如何在gmapsdistance R包中传入多个出发日期与时间参数？

Hey there! You’re spot-on with your hunch — the dep_date and dep_time parameters in gmapsdistance don’t support vector inputs, which is exactly why you’re hitting that XML format error. When you pass vectors for these arguments, the package generates a malformed request that Google’s Distance Matrix API can’t parse, leading to the "XML declaration allowed only at the start..." message you’re seeing.

Here’s how to fix this:

1. Loop Through Each Date/Time Pair #

Since vector inputs aren’t supported, we’ll process each origin-destination-date-time combination one at a time using a loop, then combine the results. Here’s a working example:

# Make sure all your vectors are the same length first
stopifnot(length(origin_vector) == length(destination_vector),
          length(date_vector) == length(time_vector))

# Use lapply to iterate over each index
result_list <- lapply(seq_along(origin_vector), function(i) {
  gmapsdistance(
    origin = origin_vector[i],
    destination = destination_vector[i],
    combinations = "pairwise",
    mode = "driving",
    shape = "long",
    dep_date = date_vector[i],
    dep_time = time_vector[i]
  )
})

# Combine the results into a single data frame (adjust based on your output structure)
final_result <- do.call(rbind, lapply(result_list, function(x) x$Distance))

2. Verify Single Request First (Debug Step) #

To confirm this is the issue, test a single request with non-vector inputs — if this works, you’ll know vector inputs were the problem:

# Test with the first element of each vector
test_request <- gmapsdistance(
  origin = origin_vector[1],
  destination = destination_vector[1],
  combinations = "pairwise",
  mode = "driving",
  shape = "long",
  dep_date = date_vector[1],
  dep_time = time_vector[1]
)

# Check if test_request returns valid data
str(test_request)

Quick Notes #

• Double-check your date_vector is formatted as YYYY-MM-DD and time_vector as HH:MM:SS — Google’s API requires these exact formats, and wrong formatting can also trigger XML errors.
• Keep an eye on your Google API quota! Looping through requests means you’ll make one API call per combination, so make sure you don’t exceed your allowed limits.

内容的提问来源于stack exchange，提问作者Aris123