Question

Here is a subset of my data:

Fr         Sig  Code NumDet    Date.Time          Aerial
62  150102 102   15    195 2012-09-14 18:28:00      1
63  150102 102   15    189 2012-09-14 18:32:00      1
64  150102 106   15    213 2012-09-14 18:36:00      1
65  150102 102   15    152 2012-09-14 18:40:00      1
66  150102 105   15    190 2012-09-14 18:46:00      1
67  150102  97   15      4 2012-09-14 18:51:00      2

I am trying to calculate time between first detection on Aerial 1 and first detection on Aerial 2. Hence in this data set it would be 23mins

I have tried variations of difftime but can’t seem to select specific times based on the Aerial number.

I have tried:

a <- difftime(table$Date.Time[2:length(table$Aerial == "1")], 
              table$Date.Time[2:length(table$Aerial == "2")])

but it’s not even close.

Answer 1

This command using difftime

difftime(table$Date.Time[table$Aerial == "2"][1],
         table$Date.Time[table$Aerial == "1"][1])

will return

Time difference of 23 mins