R Ggplot2没有'；不要全部打印

我不明白为什么我的代码不起作用：

    if(formula=="ValueA"){
      df<-melt(f,id =c("ValueA"))
      colnames(df)[colnames(df) == 'variable'] <- 'Time'

      if(yaxis=="YA"){
        colnames(df)[colnames(df) == 'value'] <- 'YA'
        pl<- ggplot(df, aes(Time, YA, fill=ValueA))}
      if(yaxis=="YB"){
        colnames(df)[colnames(df) == 'value'] <- 'YB'
        pl<- ggplot(df, aes(Time, YB, fill=ValueA))} 
      if(yaxis=="YC"){
        colnames(df)[colnames(df) == 'value'] <- 'YC'
        pl<- ggplot(df, aes(Time, YC, fill=ValueA))} 
      if(yaxis=="YD"){
        colnames(df)[colnames(df) == 'value'] <- 'YD'
        pl<- ggplot(df, aes(Time, YD, fill=ValueA))}

      if(type=="line"){
        pl + geom_line(aes(color=ValueA,group=ValueA)) +theme(
          axis.text.x = element_text(angle = 90, hjust = 1))+ ggtitle(paste(title))+  YD theme( panel.border = element_rect(colour = "black", fill=NA, size=1),legend.direction ="vertical",legend.position = "right")+guides(color=guide_legend(ncol=1))+scale_y_continuous(labels=comma)  
      }
      if(type=="bar"){
        pl + geom_bar(stat="identity") +theme(
          axis.text.x = element_text(angle = 90, hjust = 1))+ ggtitle(paste(title))+  YD theme( panel.border = element_rect(colour = "black", fill=NA, size=1),legend.direction ="vertical",legend.position = "right")+guides(fill=guide_legend(ncol=1))+scale_y_continuous(labels=comma)    
      }  
    }
    if(formula=="ValueB"){
      df<-melt(f,id =c("ValueB"))
      colnames(df)[colnames(df) == 'variable'] <- 'Time'

      if(yaxis=="YA"){
        colnames(df)[colnames(df) == 'value'] <- 'YA'
        pl<- ggplot(df, aes(Time, YA, fill=ValueB))}
      if(yaxis=="YB"){
        colnames(df)[colnames(df) == 'value'] <- 'YB'
        pl<- ggplot(df, aes(Time, YB, fill=ValueB))} 
      if(yaxis=="YC"){
        colnames(df)[colnames(df) == 'value'] <- 'YC'
        pl<- ggplot(df, aes(Time, YC, fill=ValueB))} 
      if(yaxis=="YD"){
        colnames(df)[colnames(df) == 'value'] <- 'YD'
        pl<- ggplot(df, aes(Time, YD, fill=ValueB))}

      if(type=="line"){
        pl+ geom_line(aes(color=ValueB,group=ValueB))+theme(
          axis.text.x = element_text(angle = 90, hjust = 1))+ ggtitle(paste(title))+  YD theme( panel.border = element_rect(colour = "black", fill=NA, size=1),legend.direction ="vertical",legend.position = "right")+guides(color=guide_legend(ncol=1)) +scale_y_continuous(labels=comma)   
      }
      if(type=="bar"){
        pl + geom_bar(stat="identity")+theme(
          axis.text.x = element_text(angle = 90, hjust = 1))+ ggtitle(paste(title))+  YD theme( panel.border = element_rect(colour = "black", fill=NA, size=1),legend.direction ="vertical",legend.position = "right")+guides(fill=guide_legend(ncol=1)) +scale_y_continuous(labels=comma)   
      }  
    } 


  print(pl)
}
Plotsf<-Plots(Df,"Title","line","YA")

输出是完美的。有人可以解释为什么

pl+

不起作用？

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谢谢

所以答案是将变量带入，而不仅仅是写：

pl + ... added stuff

这是毫无意义的。。。改用：

pl <- pl + ... added stuff

---

pl也许可以试试
pl@Dilettant它奏效了……谢谢，对不起，但我对这些东西很在行。我从中得出了答案。如果您愿意，可以接受；-）
pl <- pl + ... added stuff