我可能会猜测无效行的位置未知.在这种情况下，读取原始文件并创建仅包含有效数据的新文件可能是明智的.而且，如果源数据可以从操纵中受益，则可以在将其读入R之前完成.

I'd hazard a guess that the invalid row's location is not known. In such a case, it might be sensible to read the original file and create a new file that contains only valid data. What's more, if the source data would benefit of manipulation, it can be done before reading it into R.

一个大到3,5 GiB的文件在较大的方面有点要读入这样的内存中.当然，它可以在64位系统时代完成，但是对于简单的行处理而言，这并不方便.可伸缩的解决方案使用.Net方法和逐行方法.

A file as large as 3,5 GiB is a bit on the large side to read in memory as such. Sure, it can be done in the days of 64 bit systems, but for simple row processing it's unwieldy. A scalable solution uses .Net methods and row-by-row approach.

要逐行处理文件，请使用.Net方法进行有效的行读取.创建StringBuilder来存储包含有效数据的行，其他行则被丢弃. StringBuilder经常在磁盘上刷新.即使是几天的SSD，相对于一次写入大量(例如10000)行，每行的写入操作也相对较慢.

To process a file on row-by-row basis, use .Net methods for efficient row reading. A StringBuilder is created to store rows that contain valid data, others are discarded. The StringBuilder is flushed on disk every so often. Even on days of SSDs, a write operation for each row is relatively slow in respect to writing in a bulk of, say, 10 000 rows a time.

$sb = New-Object Text.StringBuilder
$reader = [IO.File]::OpenText("MyCsvFile.csv")
$i = 0
$MaxRows = 10000
$colonCount = 30
while($null -ne ($line = $reader.ReadLine())) {
    # Split the line on semicolons
    $elements = $line -split ';'
    # If there were $colonCount elements, add those to builder
    if($elements.count -eq $colonCount) {
        # If $line's contents need modifications, do it here
        # before adding it into the builder
        [void]$sb.AppendLine($line)
        ++$i
    }
    # Write builder contents into file every now and then
    if($i -ge $MaxRows) {
        add-content "MyCleanCsvFile.csv" $sb.ToString()
        [void]$sb.Clear()
        $i = 0
    }
}
# Flush the builder after the loop if there's data
if($sb.Length -gt 0) {
    add-content "MyCleanCsvFile.csv" $sb.ToString()
}