Powershell loop to read into array from an imported CSV

Question

I have a script that imports a CSV which I then read certain values into an array.

How can I use a loop to make this better?

$list = Import-Csv "c:\temp\list.csv"

$array_list = @()

foreach ($item in $list) {

$array_list += $item.position1

$array_list += $item.position2

$array_list += $item.position3

$array_list += $item.position4

$array_list += $item.position5

$array_list += $item.position6

$array_list += $item.position7

$array_list += $item.position8

$array_list += $item.position9

$array_list += $item.position10

}

So you literally just want to add every field into a flat array? — EBGreen
– EBGreen, Commented Jul 9, 2018 at 23:10
There are other fields but I want to add these 10 into an array. — amaru96
– amaru96, Commented Jul 9, 2018 at 23:20

EBGreen · Accepted Answer · 2018-07-09 23:42:50Z

2

There are a few ways. Here is one:

$array_list = @()
foreach($row in (Get-Content c:\temp\List.csv | Select-Object -Skip 1)){
    $array_list += ($row.split(','))[0..9]
}

You might have to tweak it a little if there are spaces or quotes that you don't want.

If you want to do it based on the property name:

$contents = Import-CSV C:\temp\Test.csv
$propertyNames = gm -in $contents[0] | ?{$_.name -like '*position*'} | select -expand name
$array_list = @()
foreach($row in $contents){
    foreach($name in $propertyNames){
        $array_list += $row.$name
    }
}

edited Jul 9, 2018 at 23:42

answered Jul 9, 2018 at 23:26

EBGreen

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10 Comments

amaru96 Over a year ago

This looks like it will add all the fields into the array. The CSV has other fields like name, surname, location, etc. I only want to use the fields specifically called "position" which range from position1 to position10 - hope that makes sense.

amaru96 Over a year ago

Yes, correct it is not the first 10. But I used your code to specify the positions and it worked, so thanks for pointing me in the right direction. And there was a slight error in the code, $result should be $array_list.

user6811411 Over a year ago

I'd try to avoid += which will rebuild $array_list each time $array_list = foreach($row in (Get-Content c:\temp\List.csv | Select-Object -Skip 1)){ ($row.split(','))[0..9]} same for your new variant.

EBGreen Over a year ago

Yeah, I was just keeping it true to the method used in the question. To be honest I pretty much always use ArrayLists anyway. :)

EBGreen Over a year ago

Well $import[5] would return the 6th object in the array. So all the properties on that object. $import.surname would return all of the surname values from all of the objects in the array (depending on your version of Powershell). If you want the surname of the 6th object then it would be $import[5].surname.

|

mklement0 · Accepted Answer · 2018-07-10 03:30:54Z

If your intent is to simply extract a subset of the columns in the CSV, you can simply use Select-Object:

$array = Import-Csv "c:\temp\list.csv" | Select-Object -Property position*

Note the use of a wildcard pattern to select the properties to extract; matching columns are extracted in input order, so if the CSV contains columns position0, position1, ... position10 in that order (possibly interspersed with differently named columns), then the output collected in $array (which is of type [object[]]) contains custom objects with properties named for those columns - in order - containing the respective rows' column values.

(Of course, you can explicitly enumerate the columns to extract by passing them as an array to Select-Object -Property (e.g., Select-Object -Property position4, position 7), and you can even mix literal column names with wildcard expressions in the argument array.)

If you actually meant to collect the position* column values in a single, flat array across all input rows (PSv3+):

$array = Import-Csv "c:\temp\list.csv" | Select-Object -Property position* |
  ForEach-Object { $_.psobject.properties.value }

TessellatingHeckler · Accepted Answer · 2018-07-09 23:47:09Z

1

$fields = 'position1', 'position2', 'position3', 'position4', 
          'position5', 'position6', 'position7', 'position8', 
          'position9', 'position10'


$array = foreach ($line in Import-Csv "c:\temp\list.csv")
{
    $fields | foreach-object {
        $line.$_
    }
}

answered Jul 9, 2018 at 23:47

TessellatingHeckler

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