10

I've such a file:

name: xxx --- time: 5.4 seconds
name: yyy --- time: 3.2 seconds
name: zzz --- time: 6.4 seconds
...

Now I want to sort this file by these float numbers to generate a new file as below:

name: yyy --- time: 3.2 seconds
name: xxx --- time: 5.4 seconds
name: zzz --- time: 6.4 seconds
...

I've tried the command awk '{print $5}' myfile | sort -g but this will show me ONLY the float numbers.

1
  • is the problem including values with multiple leading digits and with maybe negative values? there further might be the chance to have exponential notation in large, small and non-needed cases. left alone the fact that a float can be even a "NaN" and its relatives. Nov 12, 2019 at 15:28

1 Answer 1

17

If using GNU sort or compatible, you can use its -g switch to do a general numeric sort:

$ sort -g -k5,5 file
name: yyy --- time: 3.2 seconds
name: xxx --- time: 5.4 seconds
name: zzz --- time: 6.4 seconds

The -k5,5 tells sort to perform the sort on just the 5th column.

Usage

Keep in mind the details from the info sort page:

'-g'
'--general-numeric-sort'
'--sort=general-numeric'
     Sort numerically, converting a prefix of each line to a long
     double-precision floating point number.  *Note Floating point::.
     Do not report overflow, underflow, or conversion errors.  Use the
     following collating sequence:

        * Lines that do not start with numbers (all considered to be
          equal).
        * NaNs ("Not a Number" values, in IEEE floating point
          arithmetic) in a consistent but machine-dependent order.
        * Minus infinity.
        * Finite numbers in ascending numeric order (with -0 and +0
          equal).
        * Plus infinity.

     Use this option only if there is no alternative; it is much slower
     than '--numeric-sort' ('-n') and it can lose information when
     converting to floating point.
4
  • 7
    Note that for numbers like 3.2, standard sort -n would be enough (provided the locale's radix character is that .). You'd need the -g GNU extension for numbers like 1e20, 0x20, inf... Jul 30, 2018 at 6:57
  • 4
    Had to use LC_ALL=C sort -g ... to get my sort to work. Dec 3, 2021 at 14:46
  • @AxelBregnsbo same here, my locale uses a comma as decimal separator, so I had to use LC_NUMERIC=C sort (ALL also works, of course). Thank you for pointing this out.
    – MayeulC
    Mar 15, 2023 at 17:05
  • Apparently this option is incompatible with -u (to remove duplicate lines): with -g, when determining whether two lines are “identical”, only the floating-point number is taken into account!
    – Maëlan
    Nov 4, 2023 at 20:32

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