Add Column to CSV Windows PowerShell

Question

I have a fairly standard csv file with headers I want to add a new column & set all the rows to the same data.

Original:

column1, column2
1,b
2         


        

Answer 1

For some applications, I found that producing a hashtable and using the .values as the column to be good (it would allow for cross reference validation against another object that was being enumerated).

In this case, #powershell on freenode brought my attention to an ordered hashtable (since the column header must be used).

Here is an example without any validation the .values

$newcolumnobj =  [ordered]@{}
#input data into a hash table so that we can more easily reference the `.values` as an object to be inserted in the CSV
$newcolumnobj.add("volume name", $currenttime)

#enumerate $deltas [this will be the object that contains the volume information `$volumedeltas`)
#  add just the new deltas to the newcolumn object
foreach ($item in $deltas){ 
  $newcolumnobj.add($item.volume,$item.delta)
}

$originalcsv = @(import-csv $targetdeltacsv)

#thanks to pscookiemonster in #powershell on freenode
for($i=0; $i -lt $originalcsv.count; $i++){
  $originalcsv[$i] | Select-Object *, @{l="$currenttime"; e={$newcolumnobj.item($i)}}
}

Example is related to How can I perform arithmetic to find differences of values in two CSVs?