like the following:
temp1 = 22.5
temp2 = 23.1
temp3 = 24.0
temp4 = 22.9
temp5 = 26.1
temp6 = 25.7
temp7 = 27.8
total = temp1 + temp2 + temp3 + temp4 + \
temp5 + temp6 + temp7
avg = total / 7
print(f"Average temperature is {avg:.1f} degrees C.")
Can you imagine what the program would look like if we had a month’s worth of data? Things would get unmanageable very quickly. Luckily, lists help us manage problems like this.
As we saw in
Section 5.6, we can use a
for loop with the accumulator pattern to add up all the items:
