如何在Google Geocode循环中跳过重复国家以减少API调用

Got it! Let's tweak your code to skip duplicate country names and save those valuable Google API calls. We'll add an if check plus a simple cache to store coordinates we've already fetched:

Modified Code #

register_google(key='your key')
t<-data.frame(importer_country=c("spain", "spain", "spain","united states","spain","eswatini", "spain", "spain", "spain", "spain", "spain", "spain", "spain"))
t$importer_country<-as.character(t$importer_country)

# Initialize latitude and longitude columns with NA to ensure consistent data types
t$importer_lon <- NA_real_
t$importer_lat <- NA_real_

# Create a cache to store coordinates for countries we've already processed
coord_cache <- list()

for(i in 1:nrow(t)){
  current_country <- t$importer_country[i]
  
  # Check if we already have coordinates for this country in the cache
  if(current_country %in% names(coord_cache)){
    # Reuse cached coordinates instead of calling the API again
    t$importer_lon[i] <- coord_cache[[current_country]]$lon
    t$importer_lat[i] <- coord_cache[[current_country]]$lat
  } else {
    # Only call the API for new, unprocessed countries
    result <- geocode(current_country, output = "latlon", source = "google")
    t$importer_lon[i] <- as.numeric(result$lon)
    t$importer_lat[i] <- as.numeric(result$lat)
    
    # Save the fetched coordinates to the cache for future use
    coord_cache[[current_country]] <- list(lon = t$importer_lon[i], lat = t$importer_lat[i])
  }
}

head(t)

Key Changes Explained #

• Pre-initialize Columns: We set up importer_lon and importer_lat with NA_real_ upfront to avoid unexpected data type issues later.
• Coordinate Cache: The coord_cache list acts as a temporary storage for already retrieved coordinates, mapped by country name. This cuts down API calls from 13 to just 3 (one per unique country).
• If Check Logic: Inside the loop, we first verify if the current country exists in our cache. If it does, we pull the stored coordinates; if not, we call the API and immediately save the result to the cache for future duplicates.

This approach keeps your script efficient, stays within Google's API limits, and ensures all duplicate rows get the correct coordinates without redundant calls.

内容的提问来源于stack exchange，提问作者Dr. Flow