I am trying to parse a CSV file to read in all the other zip codes. I am trying to create a hash where each key is a zip code and the value is the number it appears in the file. Then I want to print out the contents as Zip Code - Number. Here is the Perl script I have so far.
use strict;
use warnings;
my %hash = qw (
zipcode count
);
my $file = $ARGV[0] or die "Need CSV file on command line \n";
open(my $data, '<', $file) or die "Could not open '$file $!\n";
while (my $line = <$data>) {
chomp $line;
my #fields = split "," , $line;
if (exists($hash{$fields[2]})) {
$hash{$fields[1]}++;
}else {
$hash{$fields[1]} = 1;
}
}
my $key;
my $value;
while (($key, $value) = each(%hash)) {
print "$key - $value\n";
}
exit;
You don't say which column your zip code is in, but you are using the third field to check for an existing hash element, and then the second field to increment it.
There is no need to check whether a hash element already exists: Perl will happily create a non-existent hash element and increment it to 1 the first time you access it.
There is also no need to explicitly open any files passed as command line parameters: Perl will open them and read them if you use the <> operator without a file handle.
This reworking of your own program may work. It assumes the zip code is in the second column of the CSV. If it is anywhere else just change ++$hash{$fields[1]} appropriately.
use strict;
use warnings;
#ARGV or die "Need CSV file on command line \n";
my %counts;
while (my $line = <>) {
chomp $line;
my #fields = split /,/, $line;
++$counts{$fields[1]};
}
while (my ($key, $value) = each %counts) {
print "$key - $value\n";
}
Sorry if this is off-topic, but if you're on a system with the standard Unix text processing tools, you could use this command to count the number of occurrences of each value in field #2, and not need to write any code.
cut -d, -f2 filename.csv | sort | uniq -c
which will generate something like this output, where the count is listed first, and the zipcode second:
12 12345
2 56789
34 78912
1 90210
Related
I have a simple text file that includes all 50 states. I want the user to enter a word and have the program return the line the specific state is on in the file or otherwise display a "word not found" message. I do not know how to use find. Can someone assist with this? This is what I have so far.
#!/bin/perl -w
open(FILENAME,"<WordList.txt"); #opens WordList.txt
my(#list) = <FILENAME>; #read file into list
my($state); #create private "state" variable
print "Enter a US state to search for: \n"; #Print statement
$line = <STDIN>; #use of STDIN to read input from user
close (FILENAME);
An alternative solution that reads only the parts of the file until a result is found, or the file is exhausted:
use strict;
use warnings;
print "Enter a US state to search for: \n";
my $line = <STDIN>;
chomp($line);
# open file with 3 argument open (safer)
open my $fh, '<', 'WordList.txt'
or die "Unable to open 'WordList.txt' for reading: $!";
# read the file until result is found or the file is exhausted
my $found = 0;
while ( my $row = <$fh> ) {
chomp($row);
next unless $row eq $line;
# $. is a special variable representing the line number
# of the currently(most recently) accessed filehandle
print "Found '$line' on line# $.\n";
$found = 1; # indicate that you found a result
last; # stop searching
}
close($fh);
unless ( $found ) {
print "'$line' was not found\n";
}
General notes:
always use strict; and use warnings; they will save you from a wide range of bugs
3 argument open is generally preferred, as well as the or die ... statement. If you are unable to open the file, reading from the filehandle will fail
$. documentation can be found in perldoc perlvar
Tool for the job is grep.
chomp ( $line ); #remove linefeeds
print "$line is in list\n" if grep { m/^\Q$line\E$/g } #list;
You could also transform your #list into a hash, and test that, using map:
my %cities = map { $_ => 1 } #list;
if ( $cities{$line} ) { print "$line is in list\n";}
Note - the above, because of the presence of ^ and $ is an exact match (and case sensitive). You can easily adjust it to support fuzzier scenarios.
I am attempting to read a CSV into an array in a way that I can access each column in a row. However when I run the following code with the goal of printing a specific column from each row, it only outputs empty lines.
