Question

什么是连续数字检测n模式最有效的方法？也许是一个SQL列或向量，R。一些伪代码-R-来说明“问题”：

find Pattern in consecutive integers, where 
2nd integer < 1st integer, 
3rd integer > 2nd integer & 
4th integer > 3rd integer.


a <- x
b <- x +1 < a
c <- x +2 > b
d <- x +3 > c

pattern <- c(a, b, c, d)
example: pattern <- c(10, 8, 9, 11) or pattern <- c(2.11, 2.08, 2.09, 2.11)

count(pattern)
find(pattern)

Answer 1

如果你取矢量的差值，那么第一个应该是负数而另外两个是正数，所以，

a <- c(10, 8, 9, 11)

all((diff(a) < 0) == c(TRUE, FALSE, FALSE))
#[1] TRUE

要将其应用于更大的向量，您可以使用rollapply包中的zoo，即

library(zoo)

a <- sample(1:100,100,replace=T)
unique(rollapply(a, 4, by = 1, function(i) i[all((diff(i) < 0) == c(TRUE, FALSE, FALSE))]))

给出，

      [,1] [,2] [,3] [,4]
 [1,]   85   18   85   92
 [2,]   44   27   67   76
 [3,]   58    2   39   54
 [4,]   85   69   82   84
 [5,]   61    4   40   44
 [6,]   65   58   73   97
 [7,]   19    9   92   96
 [8,]   33   24   57   73
 [9,]   79   11   37  100

以连续数字查找模式

1 个答案: