数据帧r和二进制列中使用的顶部字

I have a dataframe like this

我有这样的数据帧

df=  data.frame(
    text= c("test and run", "rest and sleep", "test", "test of course"), 
    id = c('a','b','c','d'))
#            text id
#1   test and run  a
#2 rest and sleep  b
#3           test  c
#4 test of course  d
df=