不支持的SEXPTYPE：19

Question

我试图使用R提取行程时间和两点之间的距离，但出于某种原因，我有以下错误。

library(ggmap)
list <-  mapdist("Hamilton, ontraio, Canada", "Toronto, Ontario, Canada",mode="driving") 
res <- list$hour

我遇到的错误

ist <- mapdist("Hamilton, ontraio, Canada", "Toronto, Ontario, Canada",mode="driving")
by using this function you are agreeing to the terms at :
http://code.google.com/apis/maps/documentation/distancematrix/


unsupported SEXPTYPE: 19
Information from URL : http://maps.googleapis.com/maps/api/distancematrix/json?origins=Hamilton+ontraio+Canada&destinations=Toronto+Ontario+Canada&mode=driving&sensor=false
Error in `*tmp*`[[c(1, 1)]] : subscript out of bounds

关于如何解决它的任何想法?????