Powershell: Re-order rows in file by date - sorting

Question

I have an input file like this:
Peter,Melbourne,30.5.1982
Simon,Sydney,21.2.1990
Tom,Adelaide,22.9.1980
What I'd like to do is re-order the content of the file by the date column and save it to a file.
Like:
Tom,Adelaide,22.9.1980
Peter,Melbourne,30.5.1982
Simon,Sydney,21.2.1990
The whole thing should be done in Powershell..
Cheers!

Answer 1

#vonPryz put a good answer, you can do it a bit shorter.
# Read input data
$c = Import-Csv -Header #("Name","City","Date") c:\temp\data.txt -Delimiter ","
# Get the good globalization info
$oz = new-object Globalization.CultureInfo("en-AU")
#
$c | Sort-Object {[System.DateTime]::Parse($_.date, $oz)}
# Write output data
$d | Export-Csv c:\temp\datasSortedVyDate.csv -NoTypeInformation

Answer 2

Use Import-CSV to read the data. Then convert each date to a DateTime object, so sorting will compare dates, not strings. Finally, sort the CSV data by Date column. Like so,
# Read input data
$c = Import-Csv -Header #("Name","City","Date") c:\temp\data.txt -Delimiter ","
# Print the data. This looks just like what we have read from the file
$c
Name City Date
Peter Melbourne 30.5.1982
Simon Sydney 21.2.1990
Tom Adelaide 22.9.1980
Let's sort the data
$c | sort -Property Date
Name City Date
Simon Sydney 21.2.1990
Tom Adelaide 22.9.1980
Peter Melbourne 30.5.1982
Huh? Sorting didn't work. This is as the Date column contains string values. In string sorting, the sort doesn't care about year part, as two first characters are enough to sort strings. This is common a caveat.
How to overcome this? One needs to convert the date into date objects that will sort nicely by comparing year and month parts too. First off, create a culture info that is used to tell if you are using mm-dd-yyyy, dd-mm-yyyy, or some other format.
# Eh, mate, Melbourne is down under
$oz = new-object Globalization.CultureInfo("en-AU")
# Loop through each row and convert the date member to date, using Aussie culture.
for($i=0;$i -ne $c.count; $i++) {
$c[$i].Date = [Convert]::ToDateTime($c[$i].Date, $oz)
}
# Now the sort works as expected:
$c | sort -Property Date
Name City Date
Tom Adelaide 22.9.1980 0:00:00
Peter Melbourne 30.5.1982 0:00:00
Simon Sydney 21.2.1990 0:00:00