Nested ifelse R function passed to sapply() to create new data.frame

Suppose we create a data.frame like this:

> hugs_per_day <- rnorm(10)
> hugs_per_day <- as.data.frame(hugs_per_day)
> hugs_per_day
   hugs_per_day
1  -2.500457495
2  -0.204545274
3  -0.955424927
4   0.320184701
5   1.822908001
6  -0.058679520
7  -0.276004919
8   0.175341993
9  -0.137404974
10  0.005096691

And we want to run a function on each day to return a value based on the results, something like this:

nested_ifelse <- function(x){

ifelse (x > 1,     mood <- "happy",
    ifelse(x < 0,  mood <- "sad", 
                  开发者_如何学Python mood <- "same as yesterday" ))

   return(mood)
}

The nested_ifelse() example does what I want and I'm sure sapply() is the correct R function to populate a new column with results from the function, but I just can't put the two together.

nested_ifelse should be like this:

nested_ifelse <- function(x){
  mood <- ifelse (x > 1,   "happy",
    ifelse(x < 0, "sad", 
    "same as yesterday" ))
  return(mood)
}

or more simply,

nested_ifelse <- function(x)
  ifelse (x > 1,   "happy",
  ifelse(x < 0, "sad", 
  "same as yesterday" ))

and you can use like this:

d$mood2 <- sapply(d$v, nested_ifelse)

but actually you don't need to call sapply here:

d$mood <- nested_ifelse(d$v)

is enough.

data d should be like this...

d <- data.frame(v=rnorm(10))

You didn't use set.seed so the example is not reproducible but this should give you the requested vector:

    hugs_per_day$mood <- c("sad","same as yesterday","happy" )[
              findInterval(  hugs_per_day$hugs_per_day, c(-Inf, 0, 1) ) ]
    hugs_per_day
       hugs_per_day              mood
    1     0.5747557 same as yesterday
    2    -1.0236557               sad
    3    -0.0151383               sad
    4    -0.9359486               sad
    5     1.1022975             happy
    6    -0.4755931               sad
    7    -0.7094400               sad
    8    -0.5012581               sad
    9    -1.6290935               sad
    10   -1.1676193               sad

I'm not sure if this will work for your actual problem, but I thought I would point out that you don't always need to nest ifelse functions. Sometimes you can use them sequentially, just make sure you get the order right so you don't over-write previous values.

set.seed(229)
hugs_per_day <- data.frame(hugs=rnorm(10))

hugs_per_day$mood <- "same as yesterday"
hugs_per_day$mood <- with(hugs_per_day, ifelse(hugs > 1, "happy", mood))
hugs_per_day$mood <- with(hugs_per_day, ifelse(hugs < 0, "sad", mood))