Learning lists - all operations

#!/usr/local/bin/python2.7

'''
    File name: list_all_operations.py
    Author: Prabhath Kota
    Date: June 22, 2018
    Python Version: 2.7
'''

freedom_fighters = ["Lala Lajipati Rai", "Dadabhai Naoroji", "Rajendra Prasad", "Sarojini Naidu", "Dadabhai Naoroji", "Lal Bahadur Shastri"]
print freedom_fighters
#['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Rajendra Prasad', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']

print '---------------index---------------'
print freedom_fighters[0]
print freedom_fighters[-1]
print freedom_fighters[2:]
print freedom_fighters[:-1]
print freedom_fighters[2:4]

#Lala Lajipati Rai
#Lal Bahadur Shastri
#['Rajendra Prasad', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']
#['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Rajendra Prasad', 'Sarojini Naidu', 'Dadabhai Naoroji']
#['Rajendra Prasad', 'Sarojini Naidu']

print '---------------insert in index---------------'
freedom_fighters[2] = 'Subhash Chandra Bose'
print freedom_fighters
#['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Subhash Chandra Bose', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']

print '---------------Add Element append vs extend---------------'
print freedom_fighters
#Append - appends as a single item
freedom_fighters.append('Subhash Chandra Bose')
print freedom_fighters
freedom_fighters.pop()
freedom_fighters.append(['Subhash Chandra Bose', 'Lal Bahadur Shastri'])
print freedom_fighters
freedom_fighters.pop()
#Extend - it adds multiple values
freedom_fighters.extend(['Subhash Chandra Bose', 'Lal Bahadur Shastri'])
print freedom_fighters
freedom_fighters.pop()
freedom_fighters.pop()
print freedom_fighters

#['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Subhash Chandra Bose', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']
#['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Subhash Chandra Bose', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri', 'Subhash Chandra Bose', ['Subhash Chandra Bose', 'Lal Bahadur Shastri']]
#['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Subhash Chandra Bose', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri', 'Subhash Chandra Bose', 'Subhash Chandra Bose', 'Lal Bahadur Shastri']
#['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Subhash Chandra Bose', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']

print '---------------Remove Element by value---------------'
print freedom_fighters
freedom_fighters.remove('Subhash Chandra Bose')
print freedom_fighters

#['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Subhash Chandra Bose', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']
#['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']

print '-----------delete by index---------------------'
print freedom_fighters
del freedom_fighters[-1] #removes index element
del freedom_fighters[1] #removes index element
print freedom_fighters

#['Lala Lajipati Rai', 'Dadabhai Naoroji', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Lal Bahadur Shastri']
#['Lala Lajipati Rai', 'Sarojini Naidu', 'Dadabhai Naoroji']

print '---------------By Ref---------------'
print freedom_fighters

#copy by Reference
freedom_fighters_1 = freedom_fighters
freedom_fighters_1.append('Bhagat Singh')
print freedom_fighters
print freedom_fighters_1

#['Lala Lajipati Rai', 'Sarojini Naidu', 'Dadabhai Naoroji']
#['Lala Lajipati Rai', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Bhagat Singh']
#['Lala Lajipati Rai', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Bhagat Singh']

print '---------------By Value -----------'
#copy by value
freedom_fighters_2 = freedom_fighters[:]
freedom_fighters_2.append('Sardar Vallabhbhai Patel')
print freedom_fighters
print freedom_fighters_2

#['Lala Lajipati Rai', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Bhagat Singh']
#['Lala Lajipati Rai', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Bhagat Singh', 'Sardar Vallabhbhai Patel']

print '---------------List Comprehension ---------------'

#This gives list
print [i + ' - India Salutes you' for i in freedom_fighters]

#tuple - gives generator object
generator_obj = (i + ' - India Salutes you' for i in freedom_fighters)
print generator_obj
for each in generator_obj:
print each

