potential bugs spotted in lesson 2 text

[nigeldgreen]

Hi,

I have just been a helper on this course and noticed a couple of issues that may need amending (detail below). Hope this is OK raised as an issue, very happy to put in as a PR if that is a better way of doing it.

Nigel

Episode 2, about 2/3 of the way down

Text says: "To support this functionality, most array functions allow us to specify the axis we want to work on. If we ask for the average across axis 0 (rows in our 2D example), we get:

print(numpy.mean(data, axis=0))" (table of output follows this)

but if you look at the diagram it shows down arrows for axis=0, and it is clearly showing an average for the days, which are the columns in our data.

Episode 2, Change In Inflammation exercise

This says: "The numpy.diff() function takes an array and returns the differences between two successive values. Let’s use it to examine the changes each day across the first week of patient 3 from our inflammation dataset.", but the first line in the following code is:

patient3_week1 = data[3, :7]

which will give the data for patient 4 (patient 3 is at index 2).

[gcapes]

1. I always find this confusing, but I'm not sure there's a way to make it clearer.
   Row number increases as you go down, so the arrows are correct.
2. I think this means patient_4, so the 5th patient. I think this is fine.