#set command line arguments
my ($infi, $outdir, $idcol) = #ARGV;
#lead file of data to get annotations for
open FILE, "<", $infi or die "Can't read file '$infi' [$!]\n";
my #data;
foreach my $row (<FILE>){
chomp $row;
my #cells = split /\t/, $row;
push #data, #cells;
}
#fetch genes
foreach (#data){
print "#_[$idcol]\n";
# print $geneadaptor->fetch_by_dbID($_[$idcol]);
}
With a test input of
a b c
1 2 3
d e f
4 5 6
I think the issue here isn't so much loading the file, but in treating the resulting array. How should I be approaching this problem?
First of all you need to push #data, \#cells, otherwise you will get all the fields concatenated into a single list.
Then you need to use the loop value in the second for loop.
foreach (#data){
print $_->[$idcol], "\n";
}
#_ is a completely different variable from $_ and is unpopulated here.
You should also consider using
while (my $row = <FILE>) { ... }
to read your file. It reads only a single line at a time whereas for will read the entire file into a list of lines before iterating over it.
I recommend to avoid parsing the CSV file directly and using the Text::CSV module.
use Text::CSV;
use Carp;
#set command line arguments
my ($infi, $outdir, $idcol) = #ARGV;
my $csv = Text::CSV->new({
sep_char => "\t"
});
open(my $fh, "<:encoding(UTF-8)", $infi) || croak "can't open $infi: $!";
# Uncomment if you need to skip header line
# <$fh>;
while (<$fh>) {
if ($csv->parse($_)) {
my #columns = $csv->fields();
print "$columns[0]\t$columns[1]\t$columns[2]\n";
} else {
my $err = $csv->error_input;
print "Failed to parse line: $err";
}
}
close $fh;
I have a simple .csv file that has that I want to extract data out of a write to a new file.
I to write a script that reads in a file, reads each line, then splits and structures the columns in a different order, and if the line in the .csv contains 'xxx' - dont output the line to output file.
I have already managed to read in a file, and create a secondary file, however am new to Perl and still trying to work out the commands, the following is a test script I wrote to get to grips with Perl and was wondering if I could aulter this to to what I need?-
open (FILE, "c1.csv") || die "couldn't open the file!";
open (F1, ">c2.csv") || die "couldn't open the file!";
#print "start\n";
sub trim($);
sub trim($)
{
my $string = shift;
$string =~ s/^\s+//;
$string =~ s/\s+$//;
return $string;
}
$a = 0;
$b = 0;
while ($line=<FILE>)
{
chop($line);
if ($line =~ /xxx/)
{
$addr = $line;
$post = substr($line, length($line)-18,8);
}
$a = $a + 1;
}
print $b;
print " end\n";
Any help is much appreciated.
To manipulate CSV files it is better to use one of the available modules at CPAN. I like Text::CSV:
use Text::CSV;
my $csv = Text::CSV->new ({ binary => 1, empty_is_undef => 1 }) or die "Cannot use CSV: ".Text::CSV->error_diag ();
open my $fh, "<", 'c1.csv' or die "ERROR: $!";
$csv->column_names('field1', 'field2');
while ( my $l = $csv->getline_hr($fh)) {
next if ($l->{'field1'} =~ /xxx/);
printf "Field1: %s Field2: %s\n", $l->{'field1'}, $l->{'field2'}
}
close $fh;
If you need do this only once, so don't need the program later you can do it with oneliner:
perl -F, -lane 'next if /xxx/; #n=map { s/(^\s*|\s*$)//g;$_ } #F; print join(",", (map{$n[$_]} qw(2 0 1)));'
Breakdown:
perl -F, -lane
^^^ ^ <- split lines at ',' and store fields into array #F
next if /xxx/; #skip lines what contain xxx
#n=map { s/(^\s*|\s*$)//g;$_ } #F;
#trim spaces from the beginning and end of each field
#and store the result into new array #n
print join(",", (map{$n[$_]} qw(2 0 1)));
#recombine array #n into new order - here 2 0 1
#join them with comma
#print
Of course, for the repeated use, or in a bigger project you should use some CPAN module. And the above oneliner has much cavetas too.
