You can avoid the second sort if you use a simple regular array instead of a hash. The idea to sort the lengths and then print the leader is kind of neat, but only keeping the maximum saves memory.
If you want to keep the sort idea, use an array of arrays.
Actually I got a list of file end with *.txt
I want to use the same command apply to all the *.txt
Thus I try to find out the fastest way to write those same command in a script and then want to let them run automatics.
For example:
I got the file below:
file1.txt
file2.txt
file3.txt... (4 Replies)
Hi Experts,
I am adding a column of numbers with awk , however not getting correct output:
# awk '{sum+=$1} END {print sum}' datafile
2.15291e+06
How can I getthe output like : 2152910
Thank you..
# awk '{sum+=$1} END {print sum}' datafile
2.15079e+06 (3 Replies)
Hi
I have many problems with a script. I have a script that formats a text file but always prints the same error when i try to execute it
The code is that:
{
if (NF==17){
print $0
}else{
fields=NF;
all=$0;
while... (2 Replies)
I have two files which I would like to compare and then manipulate in a way.
File1:
pictures.txt 1.1 1.3
dance.txt 1.2 1.4
treehouse.txt 1.3 1.5
File2:
pictures.txt 1.5 ref2313 1.4 ref2345 1.3 ref5432 1.2 ref4244
dance.txt 1.6 ref2342 1.5 ref2352 1.4 ref0695 1.3 ref5738 1.2... (1 Reply)
Hi,
I have a situation to compare one file, say file1.txt with a set of files in directory.The directory contains more than 100 files.
To be more precise, the requirement is to compare the first field of file1.txt with the first field in all the files in the directory.The files in the... (10 Replies)
Hello experts,
I'm stuck with this script for three days now. Here's what i need.
I need to split a large delimited (,) file into 2 files based on the value present in the last field.
Samp: Something.csv
bca,adc,asdf,123,12C
bca,adc,asdf,123,13C
def,adc,asdf,123,12A
I need this split... (6 Replies)
Hi,
I am trying to pass awk field to a command line executed within awk (need to convert a timestamp into formatted date).
All my attempts failed this far.
Here's an example.
It works fine with timestamp hard-codded into the command
echo "1381653229 something" |awk 'BEGIN{cmd="date -d... (4 Replies)
Good evening, Im newbie at unix specially with awk
From an scheduler program called Autosys i want to extract some data reading an inputfile that comprises jobs names, then formating the output to columns for example
1.
This is the inputfile:
$ more MapaRep.txt
ds_extra_nikira_usuarios... (18 Replies)
Discussion started by: alexcol
18 Replies
LEARN ABOUT REDHAT
sort
sort(3pm) Perl Programmers Reference Guide sort(3pm)NAME
sort - perl pragma to control sort() behaviour
SYNOPSIS
use sort 'stable'; # guarantee stability
use sort '_quicksort'; # use a quicksort algorithm
use sort '_mergesort'; # use a mergesort algorithm
use sort 'defaults'; # revert to default behavior
no sort 'stable'; # stability not important
use sort '_qsort'; # alias for quicksort
my $current = sort::current(); # identify prevailing algorithm
DESCRIPTION
With the "sort" pragma you can control the behaviour of the builtin "sort()" function.
In Perl versions 5.6 and earlier the quicksort algorithm was used to implement "sort()", but in Perl 5.8 a mergesort algorithm was also
made available, mainly to guarantee worst case O(N log N) behaviour: the worst case of quicksort is O(N**2). In Perl 5.8 and later, quick-
sort defends against quadratic behaviour by shuffling large arrays before sorting.
A stable sort means that for records that compare equal, the original input ordering is preserved. Mergesort is stable, quicksort is not.
Stability will matter only if elements that compare equal can be distinguished in some other way. That means that simple numerical and
lexical sorts do not profit from stability, since equal elements are indistinguishable. However, with a comparison such as
{ substr($a, 0, 3) cmp substr($b, 0, 3) }
stability might matter because elements that compare equal on the first 3 characters may be distinguished based on subsequent characters.
In Perl 5.8 and later, quicksort can be stabilized, but doing so will add overhead, so it should only be done if it matters.
The best algorithm depends on many things. On average, mergesort does fewer comparisons than quicksort, so it may be better when compli-
cated comparison routines are used. Mergesort also takes advantage of pre-existing order, so it would be favored for using "sort()" to
merge several sorted arrays. On the other hand, quicksort is often faster for small arrays, and on arrays of a few distinct values,
repeated many times. You can force the choice of algorithm with this pragma, but this feels heavy-handed, so the subpragmas beginning with
a "_" may not persist beyond Perl 5.8. The default algorithm is mergesort, which will be stable even if you do not explicitly demand it.
But the stability of the default sort is a side-effect that could change in later versions. If stability is important, be sure to say so
with a
use sort 'stable';
The "no sort" pragma doesn't forbid what follows, it just leaves the choice open. Thus, after
no sort qw(_mergesort stable);
a mergesort, which happens to be stable, will be employed anyway. Note that
no sort "_quicksort";
no sort "_mergesort";
have exactly the same effect, leaving the choice of sort algorithm open.
CAVEATS
This pragma is not lexically scoped: its effect is global to the program it appears in. That means the following will probably not do what
you expect, because both pragmas take effect at compile time, before either "sort()" happens.
{ use sort "_quicksort";
print sort::current . "
";
@a = sort @b;
}
{ use sort "stable";
print sort::current . "
";
@c = sort @d;
}
# prints:
# quicksort stable
# quicksort stable
You can achieve the effect you probably wanted by using "eval()" to defer the pragmas until run time. Use the quoted argument form of
"eval()", not the BLOCK form, as in
eval { use sort "_quicksort" }; # WRONG
or the effect will still be at compile time. Reset to default options before selecting other subpragmas (in case somebody carelessly left
them on) and after sorting, as a courtesy to others.
{ eval 'use sort qw(defaults _quicksort)'; # force quicksort
eval 'no sort "stable"'; # stability not wanted
print sort::current . "
";
@a = sort @b;
eval 'use sort "defaults"'; # clean up, for others
}
{ eval 'use sort qw(defaults stable)'; # force stability
print sort::current . "
";
@c = sort @d;
eval 'use sort "defaults"'; # clean up, for others
}
# prints:
# quicksort
# stable
Scoping for this pragma may change in future versions.
perl v5.8.0 2002-06-01 sort(3pm)