Using PowerShell, how would I create/split a file in 1-week chunks?

Question

This is in reference to the post here: How to delete date-based lines from files using PowerShell

Using the below code (contributed by 'mjolinor') I can take a monolithic (pipe "|" delimited) CSV file and create a trimmed CSV file with only lines containing dates less than $date:

$date = '09/29/2011'
foreach ($file in gci *.csv) {
    (gc $file) |
     ? {[datetime]$_.split('|')[1] -lt $date
     } | set-content $file
 }

The above code works great! What I need to do now is create additional CSV files from the monolithic CSV file with lines containing dates >= $date, and each file needs to be in 1-week chunks going forward from $date.

For example, I need the following 'trimmed' CSV files (all created from original CSV):

All dates less than 09/30/2011 (already done with code above)
File with date range 09/30 - 10/6
File with date range 10/7 - 10/14
Etc, etc, until I reach the most recent date

Bas Bossink · Accepted Answer · 2012-03-08 21:24:58Z

3

You can use the GetWeekOfYear method of Calendar like this

$date = (Get-Date)
$di = [Globalization.DateTimeFormatInfo]::CurrentInfo
$week = $di.Calendar.GetWeekOfYear($date, $di.CalendarWeekRule, $di.FirstDayOfWeek)

to determine the week number of a given date.

answered Mar 8, 2012 at 21:24

Bas Bossink

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mjolinor · Accepted Answer · 2012-03-08 22:19:53Z

2

This is NOT tested with your input (it was adapted from some script I use for time-slicing and counting Windows log events), but should be close to working. It can create files on any arbitrary time span you designate in $span:

 $StartString = '09/29/2011'
 $inputfile = 'c:\somedir\somefile.csv'

 $Span = new-timespan -days 7
 $lines = @{}

 $TimeBase = [DateTime]::MinValue
 $StartTicks = ([datetime]$startString).Ticks
 $SpanTicks = $Span.Ticks

 get-content $inputfile |
  foreach {
     $dt = [datetime]$_.split('|')[1]
     $Time_Slice = [int][math]::truncate(($dt.Ticks - $StartTicks) / $SpanTicks)
     $lines[$Time_Slice] += @($_)
     }

  $lines.GetEnumerator() |
      foreach {
       $filename = ([datetime]$StartString + [TimeSpan]::FromTicks($SpanTicks * $_.Name)).tostring("yyyyMMdd") + '.csv'
       $_.value | export -csv $filename
   }

answered Mar 8, 2012 at 22:19

mjolinor

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1 Comment

Keith Over a year ago

mjolinor -- thank you! I'll play around with your code and see if I can get it to work for me.

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