Returning first row of group

Question

I have a dataframe consisting of an ID, that is the same for each element in a group, two datetimes and the time interval between these two. One of the datetime

Answer 1

By reproducing the example data frame and testing it I found a way of getting the needed result:

1. Order data by relevant columns (ID, Start)

   ordered_data <- data[order(data$ID, data$Start),]

2. Find the first row for each new ID

   final <- ordered_data[!duplicated(ordered_data$ID),]