Create bins with totals and percentage - awk

Question

I would like to create bins to get histogram with totals and percentage, e.g. starting from 0.
If possible to set the minimum and maximum value in the bins ( in my case value min=0 and max=20 )
Input file
8 5
10 1
11 4
12 4
12 4
13 5
16 7
18 9
16 9
17 7
18 5
19 5
20 1
21 7
output desired
0 0 0.0%
0 - 2 0 0.0%
2 - 4 0 0.0%
4 - 6 0 0.0%
6 - 8 0 0.0%
8 - 10 5 6.8%
10 - 12 5 6.8%
12 - 14 13 17.8%
14 - 16 0 0.0%
16 - 18 23 31.5%
18 - 20 19 26.0%
> 20 8 11.0%
---------------------
Total: 73
I use this code from Mr Ed Morton, it works perfectly but the percentage is missed.
awk 'BEGIN { delta = (delta == "" ? 2 : delta) }
{
bucketNr = int(($0+delta) / delta)
cnt[bucketNr]++
numBuckets = (numBuckets > bucketNr ? numBuckets : bucketNr)
}
END {
for (bucketNr=1; bucketNr<=numBuckets; bucketNr++) {
end = beg + delta
printf "%0.1f %0.1f %d\n", beg, end, cnt[bucketNr]
beg = end
}
}' file
Thanks in advance

Answer 1

Your expected output doesn't seem to correspond to your sample input data, but try this variation of that awk code in your question (Intended to be put in an executable file to run as a script, not a a one-liner due to size):
#!/usr/bin/awk -f
BEGIN { delta = (delta == "" ? 2 : delta) }
{
bucketNr = int(($0+delta) / delta)
cnt[bucketNr]++
max[bucketNr] = max[bucketNr] < $2 ? $2 : max[bucketNr]
sum += $2
numBuckets = (numBuckets > bucketNr ? numBuckets : bucketNr)
}
END {
for (bucketNr=1; bucketNr<=numBuckets; bucketNr++) {
end = beg + delta
printf "%d-%d %d %.1f\n", beg, end, max[bucketNr],
(cnt[bucketNr] / NR) * 100
beg = end
}
print "-------------"
print "Total " sum
}
It adds tracking the maximum of the second column for each bin the first column falls in, and prints out a percentage instead of a count of how many rows were in each bin. Plus some tweaks to the output format to better match your desired output.