pl -- Perl One Liners

A perl package useful for perl one liners

alias pl="perl -ML"

If you love pl, welcome to buy me a cup of coffee ☕. Thx!!!

Install

git clone https://github.com/kepbod/pl.git $HOME/pl
cd $HOME/pl
bash install.sh

Document

1 Calculate the sum of a list.

pl -e '@a=(1..5);print sum @a'
# out => 15

2 Calculate the maximum of a list.

pl -e '@a=(1..5);print max @a'
# out => 5

3 Calculate the minimum of a list.

pl -e '@a=(1..5);print min @a'
# out => 1

4 Calculate the percentile of a list.

pl -e '@a=(0..100);print percentile @a,30'
# out => 30

5 Calculate the mean of a list.

pl -e '@a=(1,2,3,3,4,5,6,7,14);print mean @a'
# out => 5

6 Calculate the median of a list.

pl -e '@a=(1,2,3,3,4,5,6,7,14);print median @a'
# out => 4

7 Calculate the Q1 of a list.

pl -e '@a=(0..100);print q1 @a'
# out => 25

8 Calculate the Q3 of a list.

pl -e '@a=(0..100);print q3 @a'
# out => 75

9 Fetch unique entries from a list.

pl -e '@a=(1,2,3,3,4);@b=uniq @a;$,="\t";print @b'
# out => 1 2 3 4

10 Calculate the standard deviation of a list.

pl -e '@a=(1..10);printf("%.3f",sd @a)'
# out => 3.028

11 Calculate the coefficient of variation of a list.

pl -e '@a=(-5,-4,7.5,8.7,3.4,9.4,0.8,1.5,2.6,0.9,0.6,9.4,8.4,6.6,9.4);printf("%.3f", cv @a)'
# out => 1.215

12 Calculate the standard score (Z score) of a list.

pl -e '@a=(-5,-4,-2,-1,-1,0,2,2,3,3,4);@z=zscore @a;printf "%0.3f",$z[0]'
# out => -1.707

13 Calculate the pearson correlation coefficient between two lists.

pl -e '@a=(100,82,89,0);@b=(26,10,5,1);printf "%0.3f", cor(\@a,\@b)'
# out => 0.677

Useful resources for perl one liners

Useful options

• -a: turns on autosplit mode (split command to the @F array) when used with a -n or -p

• -l: enables automatic line-ending processing (1. chomps $/ for each line; 2. assigns $\ after each print)

• -n: reads each line from your file(s) via a loop

• -e: enters one line of program

• -p: reads each line and print $_ from your file(s) via a loop

• -F: specifies the pattern to split on for -a

• -i: processes file(s) in-place

Useful variables

• $_: default input and pattern-searching space
• $": list separator in double-quoted context
• $. or $NR: current line number
• $, or $OFS: output field separator for the print operator
• $/ or $RS: input record separator, newline by default
• $\ or $ORS: output record separator for the print operator
• $ARGV: the name of the current file

Useful blocks

• BEGIN{}: A BEGIN code block is executed as soon as possible, that is, the moment it is completely defined.
• END{}: An END code block is executed as late as possible, that is, after perl has finished running the program and just before the interpreter is being exited.

Quiz of perl oneliner

License

Copyright (C) 2016-2017 Xiao-Ou Zhang. See the LICENSE file for license rights and limitations (MIT).