Need Help Understanding Difference Between Get-Content and Import-Csv in Powershell
I'm Having Trouble Understanding When to Use Get-Content and When to Use Import-Csv for Modifying a Csv File. Here Is an Example of My File, Which Is an Output...
I'm having trouble understanding when to use Get-Content and when to use Import-Csv for modifying a CSV file. Here is an example of my file, which is an output of a hash table:
Name Key Value
AOI1\\ABC1 AOI1\\ABC1 TRUE
AOI2\\DEF2 AOI2\\DEF2 TRUE
\#AOI3\#\\GHI3 \#AOI3\#\\GHI3 FALSE
I need to do the following to the file:
- Remove '\\' and everything after it in the Name column
- Remove '\\' and everything before it in the Key column
- Replace '\#' with '#' in the last row
- Rename the column headers
The result should look like this:
Loc FName Result
AOI1 ABC1 TRUE
AOI2 DEF2 TRUE
#AOI3# GHI3 FALSE
For removing the '\\' and everything after in the Name column, I came up with this script:
Import-Csv c:\test.csv |
% {$_.Name.split('\\\\')[0]}
This outputs the following:
AOI1
AOI2
However, I want to be able to write everything back to the same Csv file, so I tried changing it to:
Get-Content c:\test.csv |
% {$_.Name.split('\\\\')[0]}
However, I ended up with a "You cannot call a method on a null-valued expression" error message. If I keep the Import-Csv and modify the script to also do item 4, I get the same error message. Here's that script:
Import-Csv U:\To_Delete\Layer_search\results_STACK_layers.csv |
Select-Object @{n='AOI';e={$_.'Name'}}, @{n='LAYER';e={$_.'Key'}}, @{n='IN MAP';e={$_.'Value'}} |
% {$_.Name.split('\\\\')[0]}
So, how do I modify my CSV and output it to the same CSV afterwards? What could be causing that error message?
Sorry for the long-winded post, but I wanted to provide enough examples.
Thanks!
1 Answer
presuming you cannot use the advice from Bill_Stewart about fixing the source, here is one way to do the conversion. [grin] part of your problem was your use of the string split method instead of the string split operator. the 1st treats every character as a split target. the 2nd uses regex to split on the split string instead of on the characters in the split string.
# fake reading in a CSV file
# in real life, use Import-CSV
$InStuff = @'
Name, Key, Value
AOI1\\ABC1, AOI1\\ABC1, TRUE
AOI2\\DEF2, AOI2\\DEF2, TRUE
\#AOI3\#\\GHI3, \#AOI3\#\\GHI3, FALSE
'@ | ConvertFrom-Csv
$Results = foreach ($IS_Item in $InStuff)
{
[PSCustomObject]@{
# new version removes the unwanted "\" from the ends of the "Loc" value
#Loc = ($IS_Item.Name -split [regex]::Escape('\\'))[0]
Loc = ($IS_Item.Name -split [regex]::Escape('\\'))[0].Replace('\')
FName = ($IS_Item.Key -split [regex]::Escape('\\'))[1]
Result = [convert]::ToBoolean($IS_Item.Value)
}
}
# on screen
$Results
# send to a CSV file
$Results |
Export-Csv -LiteralPath "$env:TEMP\Heather_RearrangedCSV.csv" -NoTypeInformation
on screen ...
Loc FName Result
--- ----- ------
AOI1 ABC1 True
AOI2 DEF2 True
#AOI3# GHI3 False
CSV file content ...
"Loc","FName","Result"
"AOI1","ABC1","True"
"AOI2","DEF2","True"
"#AOI3#","GHI3","False"
Elena Rostova holds a Master's degree in Public Health Journalism. She covers groundbreaking medical research, holistic wellness trends, mental health awareness, and nutritional science.
