从字符串中提取号码 [英] Extract numbers from String

问题描述

我要解析字符串，创建一个的 PathSegmentCollection 。该字符串由用逗号分隔的数字和/或（任何）空格（如换行，标签，等...），还有数字可以用科学记数法写。

I have to parse a String to create a PathSegmentCollection. The string is composed of numbers separated by comas and/or (any) whitespaces (like newline, tab, etc...), also the numbers can be written using scientific notation.

这是一个例子：9.63074,9.63074 -5.55708e-006 0,0 1477.78

和的要点是：P1（9.63074，9.63074），P2（-0,555708，0），P3（0，1477.78）

And the points are: P1(9.63074, 9.63074), P2(-0,555708, 0), P3(0, 1477.78)

要提取我用一个普通的前pression号：

To extract numbers I use a regular expression:

Dim RgxDouble As New Regex("[+-]?\b[0-9]+(\.[0-9]+)?(e[+-]?[0-9]+)?\b")
Dim Matches As MatchCollection = RgxDouble.Matches(.Value)
Dim PSegmentColl As New PathSegmentCollection
Dim PFigure As New PathFigure

With Matches

  If .Count < 2 OrElse .Count Mod 2 <> 0 Then Exit Sub

  PFigure.StartPoint = New Point(.Item(0).Value, .Item(1).Value)

  For i As UInteger = 2 To .Count - 1 Step 2
    Dim x As Double = .Item(i).Value, y As Double = .Item(i + 1).Value
    PSegmentColl.Add(New LineSegment With {.Point = New Point(x, y)})
  Next

End With

它的工作原理，但我必须解析约十万（或以上）的字符串，并以这种方式太慢。我想找到一个更有效的，而解决办法：大部分的数字写在科学记数法，如果你认为这是一个更好的办法，我没有问题，用写在C ++ / CLI使用C / C ++程序集的时代++没有管理$​​ C $ C或C＃不安全code。

It works, but I have to parse about a hundred thousand (or more) strings, and in this way is too slow. I want to find a more efficient solution whereas: most of the times the numbers are not written in scientific notation and, if you think that's a better way, I have no problem to use an assembly written in C++/CLI that use C/C++ not managed code, or C# unsafe code.

推荐答案

为什么你想解析的路径标记自己的语法？这是一个复杂的事情，也许是受到改变（至少扩展）的未来。 WPF可以为你做到这一点：的http：// msdn.microsoft.com/en-us/library/system.windows.media.geometry.parse.aspx ，所以最好是让框架的工作。

Why are you trying to parse the path markup syntax yourself? It's a complicated thing, and perhaps a subject to be changed (at least extended) in the future. WPF can do this for you: http://msdn.microsoft.com/en-us/library/system.windows.media.geometry.parse.aspx, so it's better to let the framework work.

编辑：
如果分析是瓶颈，您可以尝试解析自己。我会建议您尝试以下和检查，如果它的速度不够快：

If the parsing is your bottleneck, you can try to parse yourself. I would recommend trying the following and checking if it's fast enough:

char[] separators = new char[] { ' ', ',' }; // should be created only once
var parts = pattern.Split(separators, StringSplitOptions.RemoveEmptyEntries);
double firstInPair = 0.0;
for (int i = 0; i < parts.Length; i++ )
{
    double number = double.Parse(parts[i]);
    if (i % 2 == 0)
    {
        firstInPair = number;
        continue;
    }
    double secondInPair = number;
    // do whatever you want with the pair (firstInPair, secondInPair) ...
}

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