How to find the given value from the range of values? - r

Question

I have have the below data :
Y z
100-800 a
150-600 b
200-300 c
400-600 d
4000-12000 e
Any help would be really appreciated.
Based on given value of x (i.e x=100) it should find the values in the given ranges of Y and give the corresponding values of Y and z.If the given of x is not in the given ranges of Y then it should find the nearer range and give corresponding values of Y and Z.
DT[, list(OK = 1 %in% seq(Y, Y)), by = Z]
For given value of X=110
output should be
Y Z
100-800 a
For x=200
Y z
100-800 a
150-600 b
200-300 c
For x=12500
Y z
4000-12000 e

Answer 1

We can write a helper function using tidyr::separate to separate columns. In case if there are no indices which fall within the range we compare the value with lowest value and highest value in the dataframe and return the row accordingly.
subset_fun <- function(df, val) {
df1 <- tidyr::separate(df, Y, c("low", "high"), sep = "-",convert = TRUE)
inds <- with(df1, val >= low & val <= high)
if (any(inds))
df[inds, ]
else if (min(df1$low) > val) df[which.min(df1$low), ]
else df[which.max(df1$high), ]
}
subset_fun(df, 100)
# Y z
#1 100-800 a
subset_fun(df, 200)
# Y z
#1 100-800 a
#2 150-600 b
#3 200-300 c
subset_fun(df, 12500)
# Y z
#5 4000-12000 e
subset_fun(df, 0)
# Y z
#1 100-800 a
data
df <- structure(list(Y = structure(1:5, .Label = c("100-800", "150-600",
"200-300", "400-600", "4000-12000"), class = "factor"),
z = structure(1:5, .Label = c("a", "b", "c", "d", "e"), class = "factor")),
class = "data.frame", row.names = c(NA, -5L))

Answer 2

We can create a helper and use this to subset:
library(dplyr)
library(tidyr)
find_number <- function(x,high,low){
x >= low & x < high # might be able to use between
}
df %>%
separate(Y,c("Low","High")) -> new_df
new_df[new_df %>%
mutate(Logi=find_number(200,high = High,low=Low)) %>%
pull("Logi"),]
Low High z
1 100 800 a
2 150 600 b
3 200 300 c
EDIT: An attempt to automate this process. Using NSE might be a much better option since that would eliminate the need to have the exact same names as in this answer. In other words, redefine the function with a data and column name arguments. For now:
find_number <- function(x){
new_df[new_df %>%
mutate(Logi=x >= Low & x< High,
isMax=ifelse(High==max(High)
& x>High,
TRUE,Logi)) %>%
pull("isMax"),]
}
find_number(12500)
Low High z
5 4000 12000 e
Data:
new_df<-structure(list(Low = c(100, 150, 200, 400, 4000), High = c(800,
600, 300, 600, 12000), z = c("a", "b", "c", "d", "e")), class = "data.frame", row.names = c(NA,
-5L))