如何在热图中用R来显示所有年份？“Y”标签中的一些年份丢失了。是否可以用一个Angular 或交替位移来显示所有年份？

year = seq(from=1971,to=2020,by=1)
jan = runif(n = 50, min = -3, max = 3)
feb = runif(n = 50, min = -3, max = 3)
mar = runif(n = 50, min = -3, max = 3)
apr = runif(n = 50, min = -3, max = 3)
may = runif(n = 50, min = -3, max = 3)
jun= runif(n = 50, min = -3, max = 3)
jul= runif(n = 50, min = -3, max = 3)
aug= runif(n = 50, min = -3, max = 3)
sep= runif(n = 50, min = -3, max = 3)
oct= runif(n = 50, min = -3, max = 3)
nov= runif(n = 50, min = -3, max = 3)
dec= runif(n = 50, min = -3, max = 3)

df = data.frame(year,jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec)
head(df)
rownames(df) <- df$year
df=df[,-1]
df=as.matrix(df)
head(df)
my_palette <- colorRampPalette(c("red", "white", "blue"))(n = 9)

heatmap.2(df, scale = "none", col = my_palette, 
          trace = "none", density.info = "none", main = "Bohicon")

谢谢你