Null check for departure_datetime parameter

[mattwigway]

If you feed a NULL departure_datetime parameter to travel_time_matrix, it crashes with the message "java.lang.NullPointerException" and no other details. It would be great to have a null check for this parameter.

[rafapereirabr]

Thanks for the heads up. As it stands, the routing functions in r5r set departure_datetime = Sys.time() by default. Nonetheles, the functions were throwing an error because the time zone information was missing. I've fixed this so that r5r now considers the user's time zone by default. See reprex below.

As an alternative, the user can set a different time zone using: as.POSIXct("13-05-2019 14:00:00", format = "%d-%m-%Y %H:%M:%S", tz="UTC")

Reprex:

library(r5r)

# build transport network and load origin/destination points
data_path <- system.file("extdata/spo", package = "r5r")
r5r_core <- setup_r5(data_path = data_path)
points <- read.csv(file.path(data_path, "spo_hexgrid.csv"))[1:5,]

ttm <- travel_time_matrix(r5r_core,
                   origins = points,
                   destinations = points,
                   mode = c("WALK"),
                   max_walk_dist = Inf,
                   max_trip_duration = 120L)

[mattwigway]

Wouldn't it be better to use the transport network's time zone? Otherwise results from identical code could change depending on where the user is.