Transpose data in awk - awk

Question

I have a benchmarking tool that has an output looking like this:
Algorithm Data Size CPU Time (ns)
----------------------------------------
bubble_sort 1 16.1
bubble_sort 2 19.1
bubble_sort 4 32.8
bubble_sort 8 74.3
bubble_sort 16 257
bubble_sort 32 997
bubble_sort 64 4225
bubble_sort 128 18925
bubble_sort 256 83565
bubble_sort 512 313589
bubble_sort 1024 1161146
insertion_sort 1 16.1
insertion_sort 2 17.7
insertion_sort 4 26.5
insertion_sort 8 43.7
insertion_sort 16 96.1
insertion_sort 32 263
insertion_sort 64 770
insertion_sort 128 2807
insertion_sort 256 10775
insertion_sort 512 38956
insertion_sort 1024 135419
std_sort 1 17.3
std_sort 2 20.7
std_sort 4 24.4
std_sort 8 32.7
std_sort 16 59.6
std_sort 32 173
std_sort 64 345
std_sort 128 762
std_sort 256 1769
std_sort 512 3982
std_sort 1024 18500
And I'm trying to transform this to become more like this:
Data Size bubble_sort insertion_sort std_sort
1 16.1 16.1 17.3
2 19.1 17.7 20.7
4 32.8 26.5 24.4
8 74.3 43.7 32.7
16 257 96.1 59.6
32 997 263 173
64 4225 770 345
128 18925 2807 762
256 83565 10775 1769
512 313589 38956 3982
1024 1161146 135419 18500
Is there a simple way to achieve this using awk? I'm mostly interested in the numbers in the final table, so the header line isn't essential.
==============================
EDIT:
I was actually able to achieve this using the following code
{
map[$1][$2] = $3
}
END {
for (algo in map) {
some_algo = algo
break;
}
printf "size "
for (algo in map) {
printf "%s ", algo
}
print ""
for (size in map[some_algo]) {
printf "%s ", size
for (algo in map) {
printf "%s ", map[algo][size]
}
printf "\n"
}
}
This works. However, it has two minor problems: It looks a little bit difficult to read, therefore, is there a better and more idiomatic way to do the job? Also, the order of the resulting columns is different from the order in the original data rows. Is there a simple way to fix this order?

Answer 1

here is an alternative
$ sed 1,2d file |
pr -w200 -3t |
awk 'NR==1{print "Data_Size", $1,$4,$7} {print $2,$3,$6,$9}' |
column -t
Data_Size bubble_sort insertion_sort std_sort
1 16.1 16.1 17.3
2 19.1 17.7 20.7
4 32.8 26.5 24.4
8 74.3 43.7 32.7
16 257 96.1 59.6
32 997 263 173
64 4225 770 345
128 18925 2807 762
256 83565 10775 1769
512 313589 38956 3982
1024 1161146 135419 18500

Answer 2

Here is a Ruby to do this.
Ruby is very much like awk but with additional functions and data structures. The advantage to this is it will correctly deal with missing values by inserting n/a if one of the data values is missing.
$ sed 1,2d file |
ruby -lane 'BEGIN{
h=Hash.new {|n,k| n[k]={} }
l="Data_Size"
}
h[l][$F[1]]=$F[1]
h[$F[0]][$F[1]]=$F[2]
END{
puts h.keys.join("\t")
h[l]=h[l].sort{|a,b| a[0].to_i<=>b[0].to_i}.to_h
h[l].each_key { |k|
a=[]
h.each_key { |j|
a.push(h[j][k] || "n/a")
}
puts a.join("\t")
}
}' | column -t
Taking your example and removing the line bubble_sort 4 32.8 prints:
Data_Size bubble_sort insertion_sort std_sort
1 16.1 16.1 17.3
2 19.1 17.7 20.7
4 n/a 26.5 24.4
8 74.3 43.7 32.7
16 257 96.1 59.6
32 997 263 173
64 4225 770 345
128 18925 2807 762
256 83565 10775 1769
512 313589 38956 3982
1024 1161146 135419 18500