Comments on: Star Ratings

By: Tom

Tom — Mon, 23 Apr 2007 16:07:03 +0000

A perfect example of why everyone’s first course in programming should be Fortran.

By: Sam Purtill

Sam Purtill — Sat, 21 Apr 2007 21:48:36 +0000

Hey Leah… Why Django over Ruby on Rails? I picked Django too, and we all have our reasons. Write a post about it!!!

By: leah.culver

leah.culver — Fri, 20 Apr 2007 18:52:36 +0000

Alexander - seems to me like something people would remember if they had used it before. I’d never had to round like that before and I kept thinking that there was some way to do it mathematically, but I couldn’t remember how. I hope it’s not as important to know the best solution as it is to know a better solution exists.

Richard and Christopher - I suppose I was being too generous with .7. I don’t mind the rounding difference and I doubt the cheeseburgers will either.

Everybody - Thanks so much for the help! I suppose I could have looked around more for the solution but now I feel like my blog was actually useful.

By: Richard Kiss

Richard Kiss — Fri, 20 Apr 2007 18:11:36 +0000

Here’s an idea:

stars = float(str(round(float(star_sum)/num_raters,1)).split(’.')[0]) + {’0′:0, ‘1′:0, ‘2′:0, ‘3′:0.5, ‘4′:0.5, ‘5′:0.5, ‘6′:0.5, ‘7′:0.5, ‘8′:1.0,’9′:1.0}[str(round(float(star_sum)/num_raters,1)).split(’.')[1]]

or more concisely,

stars = round(float(star_sum+star_sum)/num_raters)/2

By: Alexander Repty

Alexander Repty — Fri, 20 Apr 2007 08:13:35 +0000

I gave this to some of my co-workers (system administrators and software developers) as a challenge. Only 2 out of 7 could get it right (both software developers - one of them an apprentice).

I immediately knew the solution when I finished reading the problem at hand, and I would have done it exactly like Bob did. I guess it’s just the experience in solving problems like this one that enables you to see this solution.

By: Bob Ippolito

Bob Ippolito — Fri, 20 Apr 2007 02:02:07 +0000

In general you should never have to convert a number to a string. If you needed to get the fractional and whole parts of a float there’s math.modf(someFloat) which returns (frac, whole). Anyway, I would probably just double the sum, round, then half it.

stars = 0.5 * round((2.0 * star_sum) / num_raters)

By: J Taylor

J Taylor — Fri, 20 Apr 2007 01:55:25 +0000

#I don’t program in Python and I’m not sure if this code has the correct syntax
#Calculate rating out of 10
rating = round(star_sum*2/num_raters, 1)
#Calculate number of whole stars by integer division
whole_stars = rating // 2
#Calculate number of half stars by remainder
half_stars = rating % 2
#Combine into one number
stars = whole_stars + (half_stars * 0.5)

By: Christopher Finke

Christopher Finke — Thu, 19 Apr 2007 22:58:08 +0000

If you’re willing to change your boundaries to .75 and .25 (rather than .7 and .3), you could do this:

stars = float(round(star_sum / num_raters * 2) / 2);

By: r

Thu, 19 Apr 2007 22:11:19 +0000

might be misunderstanding what you’re trying to do, but

formatting an average value to the nearest half (forgive the lack of python syntax):

round(AvgValue * 2) / 2

should work