I'm new to Perl and I have a CSV file that contains e-mails and names, like this:
john#domain1.com;John
Paul#domain2.com;
Richard#domain3.com;Richard
Rob#domain4.com;
Andrew#domain5.com;Andrew
However, as you can see a few entries/lines have the e-mail address and the ; field separator, but lack the name. I need to read line by line and and if the name field is missing, I want to print in this place the begin of the e-mail until #domainX.com. Output example:
john#domain1.com;John
Paul#domain2.com;Paul
Richard#domain3.com;Richard
Rob#domain4.com;Rob
Andrew#domain5.com;Andrew
I'm new with Perl, I did the iteration of read line by line, such this:
#!/usr/bin/perl
use warnings;
use strict;
open (MYFILE, 'test.txt');
while (<MYFILE>) {
chomp;
}
But I'm failing to parse the entries to use ; as a separator and to check if the name field is missing and consequently print the begin of the e-mail without the domain.
Can someone please give me a example based on my code?
First, if the file may contain real CSV (or space SV in your case) data (e.g. quoted fields), I'd strongly recommend using a standard Perl module to parse it.
Otherwise, a quick-and-dirty example can be:
#!/usr/bin/perl
use warnings;
use strict;
# In modern Perl, please always use 3-aqr form of open and lexical filehandles.
# More robust
open $fh, "<", 'test.txt' || die "Can not open: $!\n";
while (<$fh>) {
chomp;
my ($email, name) = split(/;/, $_);
if (!$name) {
my ($userid, $domain) = split(/\#/, $email);
$name = $userid;
}
print "$space_prefix$email;$name\n"; # Print to STDOUT for simplicity of example
}
close($fh);
Try:
#!/usr/bin/env perl
use strict;
use warnings;
for my $file ( #ARGV ){
open my$in_fh, '<', $file or die "could not open $file: $!\n";
while( my $line = <$in_fh> ){
chomp( $line );
my ( $email, $name ) = split m{ \; }msx, $line;
if( ! ( defined $name && length( $name ) > 0 ) ){
( $name ) = split m{ \# }msx, $email;
$name = ucfirst( lc( $name ));
}
print "$email;$name\n";
}
}
I am not a pearl programmer, but I would split first on the space character, and then you could iterate through the results and split by the semi-colon. Then you can check the second member of the semi-colon split array, and if it is empty, replace it with the beginning of the first member of the semi-colon split array. Then, just reverse the process, first joining by semi-colons and then by spaces.
I need some perl help in putting these (2) processes/code to work together. I was able to get them working individually to test, but I need help bringing them together especially with using the loop constructs. I'm not sure if I should go with foreach..anyways the code is below.
Also, any best practices would be great too as I'm learning this language. Thanks for your help.
Here's the process flow I am looking for:
read a directory
look for a particular file
use the file name to strip out some key information to create a newly processed file
process the input file
create the newly processed file for each input file read (if i read in 10, I create 10 new files)
Part 1:
my $target_dir = "/backups/test/";
opendir my $dh, $target_dir or die "can't opendir $target_dir: $!";
while (defined(my $file = readdir($dh))) {
next if ($file =~ /^\.+$/);
#Get filename attributes
if ($file =~ /^foo(\d{3})\.name\.(\w{3})-foo_p(\d{1,4})\.\d+.csv$/) {
print "$1\n";
print "$2\n";
print "$3\n";
}
print "$file\n";
}
Part 2:
use strict;
use Digest::MD5 qw(md5_hex);
#Create new file
open (NEWFILE, ">/backups/processed/foo$1.name.$2-foo_p$3.out") || die "cannot create file";
my $data = '';
my $line1 = <>;
chomp $line1;
my #heading = split /,/, $line1;
my ($sep1, $sep2, $eorec) = ( "^A", "^E", "^D");
while (<>)
{
my $digest = md5_hex($data);
chomp;
my (#values) = split /,/;
my $extra = "__mykey__$sep1$digest$sep2" ;
$extra .= "$heading[$_]$sep1$values[$_]$sep2" for (0..scalar(#values));
$data .= "$extra$eorec";
print NEWFILE "$data";
}
#print $data;
close (NEWFILE);
You are using an old-style of Perl programming. I recommend you to use functions and CPAN modules (http://search.cpan.org). Perl pseudocode:
use Modern::Perl;
