?sample看看就可以了

谢谢，我先看看

Usage（用法）

sample(x, size, replace = FALSE, prob = NULL)
sample.int(n, size = n, replace = FALSE, prob = NULL)
看不懂啊，ind <- sample(2, nrow(iris), replace=TRUE, prob=c(0.7, 0.3))中2代表啥意思呢？

The first argument  "2" means "1" and "2". The second argument is the size of the sample you want create. In this case, it's the number of rows, nrow(iris). The third argument is "replace = T" allowing for replacement; choose "1" and put it back. The fourth argument define the probability for the frequency of "1" and "2"; "1" appears 70% of the time and "2" 30%. The second line of the code use "ind" to split the data into "training" and "test" data using the Learning terminology.

ind <- sample(2, nrow(iris), replace=TRUE, prob=c(0.7, 0.3))
>trainData <- iris[ind==1,]
>testData <- iris[ind==2,]
>nrow(trainData)
[1] 109
> nrow(testData)
[1] 41
109:41不等于0.7:0.3，咋回事？