R：如何在第一列中查找值并在第三列中求和

Question

I have file like this

    Age.Range            Average  Probability
1    0 to 04               400     0.00400
2   05 to 09               221     0.00221
3   10 to 14               216     0.00216
4   15 to 19               409     0.00409

X [age of an individual; integer between 0 and 80 years]

Y [the duration of monitoring of an individual; integer between 1 and 50 years or “for life”]

I need to calculate probability that the person of age X (ex. 3) will develop cancer during the interval starting today until Y(ex. 7). In RI need to find value of X and value of X+Y in first column and sum all the values in the third column between those two ranges:

X= 3
x+y=10
probability= 0.004 + 0.00221 + 0.00216

Answer 1

The following function does what you want. It gets the starts of the age ranges and then uses findInterval to find the indices into the probabilities column. Then it is a matter of adding those probabilities.

sumProbs <- function(DF, X, Y){
  DF[["Age.Range"]] <- as.character(DF[["Age.Range"]])
  Age.Start <- strsplit(DF[["Age.Range"]], " to ")
  Age.Start <- as.integer(sapply(Age.Start, '[[', 1))
  i <- findInterval(c(X, X + Y), Age.Start)
  p <- DF[["Probability"]][i[1]:i[2]]
  sum(p)
}

sumProbs(df1, 3, 7)
#[1] 0.00837

Data in dput format.

df1 <-
structure(list(Age.Range = c("0 to 04", "05 to 09", 
"10 to 14", "15 to 19"), Average = c(400L, 221L, 
216L, 409L), Probability = c(0.004, 0.00221, 0.00216, 
0.00409)), row.names = c("1", "2", "3", "4"), 
class = "data.frame")