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time trials

The trouble with time

Well…there’s never enough of it, is there?
Let’s look closely at the coach’s data to see what the problem is. Here’s Sarah
raw data again: Oh, look: what a lovely
bunch of strings...

2:58,2.58,2:39,2-25,2-55,2:54,2.18,2:55,2:55
sarah.txt

Recall that data read from a file comes into your program as text, so Sarah’s
data looks like this once you turn it into a list of “times”:

['2:58', '2.58', '2:39’, '2-25', '2-55', '2:54’, '2.18', '2:55', '2:55']

These are all strings, even though the coach
thinks they’re times.

And when you sort Sarah’s data, it ends up in this order (which isn’t quite
what you were expecting): I don’t get what the
problem is...they’re all
times to me.

['2-25', '2-55', '2.18', '2.58', '2:39', '2:54', '2:55', '2:55', '2:58']

Whoops again. 2:39
Whoops! That’s not
right. How can 2.18 can’t come between
come after 2-55? 2.58 and 2:54, can it?

Python sorts the strings, and when it comes to strings, a dash comes before a
period, which itself comes before a colon. As all the strings start with 2, the
next character in each string acts like a grouping mechanism, with the dashed
times grouped and sorted, then the period times, and finally the colon times.

Nonuniformity in the coach’s data is causing the sort to fail.

148 Chapter 5