Python Clean way to get whether a number is above/below two values and increment accordingly

Question

Consider (simplified)

low_count = 0
high_count = 0
high = 10
low = 5
value = 2

What is a clean way to check a number value versus a min low and a max high, such that if value is below low low_count increments, and if value is above high high_count increments? Currently I have (code snippet)

            high_count = 0
            low_count = 0
            low = spec_df['Lower'][i]
            high = spec_df['Upper'][i]
            #Calculate results above/below limit
            for result in site_results:
                if result<low:
                    low_count+=1
                else:
                    if result>high:
                        high_count+=1

Thanks!

Answer 1

I would write it as

low_count = sum(map(lambda x: x < low, site_results))
high_count = sum(map(lambda x: x > high, site_results))

but admit I'm spoiled by Haskell.

Edit: As suggested by @Nick Burns, using list comprehension will make it even clearer:

low_count = sum(x < low for x in site_results)
high_count = sum(x > high for x in site_results)

Answer 2

You can make use of the fact that Python can interpret boolean values as integers:

for result in site_results:
    low_count  += result < low
    high_count += result > high

If those conditions evaluate to True, this will add 1 to the counts, otherwise 0. This is the same principle as used in the list comprehensions by Bogdan and Nick Burns:

high_count = sum(result > high for result in site_results)

Answer 3

Seems pretty clean. I would edit the following:

elif result>high:
   high_count+=1

Source: http://docs.python.org/2/tutorial/controlflow.html
Is the code not working for you or are you just looking for a better way?

Answer 4

The pythonic way would be:

 for result in site_results:
     if result<low:
        low_count+=1
     elif result>high:
        high_count+=1

Answer 5

For a more complex case, I'd write a function and use a Counter. For example:

def categorize(low, high):
    def func(i):
        if i < low:
            return 'low'
        elif i > high:
            return 'high'
        else:
            return 'middle'
    return func

site_results = list(range(20))

counts = collections.Counter(map(categorize(5, 10), site_results))
print(counts['high'], counts['low'])

But for a trivial case like this, that would be silly. Other than tenstar's/minitech's suggestions, I wouldn't do anything different.