Re: [q-lang-users] newbie question on io, etc

[<mip...@ya...>]

 --- s swami <do...@ya...> wrote:
> Lets say I have a file containing 2 columns like
> this:
> 
> john    12
> mary    56
> peter   ab
> vincent 24
> lisa    34
> ...
> etc.
> 
> I would like to read the file and output something
like:
> 
> min score == 12 (John)
> max score == 56 (Mary)
> avg score == 31.5
> 
> Illegal values:
> ab in column 2 on line 3.
> 
> How would I do this in Q? I would especially like to
> see an imperative solution if it exists.

I have one solution.


reviewf Path = review (split "\n" S)
                 where S:String = fget (fopen Path
"r");

// replace 'out of band' values to something
appropriate -- or maybe
// just write a 'firstdata'
review Lines = nextdata (Min,Max,Avg,Bad) Lines 1
                 where Min = (99999,""),
                   Max = (-99999,""),
                   Avg = (0.0,0),
                   Bad = "";

nextdata (Min,Max,Avg,Bad) [] _
  = printf "%s\n%s\n%s\n%s\n" (N,X,V,B)
      where N = sprintf "min score == %d (%s)" Min,
        X = sprintf "max score == %d (%s)" Max,
        V = sprintf "avg score == %.1f (from %d)" Avg,
        B = "\nIllegal values:\n" ++ Bad;
nextdata (Min,Max,Avg,Bad) [L|Ls] Ln = nextdata
(N,X,V,B) Ls (Ln + 1)
                                         where D =
split_data L,
                                           N = nextmin
Min D,
                                           X = nextmax
Max D,
                                           V = nextavg
Avg D,
                                           B = nextbad
Bad D Ln;

nextmin (N1,_) [S2,N2:Int] = (N2,S2) if N1 > N2;
nextmin Min _ = Min;
nextmax (N1,_) [S2,N2:Int] = (N2,S2) if N1 < N2;
nextmax Max _ = Max;
nextavg (V,N) [_,X:Int] = ((V*N+X)/N2,N2) where N2 = N
+ 1;
nextavg Avg _ = Avg otherwise;
nextbad B [_,N:Int] L = B;
nextbad B [S,number N] L = sprintf "%s%s on line %d\n"
(B,N,L);
nextbad B [_,malformed S] L
  = sprintf "%smalformed line on line %d: %s\n"
(B,L,S);

split_data S:String = [Name, number Data]  // 'number'
can fail: see 'nextbad'
                        where [Name, Data] = filter
not_empty (split " \t" S);
split_data S:String = ["", `malformed S];

number S = val S if alldigits S;

alldigits S = true if [true] = regex "" "^[0-9]+$" S
true;
            = false otherwise;

not_empty "" = false;
not_empty X = true;


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