如何使用 R 获取城市列表的每日天气预报？

Question

我尝试使用此函数获取日期框架，但无法正确获取，因为我正在尝试编写一个函数来返回包含城市列表的 5 天天气预报的数据框，但我不知道缺少什么。这里我使用 openweathermap.org 来获取天气数据。 谢谢。

# Get forecast data for a given city list
get_weather_forecaset_by_cities <- function(city_names){
    df <- data.frame()
    for (city_name in city_names){
        # Forecast API URL
        forecast_url <- 'https://api.openweathermap.org/data/2.5/forecast'
        # Create query parameters
        forecast_query <- list(q = city_name, appid = "b0847c4a1554d3c63d46d0e9249500f0", units="metric")
        # Make HTTP GET call for the given city
        responce<- GET(forecast_url, query= forecast_query)
        json_result <- content(responce, as="parsed")
        
        # Note that the 5-day forecast JSON result is a list of lists. You can print the reponse to check the results
         result <- json_result
        
        # Loop the json result
        for(result in results) {
            city <- c(city, city_name)
            
        }
        
        # Add the R Lists into a data frame
         # $weather is also a list with one element, its $main element indicates the weather status such as clear or rain
city  <- c(result$city$name)       
weather <- c( result$weather[[1]]$main)
# Get Visibility
visibility <- c( result$visibility)
# Get current temperature 
temp <- c(result$main$temp)
# Get min temperature 
temp_min <- c( result$main$temp_min)
# Get max temperature 
temp_max <- c( result$main$temp_max)
# Get pressure
pressure <- c( result$main$pressure)
# Get humidity
humidity <- c(result$main$humidity)
# Get wind speed
wind_speed <- c( result$wind$speed)
# Get wind direction
wind_deg <- c( result$wind$deg)
weather_data_frame <- data.frame(city,
                                 weather,
                                 visibility, 
                                 temp, 
                                 temp_min, 
                                 temp_max, 
                                 pressure, 
                                 humidity, 
                                 wind_speed, 
                                 wind_deg)

    }
    
    # Return a data frame
    return(df)
    
}

cities <- c("Seoul", "Washington, D.C.", "Paris", "Suzhou")
cities_weather_df <- get_weather_forecaset_by_cities(cities)

Answer 1

library(httr)
library(dplyr)
library(stringr)
library(jsonlite)
> city_names <- c("Seoul", "Washington, D.C.", "Paris", "Suzhou")
> api_id<-'b0847c4a1554d3c63d46d0e9249500f0'
> main_df<-data.frame()
> for (city_name in city_names){
>   url<-str_glue("http://api.openweathermap.org/data/2.5/forecast?id=524901&appid={api_id}&q={city_name}")
>   main_df<- bind_rows(main_df,get_weather_forecaset_by_cities(url))
> }
> 
> 
> get_weather_forecaset_by_cities <- function(url){
>   web_content <- httr::GET(url)
>   web_content <- content(web_content,"text")
>   json_data <- fromJSON(web_content, flatten = TRUE)
>   df <- as.data.frame(json_data)
>   return(df)
> }

Answer 2

我经过长时间的多次尝试终于能够做到了，这是完整的代码，你只需要添加你的API Key

# Get forecast data for a given city list
get_weather_forecaset_by_cities <- function(city_names) {
  df <- data.frame()
  for (city_name in city_names) {
    # Forecast API URL
    forecast_url <- "https://api.openweathermap.org/data/2.5/forecast"
    # Create query parameters
    forecast_query <- list(q = city_name, appid = "***API Key***", units = "metric")
    # Make HTTP GET call for the given city
    forecast_response <- GET(forecast_url, query = forecast_query)
    # Note that the 5-day forecast JSON result is a list of lists. You can print the response to check the results
    forecast_json_list <- content(forecast_response, as = "parsed")
    results <- forecast_json_list$list
    result <- c(1:40)

    # Loop the json result
    for (x in result) {
      city <- c(city, city_name)
      # $weather is also a list with one element, its $main element indicates the weather status such as clear or rain
      weather <- c(weather, results[[x]]$weather[[1]]$main)
      # Get Visibility
      visibility <- c(visibility, results[[x]]$visibility)
      # Get current temperature
      temp <- c(temp, results[[x]]$main$temp)
      # Get min temperature
      temp_min <- c(temp_min, results[[x]]$main$temp_min)
      # Get max temperature
      temp_max <- c(temp_max, results[[x]]$main$temp_max)
      # Get pressure
      pressure <- c(pressure, results[[x]]$main$pressure)
      # Get humidity
      humidity <- c(humidity, results[[x]]$main$humidity)
      # Get wind speed
      wind_speed <- c(wind_speed, results[[x]]$wind$speed)
      # Get wind direction
      wind_deg <- c(wind_deg, results[[x]]$wind$deg)
      # Get forcast_datetime
      forecast_datetime <- c(forecast_datetime, results[[x]]$dt_txt)
    }

    # Add the R Lists into a data frame
    df <- data.frame(
      city = city, weather = weather,
      visibility = visibility,
      temp = temp,
      temp_min = temp_min,
      temp_max = temp_max,
      pressure = pressure,
      humidity = humidity,
      wind_speed = wind_speed,
      wind_deg = wind_deg,
      forecast_datetime
    )
  }

  # Return a data frame
  return(df)
}