#['Lala Lajipati Rai - India Salutes you', 'Sarojini Naidu - India Salutes you', 'Dadabhai Naoroji - India Salutes you', 'Bhagat Singh - India Salutes you']
#<generator object <genexpr> at 0x0000000001EB41B0>
#Lala Lajipati Rai - India Salutes you
#Sarojini Naidu - India Salutes you
#Dadabhai Naoroji - India Salutes you
#Bhagat Singh - India Salutes you

print '---------------Sorted()---------------'
print freedom_fighters
print sorted(freedom_fighters)
print freedom_fighters

#['Lala Lajipati Rai', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Bhagat Singh']
#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu']
#['Lala Lajipati Rai', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Bhagat Singh']

print '---------------list.reverse() ---------------'
print freedom_fighters
print freedom_fighters.reverse() #Returns None but reverse itself
print freedom_fighters

#['Lala Lajipati Rai', 'Sarojini Naidu', 'Dadabhai Naoroji', 'Bhagat Singh']
#None
#['Bhagat Singh', 'Dadabhai Naoroji', 'Sarojini Naidu', 'Lala Lajipati Rai']

print '---------------list.sort() ---------------'
print freedom_fighters
print freedom_fighters.sort() #Returns None but sorts itself
print freedom_fighters

#['Bhagat Singh', 'Dadabhai Naoroji', 'Sarojini Naidu', 'Lala Lajipati Rai']
#None
#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu']

print '---------------multiply---------------'
freedom_fighters2 = freedom_fighters * 2
print freedom_fighters2
#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu']

print '---------------check if item exits---------------'
print freedom_fighters
print 'Bhagat Singh' in freedom_fighters
print 'Sardar Vallabhbhai Patel' in freedom_fighters

#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu']
#True
#False

print '---------------Remove Duplicates---------------'
print freedom_fighters
freedom_fighters.append('Mahatma Gandhi')
freedom_fighters.append('Mahatma Gandhi')
print freedom_fighters
freedom_fighters_no_dup = []
[freedom_fighters_no_dup.append(x) for x in freedom_fighters if x not in freedom_fighters_no_dup]
print freedom_fighters_no_dup
print list(set(freedom_fighters)) #set - unordered collection data type, this kills the original order

#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu']
#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi']
#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi']
#['Mahatma Gandhi', 'Bhagat Singh', 'Lala Lajipati Rai', 'Dadabhai Naoroji', 'Sarojini Naidu']

print '---------------Convert to tuple---------------'
print freedom_fighters
print tuple(freedom_fighters)
print list(tuple(freedom_fighters))

#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi']
#('Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi')
#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi']

print '---------------length of array---------------'
print freedom_fighters
print len(freedom_fighters) 

#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi']
#6

print '---------------Find count of Element---------------'
freedom_fighters.append('Bhagat Singh')
print freedom_fighters
print freedom_fighters.count('Bhagat Singh')

#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi', 'Bhagat Singh']
#2

print '---------------Pop---------------'
#pop() method removes and returns the last item if index is not provided
print freedom_fighters
freedom_fighters.pop()
print freedom_fighters

#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi', 'Bhagat Singh']
#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi']

print '---------------Insert---------------'
#When you insert(-3, 0) you are inserting 0 before index -3. 
#When it says "before" it has nothing to do with the direction of travel.
print freedom_fighters
freedom_fighters.insert(0,'Sarojini Naidu')
freedom_fighters.insert(len(freedom_fighters),'Sarojini Naidu')
print freedom_fighters
freedom_fighters.insert(-1,'Bhagat Singh')
print freedom_fighters
del freedom_fighters[0]
freedom_fighters.pop()
freedom_fighters.pop()
print freedom_fighters

#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi']
#['Sarojini Naidu', 'Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi', 'Sarojini Naidu']
#['Sarojini Naidu', 'Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi', 'Bhagat Singh', 'Sarojini Naidu']
#['Bhagat Singh', 'Dadabhai Naoroji', 'Lala Lajipati Rai', 'Sarojini Naidu', 'Mahatma Gandhi', 'Mahatma Gandhi']

print '---------------Other Functions---------------'
#sorted(freedom_fighters)
#print max(freedom_fighters)
#print min(freedom_fighters)
#print sum(list1)

