4

I'm printing an array with 100 columns and I would like all columns to have 2 decimals. I would like to use print $0 and not have to individually specify the format for all columns.

OFMT does seen to work with $0:

echo '0.77767686 0.76555555 0.6667667 0.77878878' |awk '{CONVFMT="%.2g";OFMT="%.2g";print ($0+0);print ($0+0)"";print $0}'

Results:

0.78
0.78
0.77767686 0.76555555 0.6667667 0.77878878
Steve
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user1629165
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3 Answers3

10

Note that all input is treated as strings until implicitly converted by how it is used.

OFMT is used when strings are converted to numbers numbers are printed, e.g.:

<<< 0.77767686 awk '{ print 0+$0 }' OFMT='%.2g'

CONVFMT is used when numbers are explicitly converted to strings, e.g.:

<<< 0.77767686 awk '{ print "" 0+$0 }' CONVFMT='%.2g'

Output in both cases:

0.78

The latter converts $0 into a number and then concatenates it with the empty string.

To achieve this for every column I would suggest using a sensible setting of the input and output record separators:

<<< '0.77767686 0.76555555 0.6667667 0.77878878' \
awk '{ print 0+$0 RT }' CONVFMT='%.2g' RS='[ \t\n]+' ORS=''

Note the two conversions, first to a number with 0+$0 then back to a string by concatenating it with RT. RT will be set to the matched record separator. Note that this is GNU awk specific, for a more portable solution, use a loop, e.g.:

<<< '0.77767686 0.76555555 0.6667667 0.77878878' \
awk '{ for (i=1; i<=NF; i++) $i+=0 } 1' CONVFMT='%.2g'

Output in both cases:

0.78 0.77 0.67 0.78

Edit - Responding to @BeeOnRope

@BeeOnRope is correct, OFMT is used as the format specifier when the print-function calls sprintf(), while CONVFMT is used in other conversions. Here is an example that illustrates the difference:

<<< 0.77767686 awk '{ n=0+$1; s=""n; print n, s }' OFMT='%.2g' CONVFMT='%.3g'

Output:

0.78 0.778

Two relevant sections from the GNU awk manual:

Thor
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    That's not correct. Both OMFT and CONVFMT are used for number to string conversions. The difference is that OFMT is used specifically when such a conversion is performed inside a call to print (i.e., print receives a number and needs to format it for output). CONVFMT is used for other conversions that naturally arise e.g. when a string is concatenated to a number and so on. – BeeOnRope Sep 18 '21 at 04:42
  • @BeeOnRope: Thanks I learnt something then. – Thor Sep 20 '21 at 13:18
4

Why don't you use a for loop?

echo '0.77767686 0.76555555 0.6667667 0.77878878' |awk '{ for (i=1; i<=NF; i++) printf "%.2f\n", $i }'

Results:

0.78
0.77
0.67
0.78
Steve
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1

As others have mentioned you need to treat the field as a number to get a conversion. To combine some other ideas you can try:

awk '{ for (i=1; i<=NF; i++) $i += 0; print }'

That will convert every field to a number. You can just convert individual fields with $7 += 0 and so on. You could get fancier by using if (match($i, ...)) with some regexp to select only the numbers you want to convert.

Ben Jackson
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