CODEWITHSUNDEEP
csvpowershell
Andrew
Andrew

Reputation: 33

powershell csv select every nth line

I am using Powershell to process a CSV file containing lines of coordinate values.

Rows 1 and 2 are radians which I have converted to Lat Long values.

I have come up with the script below which works.

My problem is that I don't want every line - it's too many. I want to extract every 1000th line.

foreach ($FileName in get-item $dir\*.* -include test1.csv )
{
$FilenameNP = $Filename | select  -expand BaseName
Write-Host $FilenameNP
Write-Output "Latitude,Longitude,Altitude,TimeSeconds,LatitudeRadians,LongitudeRadians,AltitudeMeters,x velocity meters/second ,y velocity meters/second ,z velocity meters/second ,Roll radians ,Pitch radians ,platform heading radians ,wander angle radians ,x body acceleration meters/second2 ,y body acceleration meters/second2 ,z body acceleration meters/second2 ,x body angular rate radians/second ,y body angular rate radians/second ,z body angular rate radians/second " > $dir\Sbet_$FilenameNP.txt


$Content = get-content $Filename

Write-host $Content


foreach ($Line in $Content)
    {
    $Latitude=$null
    $Longitude=$null
    $Line=$Line -replace '\s+',''
    $LineS=$Line  -split ","
    $Latitude=([decimal]$LineS[1]*180/[math]::pi)
    $Longitude=([decimal]$LineS[2]*180/[math]::pi)
    $Altitude=$LineS[3]
    Write-Host $Latitude $Longitude $Altitude

    write-Output "$Latitude,$Longitude,$Altitude,$Line" >> $dir\Sbet_$FilenameNP.txt

  }
}

Data looks like this: 

385278.0020318,     -0.6458227,      3.0509169,     39.0372952,      0.0044346,      0.0046028,
385278.0070309,     -0.6458227,      3.0509169,     39.0373095,      0.0036458,      0.0019423,
385278.0120310,     -0.6458230,      3.0509170,     45.1586564,      0.0025192,     -0.0011160,
385278.0170301,     -0.6458230,      3.0509170,     45.1586851,      0.0013969,     -0.0034220,
385278.0220292,     -0.6458230,      3.0509170,     45.1587176,      0.0002427,     -0.0041081,
385278.0270284,     -0.6458230,      3.0509170,     45.1587510,     -0.0006602,     -0.0027870,
385278.0320285,     -0.6458230,      3.0509170,     45.1587844,     -0.0012237,     -0.0001119,

Upvotes: 3

Views: 4450

Answers (2)

TheMadTechnician
TheMadTechnician

Reputation: 36297

Don't loop through every line if you don't want every line... Use a For loop and have it iterate at what ever line count you want to extract...

foreach ($FileName in get-item $dir\*.* -include test1.csv )
{
    $FilenameNP = $Filename | select  -expand BaseName
    Write-Host $FilenameNP
    Write-Output "Latitude,Longitude,Altitude,TimeSeconds,LatitudeRadians,LongitudeRadians,AltitudeMeters,x velocity meters/second ,y velocity meters/second ,z velocity meters/second ,Roll radians ,Pitch radians ,platform heading radians ,wander angle radians ,x body acceleration meters/second2 ,y body acceleration meters/second2 ,z body acceleration meters/second2 ,x body angular rate radians/second ,y body angular rate radians/second ,z body angular rate radians/second " > $dir\Sbet_$FilenameNP.txt

    $Content = get-content $Filename

    Write-host $Content
    For($i = 0;$i -lt $Content.count;$i=$i+1000){
        $Latitude=$null
        $Longitude=$null
        $Line=$Content[$i] -replace '\s+',''
        $LineS=$Line  -split ","
        $Latitude=([decimal]$LineS[1]*180/[math]::pi)
        $Longitude=([decimal]$LineS[2]*180/[math]::pi)
        $Altitude=$LineS[3]
        Write-Host $Latitude $Longitude $Altitude

        write-Output "$Latitude,$Longitude,$Altitude,$Line" >> $dir\Sbet_$FilenameNP.txt
    }
}

Upvotes: 2

nathanchere
nathanchere

Reputation: 8098

$counter = 0
Foreach ($Line in $Content)
{
    $counter++
    if($counter -ne 10000) {continue}        
    $counter = 0

    # Proceed as normal here
    $Latitude=$null
    $Longitude=$null
    ... etc
}

Upvotes: 1

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