使用lodown包下载AHS微观数据失败，出现多行警告

Hey there, let's walk through troubleshooting this issue you're hitting with the lodown package's get_catalog() function for AHS data. Those repeated "incomplete final line" warnings and the failed catalog fetch are likely tied to temporary file quirks, download method limitations, or minor hiccups in how Census HTML pages are being parsed.

Here are actionable steps to resolve this:

1. Clear R's Temporary Files #

The warnings point to a temp file that didn't read correctly—this often happens when old temporary files pile up and cause conflicts. Clear the temp directory and restart R to start fresh:

# Clear all temporary files
unlink(tempdir(), recursive = TRUE)
# Restart your R session now, then re-run the catalog fetch

2. Switch the Download Method #

Windows default download methods can sometimes struggle with Census HTML pages. Try forcing a more reliable download method:

# For Windows users, use wininet
options(download.file.method = "wininet")

# For macOS/Linux users (or if wininet doesn't work), use libcurl
# options(download.file.method = "libcurl")

# Ensure your target directory exists first
ahs_dir <- file.path(path.expand("~"), "AHS")
dir.create(ahs_dir, recursive = TRUE, showWarnings = FALSE)

# Now run the catalog fetch again
ahs_cat <- get_catalog("ahs", ahs_dir)

3. Verify URL Access and Page Structure #

The error mentions a 1973 AHS page—open this URL directly in your browser to confirm it loads properly:
https://www.census.gov/programs-surveys/ahs/data/1973/ahs-national-puf-microdata.html
(Note: The double slash in the URL R tried is harmless, but confirming the page loads rules out a broken Census link.)

If the page loads but has unusual formatting (like missing closing HTML tags), lodown's parsing might get tripped up. This is rare, but if it happens, you could manually download the HTML file to your AHS directory and see if lodown can read it locally (a last-resort fix).

4. Check Directory Permissions #

Make sure your user account has full read/write access to the ~AHS directory. Test this by writing a dummy file there:

test_file <- file.path(ahs_dir, "test.txt")
writeLines("test", test_file)
file.exists(test_file) # Should return TRUE
file.remove(test_file)

If this fails, adjust the directory permissions or choose a simpler path (like C:/AHS instead of the user home folder).

内容的提问来源于stack exchange，提问作者user9620331