多重控制图 EWMA RStudio

Question

I am trying plot multiples control chart type EWMA in just a plot in software RStudio, using the function par, but, there aren't output error and the each controlchart is plotted in the same local graph, not in the different position.

par(mfrow=c(2,2),new=TRUE) q2 <- ewma(x2,center = 0, lambda=0.4,std.dev=0.57, nsigmas=3,add.stats='False') par(new=TRUE) q3 <- ewma(x3,center = 0, lambda=0.4,std.dev=0.57, nsigmas=3,add.stats='False') #par(new=TRUE) q4 <- ewma(x4,center = 0, lambda=0.4,std.dev=0.57, nsigmas=3,add.stats='False') #par(new=TRUE) q5 <- ewma(x5,center = 0, lambda=0.4,std.dev=0.57, nsigmas=3,add.stats='False')

I would like to plot four control chart in this plot, but, actually, each control chart is insert in the same position:

Answer 1

On further inspection, the problem is caused by the plot.ewma.qcc function from the qcc package not returning a grob. So we need to convert these objects to grobs first. cowplot gives us a way to do this:

library(qcc)
library(gridExtra)
library(cowplot)

data(pistonrings)
attach(pistonrings)
diameter <- qcc.groups(diameter, sample)

q2 <-
  ~ ewma(
    diameter[1:25, ],
    center = 0,
    lambda = 0.4,
    std.dev = 0.57,
    nsigmas = 3,
    add.stats = FALSE
  ) 

q3 <-
  ~ ewma(
    diameter[15:40, ],
    center = 0,
    lambda = 0.4,
    std.dev = 0.57,
    nsigmas = 3,
    add.stats = 'False'
  ) 

plot_list <- list(p1 = as_grob(q2), p2 = as_grob(q3))
do.call("grid.arrange", c(plot_list, ncol = 2))

Note the tilde ~ formula operator in front of the calls to the ewma function calls. This is how cowplot wants it. We then call the cowplot::as_grob function when we compile the plots into a list. do.call and grid.arrange do the rest. Which generates this plot:

Note: I am not very familiar with cowplot so it escaped me that this package has a method for grid plotting:

plot_grid(q2, q3, labels = c('A', 'B'), label_size = 12)

Which would give you the same results as above.