如果找不到地址,则继续循环

时间:2018-10-21 16:59:07

标签: r lapply ggmap

目标::我正在尝试使用get_map中的ggmaps函数检索一系列地图。

使用纬度和经度时,我知道以下作品:

houses_maps <- lapply(latlon,
                  function(x)
                    get_map(location = x,
                            zoom = 20, 
                            maptype = "satellite", 
                            source = "google")) 

问题:当我使用地址而不是纬度和经度时,它并没有完成循环。这可能是由于找不到地址之一,例如“ tomet,6-10,25720 Bellver de Cerdanya,Lleida,Spain”

我收到此错误:

Error in data.frame(ll.lat = ll[1], ll.lon = ll[2], ur.lat = ur[1], ur.lon = ur[2]) : 
  arguments imply differing number of rows: 0, 1
In addition: Warning message:
geocode failed with status ZERO_RESULTS, location = "tomet, 6-10, 25720 Bellver de Cerdanya, Lleida, Spain" 
Called from: data.frame(ll.lat = ll[1], ll.lon = ll[2], ur.lat = ur[1], ur.lon = ur[2])

问题::如何获取它忽略找不到的地址并将其保留为NA,然后继续搜索其余而不是停止。我有2,000个地址,很可能找不到几个地址。

2 个答案:

答案 0 :(得分:1)

由于我都没有示例数据(请始终在您的问题中提供数据),并且 也不知道我要演示的get_map函数的许多细节 只是这里的基本想法:

# simplified example data
latlon = c("address 1", "address 2", "address 3")

# mock the function
get_map <- function(location, ...) {
  if (location == "address 2") stop(paste("geocode failed with status ZERO_RESULTS, location =", location))
  return(location)
}


houses_maps <- lapply(latlon,
                      function(x)
                        tryCatch(get_map(location = x,
                                   zoom = 20, 
                                   maptype = "satellite", 
                                   source = "google"),
                                 error = function(e) {
                                   print(e)
                                   return(NA)
                                 }))
# <simpleError in get_map(location = x, zoom = 20, maptype = "satellite",
# source = "google"): geocode failed with status ZERO_RESULTS,
# location = address 2>    

houses_maps                      
# [[1]]
# [1] "address 1"
# 
# [[2]]
# [1] NA
# 
# [[3]]
# [1] "address 3"

答案 1 :(得分:1)

使用try命令预先实际测试该功能。在您的示例中,应为:

houses_maps <- lapply(latlon,
                  function(x)
                  res <- try(get_map(location = x,
                            zoom = 20, 
                            maptype = "satellite", 
                            source = "google"))
                  if(inherits(res, "try-error")) next
                  else{
                    get_map(location = x,
                            zoom = 20, 
                            maptype = "satellite", 
                            source = "google")}
                  )

我本人无法对此进行测试,因此希望我将所有括号都关闭了,但是您明白了它的要旨。