How to remove duplicate lines from a file in perl

Today, we discuss about the following :
1) How to open the directory & read all the files
2) In each file, remove duplicate lines from a file and keep it in same path/file or different path/file
4) How to create time-stamp in Perl
3) How to create a log file and log the changes

Mention the corresponding path where you want to copy

e.g., If you want to remove duplicated line and copy in the same file
my $input_dir  = "/nfs/fm/disks/my_files";
my $output_dir = "/nfs/fm/disks/my_files";
my $log_dir    = "/nfs/fm/disks/my_files";

e.g., If you want to copy the output of the files in different locations
my $input_dir  = "/nfs/fm/disks/input_dir";
my $output_dir = "/nfs/fm/disks/output_dir";
my $log_dir    = "/nfs/fm/disks/log_fir";

remove_duplicates.pl

#!/usr/bin/perl

use strict;
use warnings;

my $input_dir  = "/nfs/fm/disks/my_files";
my $output_dir = "/nfs/fm/disks/my_files"; 
my $log_dir    = "/nfs/fm/disks/my_files";

my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst);

($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);
$sec  = sprintf("%02d",$sec);
$min  = sprintf("%02d",$min);
$hour = sprintf("%02d",$hour);
$mday = sprintf("%02d", $mday);
$mon  = sprintf("%02d", $mon+1);
$year = sprintf("%04d", $year+1900);

my $output_tag = $mday .'_'. $mon .'_'. $year .'_'. $hour .'_'. $min;

opendir(IN_DIR, $input_dir) or die $!; 
opendir(OUT_DIR, $output_dir) or die $!; 
opendir(LOG_DIR, $log_dir) or die $!; 

open (LOG_FILE, "> $log_dir/remove_duplicate_lines.log");

print LOG_FILE "------------- START ------------ \n";

my (@invalid_list_files, %file_without_dup );

while (my $file = readdir(IN_DIR)) {

    next if $file =~ /^\./;

    print LOG_FILE "\n Folder Path : " , "$input_dir/$file";    

    unless (-f "$input_dir/$file") {
        print LOG_FILE "\n Not a File : " . $file;
        next;
    }
        
    print LOG_FILE "\n File Name : " . $file  . "\n";

    #Reading the File 
    open(IN_FILE, "<$file") ||  die "\n Cant open file for reading: " . $file;
    my @lines = 
    close(IN_FILE);

    my @newlines;
    foreach my $each_line (@lines) {
        if (not defined $file_without_dup{$each_line}) {
            push(@newlines, $each_line);
        }
        $file_without_dup{$each_line} = 1;
    }

    #Writing into Output Files
    open(OUT_FILE, ">$output_dir/$file") || die "-W- Cant open file for writing: " . "$output_dir/$file";
    print OUT_FILE @newlines;
    close(OUT_FILE);
    
}
close (LOG_FILE);
closedir(IN_DIR);
closedir(OUT_DIR);
closedir(LOG_DIR);

1;

You may also wish to read Object Oriented Concepts in Python as mentioned :
Python Class and Object Example
Inheritance in Python
Packages in Python
Exceptions in Python

Different ways to remove duplicates from array

#!F:\Perl\bin\perl -w
use strict;
use Data::Dumper;

#Remove duplicates from array.
my @array = qw/10 20 20 20 30 40 40 40 50 50 50/;
print "\n Duplicate array: @array";

1) Good

my %hash;
$hash{$_} = 0 for (@array);
# $hash{$_} = () for (@array); #You can do this also

my @final = keys (%hash);
print "\n Unique Array: @final";
print "\n";


2) Best of all

my %hash = map { $_ , 1 } @array;
my @uniq = keys %hash;
print "\n Uniq Array:", Dumper(\@uniq);


3) Costly process as it involves 'greping'

my %saw;
my @out = grep(!$saw{$_}++, @array);
print "\n Uniq Array: @out \n";