我得到3时，Mathematica Pick停止列表 [英] Mathematica Pick stop a list as soon as I get a 3

问题描述

这就是我所拥有的...

Here's what I have...

Select[roll, # <= 3 &]

现在，下面的列表可能有1个3或2个3.我希望它从左到右停在前三个.

Now, the list that follows may have one 3 or two three's. I want it to stop at the first three from left to right.

试图编码的数学家.

推荐答案

注意:我删除了原来的帖子，基本上与belisarius的帖子相同.这是另一种尝试...

Note: I removed my original posting, which was basically like that of belisarius. Here's another try...

如果您确定数字3是roll的成员，那么这应该起作用:

If you are sure that the number 3 is a member of roll then this should work:

TakeWhile[roll, # != 3 &]~Append~3

这等效于:

Take[roll, LengthWhile[roll, # != 3 &] +1]

如果您不能做出此假设，请先使用MemberQ

If you cannot make this assumption, just test first with MemberQ

编辑:感谢TomD在第二个解决方案中建议+1，从而消除了使用Append的需要.

EDIT: Credit goes to TomD for suggesting the +1 in the second solution, which eliminates the need to use Append.

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