Appending rows to existing Dataframe in R - r

Question

I am extracting twitter data using the twitteR package and storing them in a dataframe x.
I first created the dataframe.
x <- data.frame(
name = character(),
screen_name = character(),
id = integer(),
description = character(),
statuses_count = integer(),
followersCount = integer(),
favoritesCount = integer(),
friendsCount = integer(),
url = character(),
created = integer(),
verified = integer(),
profile_image_url = character(),
stringsAsFactors=FALSE
)
Then created a function to return the data of a specific user
adduserdata <- function(username = ""){
user <- getUser(username)
userdata = c(name = user$name,
screen_name = user$screenName,
id = user$id,
description = user$description,
statuses_count = user$statusesCount,
followersCount = user$followersCount,
favoritesCount = user$favoritesCount,
friendsCount = user$friendsCount,
url = user$url,
created = user$created,
verified = user$verified,
profile_image_url = user$profileImageUrl)
return(userdata)
}
I now want to get the data of each user in the list ns and append them to the dataframe x
ns <- c("realDonaldTrump","BarackObama")
for (n in ns) {
user <- adduserdata(n)
x <- bind(x, user)
}
But I get an error stating 'invalid factor level'. I'm not sure why.

Answer 1

Return a dataframe from addUser function.
adduserdata <- function(username = ""){
user <- getUser(username)
userdata = data.frame(name = user$name,
screen_name = user$screenName,
id = user$id,
description = user$description,
statuses_count = user$statusesCount,
followersCount = user$followersCount,
favoritesCount = user$favoritesCount,
friendsCount = user$friendsCount,
url = user$url,
created = user$created,
verified = user$verified,
profile_image_url = user$profileImageUrl)
return(userdata)
}
and try :
result <- do.call(rbind, lapply(ns, adduserdata))
Or
result <- purrr::map_df(ns, adduserdata)