Need to convert data as string into an Excel readable format - perl

Question

I have a file with data that includes date strings in this format:
June 11, 2012 3:47:56 PM GMT-07:00
I'm already using a Perl script to manipulate some other data elements from that file then outputting it as a csv for Excel. Rather than fooling about with functions and formulas in Excel to try to translate the date-as-string into something Excel can read, I figure I should be able to do it easier/quicker in Perl.
The purpose / desired end result is a time & date stamp that I can do simple math on in Excel (i.e, get age difference between entries by mathing the time stamps).
To that end, I want to end up with my datestamps looking like this:
6/11/2012 3:47:56 PM
Really I just need to convert the date, the time is perfect, and remove the GMT differential garbage.
I've seen code snippets and references to modules that seem to convert the other way ... i.e., from "6/24/12" to "June 24, 2012", but that's going the wrong direction for me.
I looked up module time::piece in cpan, but don't really understand it. I'm working in a Cygwin exec, so not a real unix system, and don't have much in the way of man pages or perldocs.

Answer 1

You can use module Date::Parse and POSIX functions strftime. There are plenty modules in CPAN, which can parse dates.
Formatting dates with strftime really cool article
use strict;
use Date::Parse;
use POSIX qw/strftime/;
my $time = str2time( 'June 11, 2012 3:47:56 PM GMT-07:00' );
my $date = strftime "%m/%d/%Y %H:%M:%S %p", localtime($time);
print $date;
Good luck!

Answer 2

If you original string is: $timestring, then this should work (not tested):
my %months = (January => '1', February =>'2', March => '3', ...);
...
etc.
$timestring =~ s<^(w+)\x20(\d{1,2}),\x20(\d{4})(\x20\(?:\d{1,2}\:){2}\d{1,2}\x20PM).*$><"$months{$1}/$2/$3$4">eeg

Answer 3

use DateTime;
use DateTime::Format::Strptime;
# YOU MUST ADAPT THIS PATTERN
my $pat = "%b %d, %Y"; #incomplete
my $d = DateTime::Format::Strptime->new( pattern => $pat, on_error => 'croak' );
my $dt = $d->parse_datetime($strdate);
say $dt->mdy("/") . " " . $dt->hms(":") . " " . $dt->am_or_pm;
But note that Excel prefers Datetime types in ISO Format:
say $dt->ymd('-') . 'T' . $dt->hms(':');
For finetuning the pattern $pat, read the module documentation for DateTime::Format::Strptime.
It works best for parsing input data that is very uniform. Encounter the slightest deviation and the module won't parse it (you can work around this, though)

Answer 4

Many people have their favorite time parsing techniques. I like Time::Piece because it comes with Perl (at least any version over 5.10):
my $time_string = "June 11, 2012 3:47:56 PM GMT-7:00";
my $time_string =~ / GMT.*$//; # That "GMT-7:00" messes things up!
say $time_string # June 11, 2012 3:47:56 PM GMT
my $time = Time::Piece->strptime(
$time_string, "%B %d, %Y %l:%M:%S %p" );
say $time->strftime("%D %l:%M:%S %p");
The $foo->bar is object oriented coding style which is becoming the way of the future in Perl, so you better get use to it.
It's not really all that complex. Basically, you create an container that holds all your data. Sort of the way a hash can hold various pieces of information.
When I do this:
my $time = Time::Piece->strptime( "$time_string", "$time_format" );
I'm creating a Time::Piece object (nee container) called $time which stores the time.
When you say $time->Weekday, you are actually executing a subroutine called Weekday that takes your $time container, extracts the information from it, parses the time, and return the weekday.
The strptime (STRing Parse TIME) constructor (which is the function that creates your container) is taking your time string (the first argument), and the format it is in (the second argument) and creating that $time object. The various %M and %d specify particular time fields. These can be found in the strptime manpage.
You can play around with these formats with the Unix date command:
$ date "+%m/%d/%y"
08/23/13
$ date "+%m/%d/%Y"
08/23/2013
$ date "%Y-%m-%d"
2013-08-23
That might make you feel more comfortable with them.
The strftime (STRing Format TIME) method (nee subroutine) is the opposite of strptime. This takes the time (which is in $time and returns the time in the format you specified.

