如何访问Import-Csv数组中的特定行? [英] How To Access Specific Rows in an Import-Csv Array?

问题描述

我需要将一个大文件上传拆分为多个并行进程，并希望使用单个CSV文件作为输入. 是否可以从Import-Csv对象访问行块，如下所示:

I need to split a large file upload into many parallel processes and want to use a single CSV file as input. Is it possible to access blocks of rows from an Import-Csv object, something like this:

$SODAData = Import-Csv $CSVPath -Delimiter "|" |
            Where $_.Rownum == 20,000..29,999 | 
            Foreach-Object { ... }

这种提取的语法是什么? 我正在使用Powershell 5.

What is the syntax for such an extraction? I'm using Powershell 5.

推荐答案

Import-Csv将文件作为对象数组导入，因此您可以执行以下操作(使用范围运算符):

Import-Csv imports the file as an array of objects, so you could do something like this (using the range operator):

$csv = Import-CSv $CSVPath -Delimiter '|'
$SOAData = $csv[20000..29999] | ForEach-Object { ... }

一种替代方法是使用Select-Object:

$offset = 20000
$count  = 10000
$csv = Import-Csv $CSVPath -Delimiter '|'
$SODAData = $csv |
            Select-Object -Skip $offset -First $count |
            ForEach-Object { ... }

如果要避免将整个文件读入内存，可以将以上内容更改为单个管道:

If you want to avoid reading the entire file into memory you can change the above to a single pipeline:

$offset = 20000
$count  = 10000
$SODAData = Import-Csv $CSVPath -Delimiter '|' |
            Select-Object -Skip $offset -First $count |
            ForEach-Object { ... }

但是请注意，使用这种方法需要多次读取文件才能处理多个数据块.

Beware, though, that with this approach you need to read the file multiple times for processing multiple chunks of data.

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