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Question

此问题已更新多次。

这是how to create data frames (not just one) at once in r的另一个问题。我真的不明白该错误信息。我有两个数据框：

> route1
                      X1                         X2                         X3
1 Balboa Park, san diego, ca    Coronado, san diego, ca  USS Midway, san diego, ca
2 Balboa Park, san diego, ca  USS Midway, san diego, ca    Coronado, san diego, ca
3    Coronado, san diego, ca Balboa Park, san diego, ca  USS Midway, san diego, ca
4    Coronado, san diego, ca  USS Midway, san diego, ca Balboa Park, san diego, ca
5  USS Midway, san diego, ca Balboa Park, san diego, ca    Coronado, san diego, ca
6  USS Midway, san diego, ca    Coronado, san diego, ca Balboa Park, san diego, ca

和

> place
# A tibble: 8 x 5
  name                                                hour type  short                abbr  
* <chr>                                              <dbl> <chr> <chr>                <chr> 
1 Balboa Park, san diego, ca                             4 place Balboa Park          bal   
2 USS Midway, san diego, ca                              2 place USS Midway           midway
3 Coronado, san diego, ca                                4 place Coronado             coro  
4 Cabrillo National Monument, san diego, ca              2 place Cabrillo             cab   
5 La Jolla Cove, san diego, ca                           2 place La Jolla             ljc   
6 4002 Wallace St, San Diego, CA 92110                   4 place Old Town             ot    
7 Hotel Republic San Diego, Autograph Collection        NA hotel Autograph Collection NA    
8 THE US GRANT, a Luxury Collection Hotel, San Diego    NA hotel Luxury Collection    NA

我的想法是使用ggmap包获取从Hotel Republic San Diego, Autograph Collection（place$name[7]）到route1第一行中第一位的行驶时间，然后从route1第一行的第一位到route1第一行的第二位，依此类推，直到route1第一行的最后一位到{{ 1}}（THE US GRANT, a Luxury Collection Hotel, San Diego）。汇总时间，存储在place$name[8]列中。然后对以下行执行相同的操作。所以我的代码是

route1$time

执行此代码可以给我

library(ggmap)
register_google(key = "my_google_key_here")
route1$time <- 0
for (i in 1:length(route1)) {
  for (j in 1:length(route1[i,])) {
    if(j == 1){
      route1$time[i] <- route1$time[i] + mapdist(from = place$name[7], to = as.character(route1[i,][1]))$seconds
    }
    if(j == length(route1[i,])){
        route1$time[i] <- route1$time[i] + mapdist(from = as.character(route1[i,][j]), to = place$name[8])$seconds
        route1$time[i] <- route1$time[i] + mapdist(from = as.character(route1[i,][j - 1]), to = as.character(route1[i,][j]))$seconds
    }
    for (j in 2:length(route1[i,]-1)) {
      route1$time[i] <- route1$time[i] + mapdist(from = as.character(route1[i,][j - 1]), to = as.character(route1[i,][j]))$seconds
    }
  }
}

错误消息，我认为这是我在数字中添加了一个字符，但找不到它。

Answer 1

# this is a nice library for R
library(tidyverse)

# name your variables
# (you can use these as arguments to a function or something)
start = place$name[7]
end = place$name[8]

# wrap your computation into a function which takes
# a row of a data frame as input    
compute_route_time = function(row) {
  # get a vector of stops that you can loop through
  stops = unlist(row)

  # distance from start to first stop
  time = mapdist(from = start, to = stops[1])$seconds
  # iterate through the rest of the route
  n_stops = length(stops)
  for (i in 1:(n_stops-1)) {
    time = time + mapdist(from = stops[i], to = stops[i+1])$seconds
  }
  # finish rout
  time = time + mapdist(from = stops[n_stops], to = end)$seconds

  # collect row as a data frame to preserve old columns
  row = as.data.frame(row)
  # add time column
  row$time = time
  return(row)
}

route1 %>%
  dplyr::rowwise() %>%
  dplyr::do(compute_route_time(.))

ggmap

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