Rilcon42 - 4 months ago 12

R Question

I am trying to get the column

`importantval`

`data<-data.frame(lower=c(1,4,6,7,7),upper=c(3,5,7,8,9),importantval=c(99,98,97,96,95))`

vals<-c(1.14,3.5,7.2,19)

> data

lower upper importantval

1 1 3 99

2 4 5 98

3 6 7 97

4 7 8 96

5 7 9 95

output goal

`# 1.14 99`

# 3.5 98

# 7.2 96 <--return the smalller interval (from 7 to 8 is smaller than 7 to 9)

# 19 NA <--doesnt exist so return NA

Answer

A simple `lapply`

would do the trick. Identifying the line is relatively easy. The if statement to take only the smaller interval when multiple values work is a bit harder to understand but mostly, if there are more than one possibility, I take the row where the interval is equal to the smallest interval possible.

```
foo <- function(i) {
res <- data[data$lower < i & data$upper > i, ]
if (nrow(res) > 1) {
res <- res[which(res$upper - res$lower == min(res$upper - res$lower)), ]
}
if (nrow(res) == 0) return(NA)
return(res$importantval)
}
results <- data.frame(vals, sapply(vals, foo))
```

This assumes that there are no intervals that are of same length. If this is a possibility, you could add `return(min(res$importantval))`

at the end to get only the smaller value.

If you would want to keep both values, take the results in a list:

```
results <- lapply(vals, foo)
names(results) <- vals
```