change array into table bash scripting - bash

Question

how to change array into tabular form?
eg:
array = 1 2 3 4 5 6 7 8 9 10 11 12
result
1 10 11
2 9 12
3 8
4 7
5 6
in this particular order up-down-down-up-up-down
the array is taken from a .txt file and its based on user input so the value varies
here is some of my code
declare -a myarray
# Load file into array.
readarray myarray < temp2.txt
s=$myarray
f or i in $(seq 0 $((${#s} - 1))); do
echo "s[$i] = \"${s:$i:1}\""
done

Answer 1

This script does what you want:
#!/bin/bash
a=( 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 )
rows=5
for (( j=0; j<rows; ++j )); do
for (( i=0; i<=$(( ${#a[#]} / rows )); ++i )); do
if (( i%2 )); then idx=$(( (i + 1) / 2 * 2 * rows - j - 1 ))
else idx=$(( (i / 2) * 2 * rows + j )); fi
printf "%-4s" "${a[idx]}"
done
printf "\n"
done
Output:
1 10 11
2 9 12
3 8 13 18
4 7 14 17
5 6 15 16
To make it work from left to right rather than from top to bottom, you can simply swap the i and j loops around (and change the name rows to cols so that it still makes sense):
#!/bin/bash
a=( 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 )
cols=5
for (( i=0; i<=$(( ${#a[#]} / cols )); ++i )); do
for (( j=0; j<cols; ++j )); do
if (( i%2 )); then idx=$(( (i + 1) / 2 * 2 * cols - j - 1 ))
else idx=$(( (i / 2) * 2 * cols + j )); fi
printf "%-4s" "${a[idx]}"
done
printf "\n"
done
Output:
1 2 3 4 5
10 9 8 7 6
11 12 13 14 15
18 17 16

Answer 2

declare -a s
s=(1 2 3 4 5 6 7 8 9 10 11 12)
ofstabled=(9 7 5 3 1)
ofstableu=(1 3 5 7 9)
for ((i=0; i<5;++i)); do
for ((j=$i; j<${#s[#]};)); do
printf "%d " ${s[$j]}
let j=$j+${ofstabled[$i]}
if [ $j -lt ${#s[#]} ]; then
printf "%d " ${s[$j]}
let j=$j+${ofstableu[$i]}
fi
done
printf "\n"
done
You can gussy it up if you want but it works.

Answer 3

Script:
#!/bin/bash
a=(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18)
rows=${1:-5}
col=()
for ((i = 0; i < ${#a[#]}; i++)); do
((ind=i % rows))
(( ((i / rows) % 2 == 0) && (ind = ((rows - 1) - ind)) ))
[ -n "${col[(rows - 1) - $ind]}" ] && col[(rows - 1) - $ind]+=" "
col[(rows - 1) - $ind]+=${a[$i]}
done
printf %s\\n "${col[#]}" | column -t
Output:
$ ./order.sh
1 10 11
2 9 12
3 8 13 18
4 7 14 17
5 6 15 16
$ ./order.sh 3
1 6 7 12 13 18
2 5 8 11 14 17
3 4 9 10 15 16
With credit to #TomFenech for the inspiration to make the row count controllable.

Answer 4

You can use awk to read from the file and print it the way you want:
$ awk '{
if(NR<=5) {
a[NR]=$0
next
} else {
row=NR%10
}
}
!(row in a) {
if(row == 0)
row++
else
row=5 - (NR % 5) + 1
}
{
a[row]=a[row] FS $0
}
END {
for(i in a)
print a[i]
}' file
1 10 11
2 9 12
3 8
4 7
5 6