如何在PowerShell中对对象中的多个项目求和? [英] How to sum multiple items in an object in PowerShell?

问题描述

我有:

$report.gettype().name
Object[]

echo $report

Item                       Average
--                         -------
orange                     0.294117647058824
orange                    -0.901960784313726
orange                    -0.901960784313726
grape                      9.91335740072202
grape                      0
pear                       3.48736462093863
pear                      -0.0324909747292419
pear                      -0.0324909747292419
apple                     12.1261261261261
apple                     -0.0045045045045045

我想创建一个变量 $total(例如哈希表)，其中包含每个项目的Average"列的总和，例如，

I want to create a variable, $total, (such as a hash table) which contains the sum of the 'Average' column for each item, for example,

echo $total

orange  -1.5097
grape    9.913
pear     3.423
apple   12.116

现在我正在考虑遍历 $report，但它太丑了，我正在寻找比以下起点更优雅的东西(不完整):

Right now I'm thinking of looping through the $report, but it's hell ugly, and I am looking for something more elegant than the following starting point (incomplete):

$tmpPrev = ""
foreach($r in $report){
    $tmp = $r.item
    $subtotal = 0
    if($tmp <> $tmpPrev){
        $subtotal += $r.average
    }

我怎么能这样做?

推荐答案

Cmdlets Group-Object 和 Measure-Object 有助于以 PowerShell-ish 方式解决任务:

Cmdlets Group-Object and Measure-Object help to solve the task in a PowerShell-ish way:

代码:

# Demo input
$report = @(
    New-Object psobject -Property @{ Item = 'orange'; Average = 1 }
    New-Object psobject -Property @{ Item = 'orange'; Average = 2 }
    New-Object psobject -Property @{ Item = 'grape'; Average = 3 }
    New-Object psobject -Property @{ Item = 'grape'; Average = 4 }
)

# Process: group by 'Item' then sum 'Average' for each group
# and create output objects on the fly
$report | Group-Object Item | %{
    New-Object psobject -Property @{
        Item = $_.Name
        Sum = ($_.Group | Measure-Object Average -Sum).Sum
    }
}

输出:

Sum Item
--- ----
  3 orange
  7 grape

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