Question

I apologize if the title may not be clear.

With

df <- data.frame(profit = c(1, 1, 0, 0, 0, -1),
                 offerA = round(rnorm(6), 2), 
                 offerB = round(runif(6), 2), 
                 offerC = sample(1:6))

df
  profit offerA offerB offerC
1      1  -0.51   0.91      6
2      1  -0.03   0.75      4
3      0  -1.02   0.28      5
4      0   0.63   0.61      1
5      0   2.32   0.37      2
6     -1  -0.15   0.43      3

I need to add a field named bid depending on the value of profit under the following conditions:

with(df,
  if (profit > 0) {
    apply(cbind(offerA, offerB, offerC), 1, max)
  }
  else if (profit = 0) {
    apply(cbind(offerA, offerB, offerC), 1, mean)
  }
  else if (profit < 0) {
    apply(cbind(offerA, offerB, offerC), 1, min)
  }
)

In this example the new df will be:

df
  profit offerA offerB offerC   bid
1      1  -0.51   0.91      6     6
2      1  -0.03   0.75      4     4
3      0  -1.02   0.28      5  1.42
4      0   0.63   0.61      1  0.75
5      0   2.32   0.37      2  1.56
6     -1  -0.15   0.43      3 -0.15

Because the value of bid is computed by rows, I want to write a function addBid() so that I can use something like apply(df, 1, addBid) but I can’t think of a good way adding my conditions above into the function. I hope I’m clear with my question. Thanks!

Answer 1

Maybe this could be useful

bid <- function(x, ref, add=FALSE){
  ref <- match(ref,names(df))
  result <- ifelse(df[,ref]>0, apply(df[,-ref],1,max), 
         ifelse(df[,ref]==0, rowMeans(df[,-ref]),  apply(df[,-ref],1,min)) )
  if(add){
    result <- cbind(x, bid=result)
  }
  return(result)
}

Where x is your data.frame, ref is the reference variable (profit) and add is a logical indicating if you want bid as a vector (if add=FALSE) or your original data.frame with bid as a new column (if add=TRUE).

set.seed(001)
df <- data.frame(profit = c(1, 1, 0, 0, 0, -1),
                 offerA = round(rnorm(6), 2), 
                 offerB = round(runif(6), 2), 
                 offerC = sample(1:6))

> bid(df, ref='profit')  # returns a vector
[1]  3.000000  4.000000  1.643333  1.033333  1.016667 -0.820000
> bid(df, ref='profit', add=TRUE) # returns a data.frame = df + bid
  profit offerA offerB offerC       bid
1      1  -0.63   0.69      3  3.000000
2      1   0.18   0.38      4  4.000000
3      0  -0.84   0.77      5  1.643333
4      0   1.60   0.50      1  1.033333
5      0   0.33   0.72      2  1.016667
6     -1  -0.82   0.99      6 -0.820000