How can I count the number of rows in a csv file using powershell? I tried something like
Get-Content -length "C:\Directory\file.csv"
or
(Get-Content).length "C:\Directory\file.csv"
but these result an error.
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6 Answers
Get-Content and Measure-Object are fine for small files, but both are super inefficient with memory. I had real problems with large files.
When counting rows in a 1GB file using either method, Powershell gobbled up all available memory on the server (8GB), then started paging to disk. I left it over an hour, but it was still paging to disk so I killed it.
The best method I found for large files is to use IO.StreamReader to load the file from disk and count each row using a variable. This keeps memory usage down to a very reasonable 25MB and is much, much quicker, taking around 30 seconds to count rows in a 1GB file or a couple of minutes for a 6GB file. It never eats up unreasonable amounts of RAM, no matter how large your file is:
[int]$LinesInFile = 0
$reader = New-Object IO.StreamReader 'c:\filename.csv'
while($reader.ReadLine() -ne $null){ $LinesInFile++ }
The above snippet can be inserted wherever you would use get-content or measure-object, simply refer to the $LinesInFile variable to get the row count of the file.
8 Comments
alextc
Faster than any other solutions shown here. Less than 5 seconds to sort out a 500mb csv file.
Oleh Nechytailo
You also should dispose reader ($reader.Dispose()) after use or you risk holding file opened until you close your PS session.
Matt M
If using powershell add "write-output $LinesInFile" at end of block above to get the value on screen.
Nicholas Humphrey
just add
$LinesInFile at the end and you will see the number.
Geoff Griswald
@Linga Search for powershell scripts that process lists of files in a loop, insert my snippet inside the loop and specify the file name as a variable inside your loop.
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Pipe it to the Measure-Object cmdlet
Import-Csv C:\Directory\file.csv | Measure-Object
3 Comments
jrara
Thanks, this seems to work, but it is terribly slow compared e.g. to GNU Unix utils wc.exe.
EBGreen
That is because wc.exe would be the equivalent of (Get-Content).Length which while it is much faster than Import-CSV, it is also a potentially incorrect solution as pointed out by stej since it would not account for rows with multiline fields.
Franck Dernoncourt
(took ~1 minute for a 100 MB file)
Generally (csv or not)
@(Get-Content c:\file.csv).Length
If the file has only one line, then, it will fail. (You need the @ prefix...otherwise if the file has one line, it will only count the number of characters in that line.
Get-Content c:\file.csv | Measure-Object -line
But both will fail if any record takes more than one row. Then better import csv and measure:
Import-Csv c:\file.csv | Measure-Object | Select-Object -expand count
6 Comments
jrara
Last one seems to generate an error: Select-Object : Cannot expand property "count" because it has nothing to expand. At line:1 char:64 + Import-Csv C:\Directory\file.csv | Measure-Object | Select-Object <<<< -expand count
stej
Weird,
Measure-Object should return an object that has a property Count. Try to remove the |Select-Object ... and you will see what it returns.
Shay Levy
You're probably using PowerShell v1. In v1, 'Select-Object -expand propertyName' throws an error when the result is a scalar (one object). Upgrade to v2 and you're good to go.
jrara
Thanks, Yes, I'm using version 1.0, it's one of the tags of this question.
stej
I check only PowerShell tag. And silently assumed that nobody uses v1.0. Sorry :)
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You can simply use unix like comand in powershell.
If you file test.csv Then command to get rowcount is
gc test.csv | Measure-Object
Comments
You can try
(Import-Csv C:\Directory\file.csv).count
or
$a=Import-Csv C:\Directory\file.csv
$a.count
1 Comment
oɔɯǝɹ
I get an
OutOfMemoryException using this approach on a large file. Using Get-Content | Measure-Object works with a limited amount of memory..(Import-Csv C:\Directory\file.csv).count is the only accurate one out of these.
I tried all of the other suggestions on a csv with 4781 rows, and all but this one returned 4803.
