根据时间为findAssocs结果创建热图

Question

我有以下数据，首先为它们创建一个文档术语矩阵，然后将时间变量添加到dtm中。为了了解不同年份中与“ updat”一词的相关性，我想以x轴显示时间的方式为findAssoc提供一个热图。

library(tm) 
library(ggplot2)

df <- structure(list(Description = structure(c(5L, 8L, 6L, 4L, 1L,
2L, 7L, 9L, 10L, 3L), .Label = c("general topics done", "keep the general topics updated",
 "rejected topic ", "several topics in hand", "this is a genetal topic",
 "topic 333555 needs to be updated", "topic 5647 is handed over",
 "topic is updated", "update the topic ", "updating the topic is done "
  ), class = "factor")), class = "data.frame", row.names = c(NA,
  -10L))
corpus=Corpus(VectorSource(df$Description))
corpus=tm_map(corpus,tolower)
corpus=tm_map(corpus,removePunctuation)
corpus=tm_map(corpus,removeWords,c(stopwords("english")))
corpus=tm_map(corpus,stemDocument,"english")

frequenciescontrol=DocumentTermMatrix(corpus)
frequenciescontrol$time=c("2015","2015","2015","2015","2015","2016","2016","2016","2016","2016")
findAssocs(frequenciescontrol, "updat", 0.01)

所以我想要一个热图，其中y轴显示与“ updat”相关的单词，x轴显示年份。