Answer 5

If you have problems installing new extra packages you can do that using plain per. Once you have the excel date serial value e.g 61,59340278 you can use Excel to format the appearance of that number in a custom date.
For example:
61,59340278 is displayed in Excel using custom date format
CUSTOM Cell format: TT.MM.JJJJ hh:mm:ss
as> 01.03.1900 14:14:30
Below the functions
sub date2excelvalue {
my($day1, $month, $year, $hour, $min, $sec) = #_;
my #cumul_d_in_m = (0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365);
my $doy = $cumul_d_in_m[$month - 1] + $day1;
#
full years + your day
for my $y(1900..$year) {
if ($y == $year) {
if ($month <= 2) {
#
dont add manually extra date
if inJanuary or February
last;
}
if ((($y % 4 == 0) && ($y % 100 != 0)) || ($y % 400 == 0) || ($y == 1900)) {
$doy++;#
leap year
}
} else {#
full years
$doy += 365;
if ((($y % 4 == 0) && ($y % 100 != 0)) || ($y % 400 == 0) || ($y == 1900)) {
$doy++;#
leap year
}
}
}#
end
for y# calculate second parts as a fraction of 86400 seconds
my $excel_decimaltimepart = 0;
my $total_seconds_from_time = ($hour * 60 * 60 + $min * 60 + $sec);
if ($total_seconds_from_time == 86400) {
$doy++;#
just add a day
} else {#
add decimal in excel
$excel_decimaltimepart = $total_seconds_from_time / (86400);
$excel_decimaltimepart = ~s / 0\. //;
}
return "$doy\.$excel_decimaltimepart";
}
sub excelvalue2date {
my($excelvalueintegerpart, $excelvaluedecimalpart) = #_;
my #cumul_d_in_m = (0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365);
my #cumul_d_in_m_leap = (0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366);
my #cumul_d_in_m_selected;
my($day1, $month, $year, $hour, $min, $sec);
$day1 = 0;#
all days all years
my $days_in_year;
my $acumdays_per_month;
my $daysinmonth;
my $day;
#
full years + your day
for my $y(1900. .3000) {
my $leap_year = 0;#
leap year
my $leap_year_mask = 0;#
leap year
if ((($y % 4 == 0) && ($y % 100 != 0)) || ($y % 400 == 0) || ($y == 1900)) {
$leap_year = 1;#
leap year
#cumul_d_in_m_selected = #cumul_d_in_m_leap;
} else {
$leap_year = 0;#
leap year
#cumul_d_in_m_selected = #cumul_d_in_m;
}
if (($day1 + (365 + $leap_year)) > $excelvalueintegerpart) {
#
found this year $y
$year = $y;
print "year $y\n";
$days_in_year = $excelvalueintegerpart - $day1;
$acumdays_per_month = 0;
print "excelvalueintegerpart $excelvalueintegerpart\n";
print "day1 $day1\n";
print "daysinyear $days_in_year\n";
for my $i(0..$# cumul_d_in_m) {
if ($i == $# cumul_d_in_m) {
$month = $i + 1;#
month 12 December
$day = $days_in_year - $cumul_d_in_m_selected[$i];
last;
} else {
if (($days_in_year > ($cumul_d_in_m_selected[$i])) && ($days_in_year <= ($cumul_d_in_m_selected[$i + 1]))) {
$month = $i + 1;
$day = $days_in_year - $cumul_d_in_m_selected[$i];
last;
}
}
}#
end
for $i months
# end year
last;
} else {#
full years
$day1 += (365 + $leap_year);
}
}#
end
for years interger part comparator
my $total_seconds_inaday;
$total_seconds_inaday = "0\.$excelvaluedecimalpart" * 86400;
$sec = $total_seconds_inaday;
$hour = int($sec / (60 * 60));
$sec -= $hour * (60 * 60);
$min = int($sec / 60);
$sec -= $min * (60);
$sec = int($sec);
return ($day, $month, $year, $hour, $min, $sec);
}
my $excelvariable = date2excelvalue(1, 3, 2018, 14, 14, 30);
print "Excel variable: $excelvariable\n";
my($integerpart, $decimalwithoutzero) = ($1, $2) if ($excelvariable = ~m / (\d + )\.(\d + ) / );
my($day1, $month, $year, $hour, $min, $sec) = excelvalue2date($integerpart, $decimalwithoutzero);
print "Excel Date from value: $day1, $month, $year, $hour, $min, $sec\n";
Enjoy it!