Question

我创建了以下功能

numberstocks <- function (x)
sapply (seq_along(x), function(i) {
    for (i in 1) {
    ifelse (x[i]==0,0,ifelse(x[i]==-1,100,ifelse(x[i]==1,0,0)))
    }
    for (i in 2:10){
    ifelse (x[i]==0, ifelse(is.numeric(numberstocks(x[i-1]))>-1,numberstocks(x[i-1]),0),ifelse(x[i]==0,0,ifelse(x[i]==-1,100,ifelse(x[i]==1,-1*is.numeric(numberstocks(x[i-1])),0))))
}
})

我的数据看起来像这样：

AAPL <- c(1,0,0,-1,0,1,0,0,0,-1)
MSFT <- c(0,0,0,1,0,-1,0,1,-1,0)

df <- data.frame (AAPL,MSFT)

我想将该功能应用于我的数据框

df.new <- as.data.frame (lapply(df,numberstocks))

所需的输出是：

AAPL.new <- (100,100,100,-100,0,100,100,100,100,-100)
MSFT.new <- (0,0,0,100,100,-100,0,100,-100,0)

然而，它说“0列和0行的数据框”，我不明白为什么。有人能够确定我做错了吗？

我是一名初学者，从Excel中的小样本大小转移到R中更大的样本大小。

提前谢谢

Answer 1

在一个匹配输入/输出的函数下面。基本上，它循环遍历数组的每个值，并从输入中派生新值。

AAPL <- c(1,0,0,-1,0,1,0,0,0,-1)
AAPL.new <- c(100,100,100,-100,0,100,100,100,100,-100)

foo <- function(x) {

    newValue <- 0

    for (i in 1:length(x)) {

        if (x[i] == -1) {
            newValue <- -100
        } else if (x[i] == 1) {
            newValue <- 100
        } else if (x[i] == 0 && newValue != 100) {
            newValue <- 0
        }

        x[i] <- newValue

    }

    return(x)

}

# check whether the results match
foo(AAPL) == AAPL.new

AAPL <- c(1,0,0,-1,0,1,0,0,0,-1)
MSFT <- c(0,0,0,1,0,-1,0,1,-1,0)
df <- data.frame (AAPL,MSFT)

# now use sapply to execute the function on every column
sapply(df, foo) 

MSFT.new <- c(0,0,0,100,100,-100,0,100,-100,0)
df.new <- data.frame(AAPL.new, MSFT.new)

# check whether the results match
as.data.frame(sapply(df, foo)) == df.new

编写一个依赖于自身先前值的函数

1 个答案: