### Question

In the context of this exercise, how does this list comprehension in the example work?

`[t*element + w*n for element in range(d)]`

### Answer

The list comprehension provided in the example code returns a list of x values for the bar locations in the graph.

There are 4 variables which will let us do this:

`n`

determines which dataset it is currently for.

`t`

determines the total number of datasets to graph side by side.

`d`

tells us how many bars there are per dataset.

`w`

tells us the width of each individual bar.

If we take the provided values for the first dataset `China Data`

, we get

`[2*element + 0.8*1 for element in range(7)]`

This essentially means, for each element in `range(7)`

, construct a list where each element is

`2*element + 0.8`

This would give us this list of values,

`[0.8, 2.8, 4.8, 6.8, 8.8, 10.8, 12.8]`

If we change `n`

to 2 for the second dataset `US Data`

, it gives us the list

`[1.6, 3.6, 5.6, 7.6, 9.6, 11.6, 13.6]`

These x values will position each pair of bars for each set of data next to each other in a clear way.