Maybe I'm missing something, but this doesn't seem too difficult:

> perl -e 'my $x = "0.01 NaN 2.30 4.44";
  my ($d, $e, $f, $g) = ($x =~ /([Na0-9\.\-\0]+\b)/g);
  print "d: $d, e: $e, f: $f, g: $g";'
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output:

d: 0.01, e: NaN, f: 2.30, g: 4.44
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the /g flag makes it return a list of all matches.

I changed \s+ to \b (word-boundary) since the last piece doesn't have a space after it