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首页 > 解决方案 > 仅第一次使用 for 循环进行地理编码，并放入数据帧（在 R 中）

r - 仅第一次使用 for 循环进行地理编码，并放入数据帧（在 R 中）

问题描述

这是我需要帮助的时候，因为我已经尝试了一切来解决我的 FOR 循环的问题。我想使用 API 从地址进行地理编码，我使用了一个非常清晰的函数，以及更多的数据框来安排每个步骤的结果并检查是否存在问题，但现在我找不到更多...

地址：是我的带有地址列的数据框，结果将放在那里

"address_ID","address","accuracy","lon_geop","lat_geop","address_geop","geopID","success"
1,"4 Kiricheneck 9990"
2,"10 Kiricheneck 9990"
3,"26 Kiricheneck 9990""
4,"27 Kiricheneck 9990"
5,"6 Avenue D'oberkorn 4640"

编码：

plcUrl <- "https://apiv3.geoportail.lu/geocode/search?queryString="
getGeoDetails <- function(address)
{   
  query <- paste(addresses$address)
  strurl <- as.character(paste(plcUrl,query))
  rd <- fromJSON(URLencode(strurl))
  df <- data.frame(matrix(unlist(rd), nrow = 22, byrow = T),stringsAsFactors = FALSE)
  colnames(df)[1] <- "results_geop"  
answer <- data.frame(lat = NA, lon =  NA, accuray = NA, address_geop = NA, success = NA, geopID = NA)
answer$status <- df$results_geop[22]
#return Na's if we didn't get a match
  if (df$results_geop[22] != "TRUE")
  {
    return(answer)
  }   
#else, extract what we need from the GeoPortail server reply into a dataframe
answer$lat <- df$results_geop[9]
answer$lon <- df$results_geop[8]   
answer$accuracy <- df$results_geop[21]
answer$geopID <- df$results_geop[19]
answer$address_geop <- df$results_geop[6]
answer$success <- df$results_geop[22]
  return(answer)
}

#initialise a dataframe to hold the results
geocoded <- data.frame()
startindex <- 1
row_addresses <- as.numeric(rownames(addresses))

# Start the geocoding process - address by address
for (j in startindex:row_addresses)
{
#query the GeoPortail geocoder
  result = getGeoDetails(addresses[j]) 
  print(result$status)     
  result$index <- j
#append the answer to the results file
  geocoded <- rbind(geocoded, result)

#now we add all the results to the main data
addresses$lat_geop[j] <- geocoded$lat[j]
addresses$lon_geop[j] <- geocoded$lon[j]
addresses$accuracy[j] <- geocoded$accuracy[j]
addresses$address_geop[j] <- geocoded$address_geop[j]
addresses$geopID[j] <- geocoded$geopID[j]
addresses$success[j] <- geocoded$success[j]

return(j)}

最后： 警告信息：在 startindex:row_addresses 中：数值表达式有 5 个元素：仅使用第一个

并且addresses数据框只有第一行效果好，其他都是空的。我试过了：

  1. 索引：for(i in 1:x)
  2. 为结果和循环构建空数据框（索引 i）：d[i, ] = c(x, y, z)
  3. 中断命令
  4. 下一个命令

还没有任何帮助......我的其他 for 循环可以完成这项工作，所以这非常令人沮丧。

标签： rloopsfor-loopgeocoding

解决方案

让我们制作一些可用的数据：

data.frame(
  address_ID = 1:5, 
  address = c(
    "4 Kiricheneck 9990", "10 Kiricheneck 9990", 
    "26 Kiricheneck 9990", "27 Kiricheneck 9990",
    "6 Avenue D'oberkorn 4640"
  ),
  stringsAsFactors = FALSE
) -> xdf

现在，让我们为该端点制作一个适当的 API 包装器：

geoportail_geocode <- function(query) {

  suppressPackageStartupMessages({ # this makes it self-contained and quiet
    library(httr, warn.conflicts = FALSE, quietly = TRUE, verbose = FALSE)
    library(jsonlite, warn.conflicts = FALSE, quietly = TRUE, verbose = FALSE)
  })

