Find the first moment that a column meets a condition in R-CodePudding

I need to find the number of the row that data in the columns reached a certain value.

Data:

Data = data.frame(    Time = seq(1,5),
                    V1 = c(0.1, 0.2, 0.4, 0.7, 0.9),
                    v2 = c(0.1, 0.12, 0.41, 0.72, 0.91),
                    v3 = c(0.03, 0.13, 0.62, 0.50, 0.90))

Desired result: (First Time In 0.6)

  V1 V2 V3
1  4  4  3

CodePudding user response：

We can use dplyr with summarise and first(which(condition))

library(dplyr)

Data %>% summarise(across(-Time, ~first(which(.x>0.6))))

  V1 v2 v3
1  4  4  3

Or with base R:

data.frame(lapply(Data[-1], \(x) first(which(x>0.6))))

CodePudding user response：

Using base R:

Use which to find the indices of rows that satisfy your condition and min to find the lowest (i.e., first) of these indices. Also use lapply to apply it multiple columns like so:

data.frame(lapply(Data[c("V1", "v2", "v3")], function(x) min(which(x > 0.6))))