How to convert big numbers into scientific notation

numeric datasedtext formatting

I am working on a file where I have columns of very large values.

(like 40 digits : 646512354651316486246729519751795724672467596754627.06843
and so on …)

I would like to have those numbers in scientific notation but with only 3 or 4 numbers after the dot. Is there a way to use sed or something to do that on every number that appears in my file?

Best Answer

If you want to convert only specific column, awk helps

$ cat ip.txt
foo 64651235465131648624672951975 123
bar 3452356235235235 xyz
baz 234325236452352352345234532 ijkls

$ # change only second column
$ awk '{$2 = sprintf("%.3e", $2)} 1' ip.txt
foo 6.465e+28 123
bar 3.452e+15 xyz
baz 2.343e+26 ijkls

Related Solutions

Print only lines that are completely numeric

awk '
    # skip any obvious stuff
    /[^0-9. -]/ {next}
    {
        # test each field for a number
        for (i=1; i<=NF; i++) 
            if ($i + 0 != $i)
                next
        print
    }
'

This will break for valid numbers in scientific notation: 1.2e1 == 12

Shell – How to write a sed script to delete numbers from a line

Given this input, you want to keep the first and last fields. Pretty simple with awk:

awk '{print $1, $NF}' filename

Using sed, this will replace all space delimited digit-only words:

sed ':a; s/ [[:digit:]]\+ / /; ta'

Best Answer

Related Solutions

Print only lines that are completely numeric

Shell – How to write a sed script to delete numbers from a line

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