R package "scholar" / getting the citation history of an article

I have a problem with the R package scholar

What works:

get_citation_history(SSalzberg)

What doesn't:

get_article_cite_history(SSalzberg, "any article")

Code:

article <- "Ultrafast and memory-efficient alignment of short DNA sequences to the human genome"
SSalzberg <- "sUVeH-4AAAAJ" (Google Scholar ID)
get_article_cite_history(SSalzberg, article)

Error Message:

Error in min(years):max(years) : result would be too long a vector
In addition: Warning messages:
1: In min(years) : no non-missing arguments to min; returning Inf
2: In max(years) : no non-missing arguments to max; returning -Inf

I do not understand the error message in the context of that function and I tried another paper with an another author without success. I don't know what I am missing here.... Thanks

Solution

You have to use an article ID, not the title of the article. Probably the easiest way to get this is to retrieve the full list of pubs, which has a pubid column ...

library(scholar)
SSalzberg <- "sUVeH-4AAAAJ"
all_pubs <- get_publications(SSalzberg)
## next step is cosmetic -- the equivalent of stringsAsFactors=FALSE
all_pubs <- as.data.frame(lapply(all_pubs,
         function(x) if (is.factor(x)) as.character(x) else x))
w <-grep("Ultrafast",all_pubs$title) ## publication number 3
all_pubs$title[w]
## [1] Ultrafast and memory-efficient alignment of ...
all_pubs$pubid[w] ## "Tyk-4Ss8FVUC"
ch <- get_article_cite_history(SSalzberg,all_pubs$pubid[w])
plot(cites~year,ch,type="b")