批处理文件：从 .csv 文件中读取浮点值

Question

我制作了一个读取 .csv 文件的批处理文件。然后它继续从特定列（在本例中为第 4 列）中获取值并找到最高值。该脚本可以很好地处理整数，但是一旦我尝试传入具有浮点数的 .csv 文件，该脚本只会读取第一个数字。即，1.546 = 1、0.896 = 0 等...

如何正常读取浮点数？在这种情况下，至少有 2 个精度点（尽管使用真实 .csv 文件的值可以达到 6 个精度点）

要注意的另一件事是，这会打印出 3 次“缺少运算符”。我认为这可能是由于间距，但不确定在哪里。

脚本如下：

@echo off

set cur=0
set max=0

for /f "usebackq tokens=1-4 delims=," %%a in ("sample.csv") do (call :func "%%d")
echo Max is %max%
goto :here

:func
 set /a cur=%1
 if %cur% gtr %max% (set /a max=%cur%)
 goto :eof

:here

pause

这是 sample.csv，可以正常工作：

1,2,,3,3,5,,
5,6,,7,12.3,6,,
9,10,,11,11.4,7,,
13,14,,15,10.1,2,,

我添加了一些额外的逗号，只是为了测试代码。

Answer 1

如果您要进行实际计算，那么在使用分数时我不建议使用batch-file，而是为了简单地测试最高值，我们可以通过. 匹配任一侧来分割字符串。不过，您仍然不能使用 set /a 使其成为实际整数：

@echo off & setlocal enabledelayedexpansion
set num=0 & set frac=0 
for /f "usebackq tokens=1-4 delims=," %%a in ("sample.csv") do (
  for /f "tokens=1* delims=." %%i in ("%%~d") do (
      if not "%%j" == "" if %%i gtr !num! (
         set "num=%%i"
         set "max=%%~d"
  )
      if %%i geq !num! if %%~j gtr !frac! (
         set "frac=%%~j"
         set "max=%%~d"
    )
  )
)
echo Max is %max%
pause

根据您对~ 的评论，这里是for /? 的摘录

In addition, substitution of FOR variable references has been enhanced.
You can now use the following optional syntax:

    %~I         - expands %I removing any surrounding quotes (")
    %~fI        - expands %I to a fully qualified path name
    %~dI        - expands %I to a drive letter only
    %~pI        - expands %I to a path only
    %~nI        - expands %I to a file name only
    %~xI        - expands %I to a file extension only
    %~sI        - expanded path contains short names only
    %~aI        - expands %I to file attributes of file
    %~tI        - expands %I to date/time of file
    %~zI        - expands %I to size of file
    %~$PATH:I   - searches the directories listed in the PATH
                   environment variable and expands %I to the
                   fully qualified name of the first one found.
                   If the environment variable name is not
                   defined or the file is not found by the
                   search, then this modifier expands to the
                   empty string

The modifiers can be combined to get compound results:

    %~dpI       - expands %I to a drive letter and path only
    %~nxI       - expands %I to a file name and extension only
    %~fsI       - expands %I to a full path name with short names only
    %~dp$PATH:I - searches the directories listed in the PATH
                   environment variable for %I and expands to the
                   drive letter and path of the first one found.
    %~ftzaI     - expands %I to a DIR like output line

In the above examples %I and PATH can be replaced by other valid
values.  The %~ syntax is terminated by a valid FOR variable name.
Picking upper case variable names like %I makes it more readable and
avoids confusion with the modifiers, which are not case sensitive.

Answer 2

正如 cmets 中提到的，您可以使用 powershell 来完成此任务。这是一个基本的想法。

示例文件内容：

1,2,,3,3,5,,
5,6,,7,12.3,6,,
9,10,,11,11.4,7,,
13,14,,15,10.1,2,,

你可以使用类似的东西：

Import-Csv -Path ".\sample.csv" -Header ("A","B","C","D","E") | Sort-Object { [Single]$_.E } -Descending | Select-Object -First 1 -ExpandProperty E

应该返回：

12.3

正如你在上面看到的，因为你没有提供标题记录，我不得不创建一些来识别我的目标字段。但是，如果您已经知道标头字段，则可以稍微简化代码。

示例文件内容：

This,Is,My,Actual,Header,Record,,
1,2,,3,3,5,,
5,6,,7,12.3,6,,
9,10,,11,11.4,7,,
13,14,,15,10.1,2,,

您只需根据其标题值名称命名您的字段，例如：

Import-Csv -Path ".\sample.csv" | Sort-Object { [Single]$_.Header } -Descending | Select-Object -First 1 -ExpandProperty Header

应该再次返回：

12.3