如何将条形图更改为降序排列？

我希望图表中的条形按降序排列。有没有办法自动执行此操作？我看过类似的问题但没有成功。

initialmth <- structure(list( 
  A = c( 10, 4),
  B = c(28, 18),
  C = c(9, 1), 
  D = c(39, 33),
  E = c(13, 8),
  F = c(37, 27), 
  G = c(30, 51), 
  H = c(31, 41)),  


  .Names = c("Math has been my worst subject ",
             "I would consider a career that uses math ",
             "Math is hard for me",
             "I am the type of student to do well in math",
             "I cannot do a good job with math",
             "I could do advanced work in math",
             "I can get good grades in math",
             "I am good at math"
  ), 
  class = "data.frame", 
  row.names = c(NA, -2L)) #4L=number of numbers in each letter vector#

attach(initialmth)
print(initialmth)
par(mar=c(0, 17, 1, 2.1))
colors <- c("slategray3", "dodgerblue4")
byb <- barplot(as.matrix(initialmth), 
               beside = F, ylim = range(0, 15), xlim = range(0, 100),
               horiz = T, col=colors,  main="N=96", xaxt="n", border=F, las=1, width 
               = 1.45)
# labels
labs <- data.frame(x=as.vector(sapply(M, xFun)),  # apply `xFun` here 
                   y=rep(byc, each=nrow(M)),  # use `byc` here
                   labels=as.vector(apply(M, 1:2, paste0, "%")), 
                   stringsAsFactors=FALSE)
labs$labels[labs$labels %in% paste0(0:(8*100)/100, "%")] <- "" #masks labels <8

invisible(sapply(seq(nrow(labs)), function(x)  # `invisible` prevents unneeded 
  console output
  text(x=labs[x, 1:2], labels=labs[x, 3], cex=.9, font=2, col=0)))

我希望使用基本 R 按降序重新排列条形。

您可以像这样订购数据矩阵：

par(mar=c(0, 17, 1, 2.1))
M <- as.matrix(initialmth)
o <- order(colSums(M))

colors <- c("slategray3", "dodgerblue4")
byb <- barplot(M[,o], 
               beside = F, ylim = range(0, 15), xlim = range(0, 100),
               horiz = T, col=colors,  main="N=96", xaxt="n", border=F, las=1, width 
               = 1.45)