getting only the unique tweets from tweets extracted with python

setwd("N:\\Tweeter\\output")
tweets<-read.csv("output_Roman_Empire_Trump_.csv")

uniqueTweets <- as.data.frame(table(tweets[[2]]))
uniqueTweets <- uniqueTweets[with(uniqueTweets, order(-Freq)), ]
length(uniqueTweets[[2]])
write.csv(uniqueTweets[[1]],"Roman_Empire_Trump.csv")
save(uniqueTweets,file="Roman_Empire_Trump.R")