Error retrieving article citation history about scholar HOT 2 CLOSED

Google can restrict users if they submit too many queries to Scholar in a short period of time; this is likely to result in scholar getting an unexpected result and returning the error you are seeing. It's hard to know exactly where the thresholds lie and it may vary with load, time of day, etc, hence why you only see it occasionally.

One possibile fix would be to add a delay into your for loop, something like:

for (i in 1:nrow(CiteYear)) {
    ...
    # Add an arbitrary 10 second delay every 20 rows
    if (i %% 20 == 0)  Sys.sleep(10) 
}

You might need to play around with the exact timing of the delay but it should help you get past any throttling restrictions. Though of course, your code will take longer to run!

from scholar.

ah, yes! Of course, I should have thought of google restrictions like that. That did the trick!

from scholar.