R 使用可变样本大小从数据帧中随机采样

我有一个数据帧，lexicon，有650个单词，我想通过从lexicon中随机 Select 单词，为5个说话者创建一系列随机单词列表.我想在为期24个月的数据收集期间完成这项工作，每个月都会采集不同大小的词汇样本.指定月份和词汇表大小的基本数据帧为df1:

df1 <- data.frame(months=rep(1:24, times=5, each=1),
                  vocab_size=(sample(c(0:25), 120, replace=TRUE)),
                  Speaker=rep(c("A", "B", "C", "D", "E"), times=1, each=24))

list1 <- split(df1, f=df1$Speaker)

lexicon大概是这样的:

lexicon <- data.frame(c("a", "about", "above", "ain't", "all", "am", "an", "and",  
                        "animal",  "ankle", "ant" ,"any", "apple","applesauce", 
                        "asleep", "at",  "ate",  "aunt", "auntie",  "aunty's", 
                        "awake", "away", "baa", "baby" , "baby+doll", "bad" ,
                        "ball", "balloon", "banana", "basket", "bat", "bath", 
                        "bathing", "bathtub", "be", "beach", "bead", "bean",
                        "because", "bed", "beddy", "bee", "been", "behind",
                        "being", "belt", "bench", "bib", "bicycle", "big"))

在使用以下代码之后，我一直在try 生成我想要的输出:

vocab_data <- lapply(list1, FUN=function(element) {
  all_vocab <- slice_sample(lexicon, n=element$vocab_size, replace=TRUE)
})

但我收到以下错误消息

 Error in `slice_sample()`:
 ! `n` must be a constant.
 Caused by error in `element$vocab_size`:
 ! $ operator is invalid for atomic vectors

有没有办法通过这种方式从数据框中提取不同大小的样本， for each 说话者创建一个每个月的词汇表？