  `%||%` <- function(x, y) { if (length(x)) x else y } # this makes the code below less 'if-else'y

  httr::GET(
    url  = "https://apiv3.geoportail.lu/geocode/search",
    httr::user_agent("geoportail_geocode R function used by me@example.com"), # you should add your email to this string
    query = list(
      queryString = query[1]
    )
  ) -> res

  httr::stop_for_status(res) # halts on API/network errors; you may not want this but it's standard practice in API packages

  out <- httr::content(res, as = "text", encoding = "UTF-8")
  out <- jsonlite::fromJSON(out)

  if (length(out$success) && out$success) { # if the return looks valid

    # MAKES A MAJOR ASSUMPTION A Point IS BEING RETURNED
    # YOU SHOULD DO A *TON* MORE VALIDATION AND ERROR CHECKING

    ret <- out$results[,c("ratio", "name", "easting", "address", "northing", "matching street", "accuracy")]
    ret <- cbind.data.frame(ret, out$results$AddressDetails)
    ret$type <- out$results$geomlonlat$type %||% NA_character_
    ret$lng <- out$results$geomlonlat$coordinates[[1]][1] %||% NA_real_
    ret$lat <- out$results$geomlonlat$coordinates[[1]][2] %||% NA_real_
    ret$geom <- out$results$geom$type %||% NA_character_
    ret$geom_x <- out$results$geom$coordinates[[1]][1] %||% NA_real_
    ret$geom_y <- out$results$geom$coordinates[[1]][2] %||% NA_real_

    ret

  } else {
    warning("Error in geocoding")
    data.frame(stringsAsFactors = FALSE)
  }

}

我们会做一个：

str(geoportail_geocode(xdf$address[1]))
## 'data.frame': 1 obs. of  19 variables:
##  $ ratio            : num 1
##  $ name             : chr "4,Kiricheneck 9990 Weiswampach"
##  $ easting          : num 73344
##  $ address          : chr "4 Kiricheneck,9990 Weiswampach"
##  $ northing         : num 133788
##  $ matching street  : chr "Kiricheneck"
##  $ accuracy         : int 8
##  $ zip              : chr "9990"
##  $ locality         : chr "Weiswampach"
##  $ id_caclr_street  : chr "8188"
##  $ street           : chr "Kiricheneck"
##  $ postnumber       : chr "4"
##  $ id_caclr_building: chr "181679"
##  $ type             : chr "Point"
##  $ lng              : num 6.08
##  $ lat              : num 50.1
##  $ geom             : chr "Point"
##  $ geom_x           : num 73344
##  $ geom_y           : num 133788

并使用tidyverse来完成所有操作并避免for像瘟疫 b/c 这样的循环，这不是 Java 或 icky Python：

str(dplyr::bind_cols(
  xdf,
  purrr::map_df(xdf$address, geoportail_geocode)
))
## 'data.frame': 5 obs. of  21 variables:
##  $ address_ID       : int  1 2 3 4 5
##  $ address          : chr  "4 Kiricheneck 9990" "10 Kiricheneck 9990" "26 Kiricheneck 9990" "27 Kiricheneck 9990" ...
##  $ ratio            : num  1 1 1 1 1
##  $ name             : chr  "4,Kiricheneck 9990 Weiswampach" "10,Kiricheneck 9990 Weiswampach" "26,Kiricheneck 9990 Weiswampach" "27,Kiricheneck 9990 Weiswampach" ...
##  $ easting          : num  73344 73280 73203 73241 60462
##  $ address1         : chr  "4 Kiricheneck,9990 Weiswampach" "10 Kiricheneck,9990 Weiswampach" "26 Kiricheneck,9990 Weiswampach" "27 Kiricheneck,9990 Weiswampach" ...
##  $ northing         : num  133788 133732 133622 133591 65234
##  $ matching street  : chr  "Kiricheneck" "Kiricheneck" "Kiricheneck" "Kiricheneck" ...
##  $ accuracy         : int  8 8 8 8 8
##  $ zip              : chr  "9990" "9990" "9990" "9990" ...
##  $ locality         : chr  "Weiswampach" "Weiswampach" "Weiswampach" "Weiswampach" ...
##  $ id_caclr_street  : chr  "8188" "8188" "8188" "8188" ...
##  $ street           : chr  "Kiricheneck" "Kiricheneck" "Kiricheneck" "Kiricheneck" ...
##  $ postnumber       : chr  "4" "10" "26" "27" ...
##  $ id_caclr_building: chr  "181679" "181752" "181672" "181668" ...
##  $ type             : chr  "Point" "Point" "Point" "Point" ...
##  $ lng              : num  6.08 6.07 6.07 6.07 5.9
##  $ lat              : num  50.1 50.1 50.1 50.1 49.5
##  $ geom             : chr  "Point" "Point" "Point" "Point" ...
##  $ geom_x           : num  73344 73280 73203 73241 60462
##  $ geom_y           : num  133788 133732 133622 133591 65234

如函数代码中所述，该stop_for_status调用将终止该函数，因此您可能希望warn_for_status检查响应的状态代码并返回一个空的data.frame(stringsAsFactors=FALSE).

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