How to skip NA values in for loop - r

Question

I'm applying a for loop to generate multiple API requests from the RePEc database. Unfortunately, the data is not reproducible because my access code the administrator gave me only works on my IP address but I'm hoping someone can help me figure out what I've done wrong in my for loop (I'm not great at writing for loops).
Basically, I have a column of 80,000 cells df$author_reg_2with a whole lot of NA values. I want to skip the NA values and only generate API requests for cells with an actual value in them.
url <- "https://api.repec.org/call.cgi?code=USERCODE&getauthorrecordraw="
affiliation_2 <-vector(length=length(df$author_reg_2))
for(i in 1:length(df$author_reg_2))
try({
Sys.sleep(1)
if(is.na(df$author_reg_2)) next
affiliation_fun <- paste0(url,df$author_reg_2[i])
affiliation_run <- fromJSON(txt=affiliation_fun) %>% select("affiliation")
affiliation_2[i] <- paste(unlist(affiliation_run), collapse =" ")
print(i)
})
Each time I try to run this script, it still generates errors telling me that it's running the NA values.
Any help appreciated! Thank you in advance!

Answer 1

As we are looping over each element and passing the logic on if(takes a length of 1 and output 1), need the single element
url <- "https://api.repec.org/call.cgi?code=USERCODE&getauthorrecordraw="
affiliation_2 <-vector("list", length=length(df$author_reg_2))
for(i in seq_along(df$author_reg_2))
try({
Sys.sleep(1)
if(is.na(df$author_reg_2[i])) next
affiliation_fun <- paste0(url,df$author_reg_2[i])
affiliation_run <- fromJSON(txt=affiliation_fun) %>% select("affiliation")
affiliation_2[[i]] <- paste(unlist(affiliation_run), collapse =" ")
print(i)
})
The list would also hold vector of different length and there is no need to paste and collapse at the end (if that is the case)
If we need to change next to have a NA value in `affliation_2
for(i in seq_along(df$author_reg_2))
try({
Sys.sleep(1)
if(is.na(df$author_reg_2[i])) {
affiliation_2[[i]] <- NA_character_
} else{
affiliation_fun <- paste0(url,df$author_reg_2[i])
affiliation_run <- fromJSON(txt=affiliation_fun) %>% select("affiliation")
affiliation_2[[i]] <- paste(unlist(affiliation_run), collapse =" ")
}
print(i)
})