# use...
sub get_input_files {
# return an array of files (#)
}
sub extract_file_info {
# takes the file name and returs an array of values (filename attrs)
}
sub process_file {
# reads the input file, takes the previous attribs and build the output file
}
my #ifiles = get_input_files;
foreach my $ifile(#ifiles) {
my #attrs = extract_file_info($ifile);
process_file($ifile, #attrs);
}
Hope it helps
I've bashed your two code fragments together (making the second a sub that the first calls for each matching file) and, if I understood your description of the objective correctly, this should do what you want. Comments on style and syntax are inline:
#!/usr/bin/env perl
# - Never forget these!
use strict;
use warnings;
use Digest::MD5 qw(md5_hex);
my $target_dir = "/backups/test/";
opendir my $dh, $target_dir or die "can't opendir $target_dir: $!";
while (defined(my $file = readdir($dh))) {
# Parens on postfix "if" are optional; I prefer to omit them
next if $file =~ /^\.+$/;
if ($file =~ /^foo(\d{3})\.name\.(\w{3})-foo_p(\d{1,4})\.\d+.csv$/) {
process_file($file, $1, $2, $3);
}
print "$file\n";
}
sub process_file {
my ($orig_name, $foo_x, $name_x, $p_x) = #_;
my $new_name = "/backups/processed/foo$foo_x.name.$name_x-foo_p$p_x.out";
# - From your description of the task, it sounds like we actually want to
# read from the found file, not from <>, so opening it here to read
# - Better to use lexical ("my") filehandle and three-arg form of open
# - "or" has lower operator precedence than "||", so less chance of
# things being grouped in the wrong order (though either works here)
# - Including $! in the error will tell why the file open failed
open my $in_fh, '<', $orig_name or die "cannot read $orig_name: $!";
open(my $out_fh, '>', $new_name) or die "cannot create $new_name: $!";
my $data = '';
my $line1 = <$in_fh>;
chomp $line1;
my #heading = split /,/, $line1;
my ($sep1, $sep2, $eorec) = ("^A", "^E", "^D");
while (<$in_fh>) {
chomp;
my $digest = md5_hex($data);
my (#values) = split /,/;
my $extra = "__mykey__$sep1$digest$sep2";
$extra .= "$heading[$_]$sep1$values[$_]$sep2"
for (0 .. scalar(#values));
# - Useless use of double quotes removed on next two lines
$data .= $extra . $eorec;
#print $out_fh $data;
}
# - Moved print to output file to here (where it will print the complete
# output all at once) rather than within the loop (where it will print
# all previous lines each time a new line is read in) to prevent
# duplicate output records. This could also be achieved by printing
# $extra inside the loop. Printing $data at the end will be slightly
# faster, but requires more memory; printing $extra within the loop and
# getting rid of $data entirely would require less memory, so that may
# be the better option if you find yourself needing to read huge input
# files.
print $out_fh $data;
# - $in_fh and $out_fh will be closed automatically when it goes out of
# scope at the end of the block/sub, so there's no real point to
# explicitly closing it unless you're going to check whether the close
# succeeded or failed (which can happen in odd cases usually involving
# full or failing disks when writing; I'm not aware of any way that
# closing a file open for reading can fail, so that's just being left
# implicit)
close $out_fh or die "Failed to close file: $!";
}
Disclaimer: perl -c reports that this code is syntactically valid, but it is otherwise untested.