How to loop my awk script across different columns?

input

name    a1    a2    a3
g1    0.8    0.4    0.2
g2    -0.2    -0.6    -0.7
g3    0.1    0.6    0.8
g4    0.1    0    0
g5    -0.2    -0.2    -0.2
g6    -0.1    -0.9    -0.9
g7    0    0    0.2

output

a1:2
a2:0
a3:0

I use the following

 awk '{if ($2>=0.5) print $1"\t""1"; else if($2<=-0.5) print $1"\t""-1"}'  input |awk '{ sum+=$2} END {print sum}'

2

awk '{if ($3>=0.5) print $1"\t""1"; else if($3<=-0.5) print $1"\t""-1"}'  input |awk '{ sum+=$2} END {print sum}'

0

awk '{if ($4>=0.5) print $1"\t""1"; else if($4<=-0.5) print $1"\t""-1"}'  input |awk '{ sum+=$2} END {print sum}'

0

But I have many columns. Is there anyway I can apply the same command looping over all the columns that gives the above output at once? thanx in advance.

Try something like:

awk '
  NR==1{
    n=split($0,Header)
    next
  }
  {
    for(i=2; i<=NF; i++) {
      if($i>0.5)  Total++
      if($i<-0.5) Total--
    }
  }
  END{
    for(i=2; i<=n; i++)
      print Header ":" Total
  }
' file

Output:

a1:1
a2:-1
a3:-1

You have given incorrect output...
you code is comparing for header column and providing the output as 2, 0, 0.
If you go throug that manually, you will get 1, -1, -1 as output.
Below is the code for that

awk 'NR == 1 {split($0, c, FS); next}
  {if($2 >= 0.5) {v[2] += 1} else if($2 <= -0.5) {v[2] -= 1};
  if($3 >= 0.5) {v[3] += 1} else if($3 <= -0.5) {v[3] -= 1};
  if($4 >= 0.5) {v[4] += 1} else if($4 <= -0.5) {v[4] -= 1}}
  END {for(i = 2; i <= length(c); i++) print c ":" v}' file

yes. you are right. thanx for pointing it out.