Call Powershell Import-Csv cmdlet with variable -Header

Question

The total number and position of fields vary from file to file, but the fields in which I am interested are always present. File1.csv looks like this:

1,1.0,one
2,2.0,two

See code below:

function Read_Headers_From_File($filename)
{
    # Yes, I am not reading a file right now
    "int,float,string"
}

$header1 = Read_Headers_From_File("file1.ini")
$file1 = Import-Csv -Header $header1 file1.csv
# $header2 = Read_Headers_From_File("file2.ini")
# $file2 = Import-Csv -Header $header2 file2.csv
echo $file1

The output is:

int,float,string
----------------
1
2

The "int,float,string" is interpreted as a single field named "int,float,string". Is there a way to make -Header "field1,field2,field3" work like -Header field1,field2,field3?

Suggest you edit this question to better explain the problem and the desired results. — Χpẘ
– Χpẘ, Commented Mar 12, 2016 at 1:36

Χpẘ · Accepted Answer · 2016-03-12 00:23:45Z

2

You can do this to exclude a column, say y:

$userdata = Import-Csv test.csv | select-object * -exclude y

Although you didn't ask you can do this to rename columns:

# Assume you want to use the header names x,y,z instead of what 
# is specified in the header line of the file
# The Header parameter allows you to specify headers for a CSV that (nominally)
# doesn't contain a header line. But if the CSV file does contain a header line
# and -Header is specified then the header line is treated like a data line.
# The select -skip 1 discards the header-line-as-data row

$userdata = Import-Csv -Header x,y,z test.csv | select-object -skip 1

edited Mar 12, 2016 at 0:23

answered Mar 12, 2016 at 0:12

Χpẘ

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4 Comments

Test User Over a year ago

Good to know, but my issue is that the names of the columns are fixed but the positions are variable, so I wanted to dynamically create headers to match the known positions read from a file. I suppose that I could just copy the file to a new file with dynamically-created headers included and then call Import-Csv.

Χpẘ Over a year ago

You could just rename the columns. If the columns are labeled x,y,z, but are really z,x,y, then rename the columns to be z,x,y as the second part of the answer explains.

Test User Over a year ago

Remember my source CSV file does not have headers to be renamed. It seems that I can't add headers on the fly with -Headers, so the solution is to create a new file dest.csv with the headers that I want and populate it with the contents of source.csv.

Χpẘ Over a year ago

The OP doesn't say your CSV doesn't have headers, so no I don't remember that. -Header (no "s") is exactly for specifying headers on the fly. Please edit the OP to make your question and desired results more clear.

Test User · Accepted Answer · 2016-03-12 10:35:00Z

0

I edited the question radically. What I want can be achieved by this:

$header1 = Read_Headers_From_File("file1.ini")
$file1 = Invoke-Expression ("Import-Csv " + "-Header " + $header1 + " file1.csv")

This also works:

# The ini file has a single row
# field1,field2,field3,...
function Read_Headers_From_File($ini_file)
{   
    $temp = Get-Content $ini_file
    # return array of args for -Header 
    $temp.Split(",")
}

$header1 = Read_Headers_From_File("file1.ini")
$file1 = Import-Csv file1.csv -Header $header1
echo $file1

Sorry for the noise. If possible please delete the question.

edited Mar 12, 2016 at 10:35

answered Mar 12, 2016 at 9:12

Test User

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