R多绘图可视化

Question

我正在使用此代码绘制多重绘图：

multiplot <- function(plotlist=NULL, cols) {
  require(grid)

  # Make a list from the ... arguments and plotlist
  plots <- c(plotlist)

  numPlots = length(plots)

  # Make the panel
  plotCols = cols                       # Number of columns of plots
  plotRows = ceiling(numPlots/plotCols) # Number of rows needed, calculated from # of cols

  # Set up the page
  grid.newpage()
  pushViewport(viewport(layout = grid.layout(plotRows, plotCols)))
  vplayout <- function(x, y)
    viewport(layout.pos.row = x, layout.pos.col = y)

  # Make each plot, in the correct location
  for (i in 1:numPlots) {
    curRow = ceiling(i/plotCols)
    curCol = (i-1) %% plotCols + 1
    print(plots[[i]], vp = vplayout(curRow, curCol ))
    title(paste(product_name,'_ROC___AUC = ', mroc$auc))
  }

}

致电

multiplot(list(ggplot1,ggplot2,ggplot3,ggplot4,ggplot5,ggplot6,linear_pred,roc_plot), cols=3)

我将成功呈现所有绘图（请参阅附件），除了最后创建的绘图：

rc <- roc(mnm.predict.test.class[[1]],mnm.predict.test.probs.max[[1]])

roc_plot <- plot(rc) 

看起来像这样： 它是基于多项分类模型的ROC图，该模型由以下人员创建：

mnm <- multinom(formula = cut.rank ~ ., data = training.logist, trace = FALSE, maxit = 1000)
    # predict on test set
    mnm.predict.test.class <- as.data.frame(predict(mnm, newdata =testing.logist, type="class"))
    mnm.predict.test.probs <- as.data.frame(predict(mnm, newdata =testing.logist, type="probs"))
    mnm.predict.test.probs.max <- as.data.frame(apply(mnm.predict.test.probs, 1, max))

我的多重作用函数是否拒绝绘制ROC？