使用mapply使用列名作爲參數

Question

感興趣的數據生成圖表是mymeanDT

DT <- data.table(yearmonth = as.yearmon(sample(seq(as.Date('2012/07/01'), as.Date('2016/02/28'),by="day"), 5000, replace = TRUE)), 
      mydummy = as.factor(rbinom(5000, 1, .4)), X = runif(5000, 0, 1), Y = rnorm(5000, 20, 5), Z = runif(5000, 4, 6)) 

mymeanDT <- DT[, lapply(.SD, function(x) mean(x, na.rm = TRUE)), by = .(mydummy, yearmonth), .SDcols = c("X", "Y", "Z")] 

我需要繪製行所有列，通過yearmonth和mydummy。我能做到這與以下

mycolnames <- c("X", "Y", "Z") 
my_lapply_plots <- lapply(mymeanDT[, mycolnames, with = FALSE],function(mycol) 
    ggplot(mymeanDT, aes(x = yearmonth,y = mycol)) + 
    geom_line(aes(linetype = mydummy, color = mydummy)) + scale_x_yearmon() + xlab("") + ylab("") + 
    theme(plot.title = element_text(size = 14, hjust = -0.03)) + 
    scale_linetype_manual(values=c("longdash", "solid"), breaks=c(0,1),labels=c("N", "Y")) + 
    scale_color_manual(values=c("#701B45", "#007FAE"), breaks=c(0,1),labels=c("N", "Y")) + 
    ggtitle(paste("Some", "title", sep = " ")) 
) 

我想在標題中使用的列名。所以，我想通過一個類似的功能，通過mapply

my_mapply_plots <- mapply(function(mycol, mynames) 
    ggplot(mymeanDT, aes(x = yearmonth,y = mycol)) + 
    geom_line(aes(linetype = mydummy, color = mydummy)) + scale_x_yearmon() 
    + xlab("") + ylab("") + 
    theme(plot.title = element_text(size = 14, hjust = -0.03)) + 
    scale_linetype_manual(values=c("longdash", "solid"), breaks=c(0, 1), 
     labels=c("N", "Y")) + 
    scale_color_manual(values=c("#701B45", "#007FAE"), breaks=c(0, 1), 
     labels=c("N", "Y")) + 
    ggtitle(paste("Some", mycolnames, sep = " ")), 
    mycol = mymeanDT[, mycolnames, with = FALSE], mynames = mycolnames) 

但這是輸出我得到

my_mapply_plots 

  X  Y  Z  
data  List,5 List,5 List,5 
layers  List,1 List,1 List,1 
scales  ?  ?  ?  
mapping  List,2 List,2 List,2 
theme  List,1 List,1 List,1 
coordinates ?  ?  ?  
facet  ?  ?  ?  
plot_env ?  ?  ?  
labels  List,6 List,6 List,6 

任何幫助，將不勝感激

Answer 1

我想你應循環mycolnames - 向量lapply來獲得想要的地塊。使用：

lapply(mycolnames, function(column) { 
    ggplot(data = mymeanDT, 
     aes(x = yearmonth, y = mymeanDT[[ column ]], linetype = mydummy, color = mydummy)) + 
    geom_line() + scale_x_yearmon() + 
    ggtitle(paste("Some", column, sep = " ")) 
}) 

會給你3個地塊。

第一招：

如果你想存儲：

myplots <- lapply(mycolnames, function(column) { 
    ggplot(data = mymeanDT, 
     aes(x = yearmonth, y = mymeanDT[[ column ]], linetype = mydummy, color = mydummy)) + 
    geom_line() + scale_x_yearmon() + 
    ggtitle(paste("Some", column, sep = " ")) 
}) 

打字然後myplots將打印的三個地塊。然後，您也可以使用myplots[[1]]（或：myplots[1]）