Chris Angelico <ros...@gmail.com> writes:
> On Tue, Aug 10, 2021 at 7:25 AM Hope Rouselle <hrouselle@jevedi.xotimo> wrote:
>> I came up with the following question. Using strings of length 5
>> (always), write a procedure histogram(s) that consumes a string and
>> produces a dictionary whose keys are each substrings (of the string) of
>> length 1 and their corresponding values are the number of times each
>> such substrings appear. For example, histogram("aaaaa") = {"a": 5}.
>> Students can "loop through" the string by writing out s[0], s[1], s[2],
>> s[3], s[4].
>
> In other words, recreate collections.Counter? Seems decent, but you'll
> need to decide whether you want them to use defaultdict, use
> __missing__, or do it all manually.
Yes, the course introduces very little so there is a lot of recreation
going on. Hm, I don't know defaultdict and I don't know how to use
__missing__. The course does introduce dict.get(), though. If students
use dict.get(), then the procedure could essentially be:
def histogram(s):
d = {}
d[s[0]] = d.get(s[0], 0) + 1
d[s[1]] = d.get(s[1], 0) + 1
d[s[2]] = d.get(s[2], 0) + 1
d[s[3]] = d.get(s[3], 0) + 1
d[s[4]] = d.get(s[4], 0) + 1
return d
>> I think you get the idea. I hope you can provide me with creativity. I
>> have been looking at books, but every one I look at they introduce loops
>> very quickly and off they go. Thank you!
>
> Probably because loops are kinda important? :)
Totally important. But each course author thinks they know better.
Sometimes a college professor can do very little to help her students.
I am actually fond of functional programming as a first course using a
language with as little syntax as possible. Python is very nice but
it's not a small language. It's easy to see courses spending an entire
semester on introducing syntax and this one is no different. I think
it's more interesting to see all the syntax in a few minutes and spend
the semester on strategies.
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