ddply and ggplot - generating no plot [duplicate]

问题

I have a data which is given below:

> dput(qq)
structure(list(SIC = c(50, 50, 50, 50, 50, 50, 50, 50, 50, 50, 
50, 50, 50, 50, 50, 50, 50, 50, 50, 50), AVGAT = c(380.251, 391.3885, 
421.72, 431.83, 483.715, 600.0715, 698.5945, 733.814, 721.426, 
706.0265, 698.41, 697.9565, 720.761, 855.5245, 1023.226, 1214.8215, 
1369.7605, 1439.2765, 1602.3845, 1949.69), ADA = c(0.0223312309851002, 
0.00984600086327487, 0.0199212814576842, 0.0562291585405388, 
0.0155376903911516, 0.0195296616004618, 0.00650206622557842, 
0.0295510054117198, 0.0471091745681615, 0.0898164879903691, 0.154998113255882, 
0.0347106350470676, 0.109407241662021, 0.057428893735577, 0.0637457846236655, 
0.0584883505633773, 0.0439293152619417, 0.030699982198924, 0.00900414418496609, 
0.0293862740698763), NLEAD = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 0)), .Names = c("SIC", "AVGAT", "ADA", 
"NLEAD"), row.names = c(NA, 20L), class = "data.frame")

When I run the following code, the code doesn't plot anything:

clusmypath <- file.path("C:", "Users", "Swordfish", "Dropbox", "aaa.pdf");
pdf(file = clusmypath);
library(ggplot2);
ww <- ddply(qq, .(SIC), function(p){ggplot(p,aes(x=AVGAT,y= ADA, color = NLEAD)) + geom_point(shape=1) ;return(p)});
dev.off();

However, when I plot the full data :

clusmypath <- file.path("C:", "Users", "Swordfish", "Dropbox", "aaa.pdf");
pdf(file = clusmypath);
library(ggplot2);
ggplot(qq, aes(x = AVGAT, y = ADA, color = NLEAD)) + geom_point(shape=1)  
dev.off();

I get a plot. How can I make ddply part to work? Thanks.

回答1:

return(p) in your script doesn't return a plot. p refers to each subset of the data frame qq. In general, to 'return' plots produced by ggplot inside functions you need to use print (see FAQ 7.22). However, in your particular case, where you want to save plots, you don't need print.

Several PDF files

If you want one file per level of 'SIC', you may try something like this. d_ply is useful when you call a function only for its side effects, like here when we save the output from a plot. Instead of pdf/some-plotting/dev.off, you may use ggsave.

d_ply(qq, .(SIC), function(p){
  ggplot(p, aes(x = AVGAT, y = ADA, color = NLEAD)) + geom_point(shape = 1)
  ggsave(file = paste0(unique(p$SIC), ".pdf"))
  })

One PDF file with several pages

If you want one PDF file, with one page per level of 'SIC', you may use base function pdf, and the .print = TRUE argument in d_ply.

# create a new SIC variable with two levels, for a more realistic test of the function
qq$SIC2 <- rep(c(50, 100), each = 10)

pdf(file = "aaa.pdf")

d_ply(qq, .(SIC2), .print = TRUE, function(p){
ggplot(p, aes(x = AVGAT, y = ADA, color = NLEAD)) + geom_point(shape = 1)
})

dev.off()

来源：https://stackoverflow.com/questions/20048287/ddply-and-ggplot-generating-no-plot

标签

ggplot2

plyr