使用lapply从数据表创建多个格子图 [英] Create multiple lattice plots from a data table using lapply

问题描述

我试图为众多变量（物种）中的每一个生成平均值，然后分别绘制每个变量。我试过列表和数据表格式。 base plot函数在for循环中工作：

  library（data.table）
 
 for i in 3：5）{
＃生成列号为i b $ b temp <-v 2 [，lapply（.SD，mean），by =Season的物种的平均值列表， .subcols = i] 
＃将列表中的每一列作为散点图绘制，主标题=第二列的标题b $ b plot（temp [[2]]〜temp [[1]]，main = colnames （temp）[[2]]）
} 
  

但是当我尝试创建格对于最后一个变量，只生成一个图：

  library（data.table）
 library（lattice） 
 
（i in 3：5）{
＃根据列号i 
 temp < -  v2 [，lapply（ .SD，mean），by = c（Season，Location），.SDcols = i] 
＃在单独的小图中的每个组
 xyplot（temp [[3]]〜temp [[1]] | temp [[2]]，main = colnames（temp）[3]）
} 
  

试过了保存或打印每个格子图，这是正确的想法？也许我一直在想这个错误的方式？

这是我的数据的一个小样本：

<$ p结构（列表（位置=结构（c（1L，1L，1L，1L，4L，4L，
4L，6L，6L，1L），。标签= c（ BN，BS，GN，GS，SB，SL，
，class = （1995），1995L，1995L，1997L，1997L，2000L），Agrostis.magellanica = c（0.3，
0.3,0.3,0.01,0.6,0.3,0.3,0.3,0.6,0.05），Festuca.contracta = c （0.6，
0.05,0.3,0.01,0.01,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0） ），.Names = c（Location，
Season，Agrostis.magellanica，Festuca.contracta，Poa.annua
），class = c（data.table，data.frame），row.names = c（NA，-10L
）

解决方案

在R-FAQ中，需要一个 print ggplot）当在一个函数中使用时，a nd for 循环是一个函数：

 ＃需要
在定义对象之前需要（data.table）＃。 
 
 pdf（）＃pdf是一个多页面设备。 
 for（i in 3：5）{
＃根据列数i 
 temp < -  v2 [，lapply（.SD，mean， ），by = c（Season，Location），.SDcols = i] 
＃在一个单独的迷你小区
 print（xyplot（temp [[3]]〜temp [ 1]] | temp [[2]]，main = colnames（temp）[3]））
} 
 dev.off（）＃无法正确关闭文件图形设备是常见错误。 
  

I am trying to generate mean values by group for each of numerous variables (species) and then plot each of these separately. I have tried list and data table formats. The base plot function works in a for loop:

library(data.table)

      for (i in 3:5) {
      # generate a list of mean value for the species in column number i
      temp <- v2[, lapply(.SD, mean), by="Season", .SDcols=i]
      # plot each col of the list as a scatterplot with main title = header of 2nd col
      plot(temp[[2]]~temp[[1]], main = colnames(temp)[[2]])
    }

But when I try to create lattice plots only a single plot is generated for the last variable:

library(data.table)
library(lattice)

for (i in 3:5) {
  # generate a list of mean value by season for the species in column number i
  temp <- v2[, lapply(.SD, mean), by=c("Season", "Location"), .SDcols=i]
  # Each group in a separate mini plot
  xyplot(temp[[3]]~temp[[1]] | temp[[2]], main = colnames(temp)[3])
}

Have tried saving or printing each lattice plot, is that the right idea? Perhaps I am going about this the wrong way altogether?

Here is a small sample of my data:

    structure(list(Location = structure(c(1L, 1L, 1L, 1L, 4L, 4L, 
4L, 6L, 6L, 1L), .Label = c("BN", "BS", "GN", "GS", "SB", "SL"
), class = "factor"), Season = c(1981L, 1981L, 1981L, 1981L, 
1995L, 1995L, 1995L, 1997L, 1997L, 2000L), Agrostis.magellanica = c(0.3, 
0.3, 0.3, 0.01, 0.6, 0.3, 0.3, 0.3, 0.6, 0.05), Festuca.contracta = c(0.6, 
0.05, 0.3, 0.01, 0.01, 0, 0, 0, 0.01, 0.05), Poa.annua = c(0.01, 
0.01, 0.01, 0.01, 0.01, 0.01, 0.01, 0.05, 0.01, 0.01)), .Names = c("Location", 
"Season", "Agrostis.magellanica", "Festuca.contracta", "Poa.annua"
), class = c("data.table", "data.frame"), row.names = c(NA, -10L
)

解决方案

This is in the R-FAQ. Need a print statement around grid graphics (lattice or ggplot) when used inside a function, and the for loop is a function:

# Needed
require(data.table)  # before defining the object.

pdf()  # pdf is a multipage device.
for (i in 3:5) {
  # generate a list of mean value by season for the species in column number i
  temp <- v2[, lapply(.SD, mean), by=c("Season", "Location"), .SDcols=i]
  # Each group in a separate mini plot
  print( xyplot(temp[[3]]~temp[[1]] | temp[[2]], main = colnames(temp)[3]) )
}
dev.off()  # Failing to properly close a file graphics device is common error.

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