Course of Raku / Addendum 🆕 / Bringing it together / Mixed mini-projects / Exercises / Scores from CSV lines

Solution: Scores from CSV lines

Here is a possible solution to the task.

Code

my @lines = 'Anna,90', 'Bob,72', 'Cara,84';
my %score;

for @lines -> $line {
    my ($name, $mark) = $line.split(',');
    %score{$name} = $mark.Int;
}

my $average = ([+] %score.values) / %score.elems;
say "average: $average";

say "above average:";
for %score.sort -> $pair {
    say "  {$pair.key}" if $pair.value > $average;
}

🦋 You can find the source code in the file csv-averages.raku.

Output

average: 82
above average:
  Anna
  Cara

Comments

1. Splitting each line on the comma and assigning to ($name, $mark) unpacks the two fields at once; .Int turns the score text into a number.

2. The average is the sum of the values over their count; anyone whose score beats it is listed. Here the average works out to a whole 82.

3. That final loop can be written as a pipeline. sort orders the pairs, grep keeps the ones above the average, and map reduces each surviving pair to its name — so the loop body carries no logic, only the printing:

   say "  $_" for %score.sort.grep(*.value > $average).map(*.key);

   Reading left to right, this says exactly what it does: sort, keep the ones above average, take their names. Each stage is a small, self-contained step, and *.value / *.key are Whatever stars that build a one-argument block on the fly.

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