chrisjb/rdistancematrix

Builds isochrones using either the google distance matrix API or the Mapbox API. Contains functions to fetch the population and employment (England and Wales) within the isochrone.

rdistancematrix's Issues

Datetime format on departing time

I do not have much experience on handling datatime data. However, my understanding is that as.POSIXct() will convert the time to unix time based on the time zone of the local computer (same as Sys.timezone()). Thus the output time in my computer is in CST (UTC+8), yet not local UK time (UTC+0) and the stop message looks misleading to me.

RDistanceMatrix/R/utils-isochrone.R

Lines 11 to 24 in fa208ae

	# enter departing in form: YYYY-MM-DD 08:00:00
	if(departing != F & !grepl('[0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2,}',departing)) {
	stop(paste0('departure time must either be set to FALSE or a time in the format YYYY-MM-DD HH:MM:SS. Note the time is local UK time.'))
	} else if(departing != F) {
	# if departure time is set, set it to a time in the future (later today or tomorrow depending on whether or not the time has already passed today.
	# has the entered time already passed today?
	if(Sys.time() > as.POSIXct(departing)) {
	stop(paste0('your departure time ', departing, 'is not in the future.'))
	} else {
	departure_time <- paste0('&departure_time=',as.character(as.numeric(as.POSIXct(departing))),'&traffic_model=', model)
	}
	} else if(departing == F) {
	departure_time <- ''
	}

Would it be better to require users to input the timezone? We could still, by default, assume the area of analysis is in the same time zone with the computer. (Would it also be better to use the lubridate package to handle time?)

departing_unix_time <- as.numeric(ymd_hms(departing, tz = Sys.timezone()))

departure_time <- paste0("&departure_time=", departing_unix_time , "&traffic_model=", model))

As a side note, instead of using grepl, strptime may be a better function to validate time input

Error in Distance Matrix Request URL

First of all, thanks for writing this package. I have been looking for scripts to generate isochrone maps with google map API for a long time.

When I tried to generate the isochrone polygon, the make_isochrone function fails. I checked the code and believe the error may be caused by the request URL to the google map Distance Matrix Service. Currently, it only allows 25 origins/destinations in a single request. (https://developers.google.com/maps/documentation/javascript/distancematrix)

But the request URL in distance_from_origins and distance_to_destinations is now requesting 100 points at one time. The functions return a list of NULL and thus make_isochrone fails to work. I am not sure why the line err <- httr::http_error(doc) does not throw an error though.

RDistanceMatrix/R/utils-isochrone.R

Lines 51 to 58 in 8aaf799

	for(i in 1:(lots)){
	origin_txt <- gsub(' ', "+", paste0(origin[(1+100*(i-1)):(100*i)][!is.na(origin[(1+100*(i-1)):(100*i)])],collapse='|'))
	if(origin_txt == ''){
	break
	}
	u <- dist_url(origin_txt,dest,mode,departing,model, api_key=api_key)

RDistanceMatrix/R/utils-isochrone.R

Lines 108 to 115 in 8aaf799

	for(i in 1:(lots)){
	# set up string for up to 100 destinations
	dest_txt <- gsub(' ',"+",paste0(dest[(1+100*(i-1)):(100*i)][!is.na(dest[(1+100*(i-1)):(100*i)])],collapse='|'))
	if(dest_txt == ''){
	break
	}
	u <- dist_url(origin,dest_txt,mode,departing,model,api_key=api_key)

I changed the value 100 to 25 in my local machine and the functions work.