CODEWITHSUNDEEP
rggmap
1053Inator
1053Inator

Reputation: 322

Using route function on multiple addresses in ggmap

I would like to calculate the route between multiple addresses using the route function in ggmap. I came up with 2 alternative solutions, but both don't work:

*alternative 1

First I made 2 vectors: one with points of interest (4 in total) and another one with the base address.

points_of_interest <- c(
"berlin",
"paris",
"new york",
"madrid")

base_address <- "helsinki"

The following should calculate the exact route between each pair of points_of_interest and base_address. So a total of 4 routes: berlin - helsinki, paris - helsinki, new york - helsinki and madrid - helsinki.

calculatedroutes1 <- route(from = base_address,
                          to = points_of_interest)

The problem is I only get the route for berlin-helsinki, although I thought it should be vectorized.

*alternative 2

Since route didn't seem to vectorize I thought maybe I could use plyr. So this was my alternative code:

 df.routes <- data.frame(points_of_interest,
                         rep(base_address, each = length(points_of_interest),
                         stringsAsFactors = FALSE)

 df. calculatedroutes2 <- ddply(.data = df.routes,
                           .variables = .(points_of_interest, base_address),
                           .fun = route,
                           points_of_interest,
                           base_address)

For each combination of points_of_interest and base_address (so for all 4 routes) I wanted to use the function route with arguments from = points_of_interest and to = base_address. This generated the error Error: unexpected ',' in "points_of_interest, but I think this is the right way to add arguments to a function in ddply?

Another question which is similar to mine other error route function is still unanswered.

Upvotes: 2

Views: 1181

Answers (2)

Pelayo
Pelayo

Reputation: 11

This generated the error Error: unexpected ',' in "points_of_interest, but I think this is the right way to add arguments to a function in ddply?

I guess you should put those arguments between quotes:

df. calculatedroutes2 <- ddply(.data = df.routes,
                       .variables = .(points_of_interest, base_address),
                       .fun = route,
                       "points_of_interest",
                       "base_address")

Upvotes: 1

jlhoward
jlhoward

Reputation: 59345

Looking at the code for route(...) (just type "route" at the command line, no ? or ()), this function is not vectorized, although the documentation suggests it is.

route(...) uses the Google Directions API, which takes a single origin and a single destination. If you pass a vector in the to=... argument, route(...) creates a vector of urls, but only uses the first one.

One way around this uses the Vectorize(...) function in R:

rt <- Vectorize(route,vectorize.args=c("from","to"),SIMPLIFY=FALSE)
rt(base_address,points_of_interest)

This, too will fail with your definitions for points_of_interest, because Google Directions supports three mode of transport: driving, bicycle, and walk, and none of these will get you from Helsinki to NY. If you remove new york from points of interest, you get a list of data frames with the routes from Helsinki to each of the other cities.

Upvotes: 2

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