问题
Is it possible to control the number of panels per row in a ggplot? I can only get an equal number of panels on each row as in the example plot below.
For example I have data that is naturally grouped into 22 blocks by 'Marker' which in turn are organised by 'Dye' (see example code and data below). In this example I would like to arrange the panels in 4 rows with 5, 6, 6, and 5 panels respectively on each row (as in the picture at the end, but the 22 blocks can be equally wide).
Example code:
df$Type <- factor(round(df$Type, 2))
df$Allele <- factor(df$Allele)
gp <- ggplot(df, aes_string(x = "Allele", y = "Ratio", colour = "Type"))
gp <- gp + geom_point(alpha = 0.8, position = position_jitter(width = 0.1))
gp <- gp + facet_grid(Dye ~ Marker) + facet_wrap(~Marker, ncol = 5, drop = FALSE, scales = "free_x")
gp <- gp + guides(fill = guide_legend(reverse = TRUE))
gp <- gp + labs(title = "Stutter ratios")
print(gp)
Example data:
Marker Allele Ratio Type Dye
DYS576 18 0.116157205 -1 B
DYS389 I 14 0.043252595 -1 B
DYS448 19 0.018236074 -1 B
DYS389 II 31 0.102169982 -1 B
DYS19 14 0.058139535 -1 B
DYS19 14 0.078224101 -0.2 B
DYS391 10 0.090035245 -1 G
DYS481 22 0.013492063 -2 G
DYS481 22 0.179365079 -1 G
DYS549 13 0.0625 -1 G
DYS533 12 0.07564495 -1 G
DYS437 14 0.04757085 -1 G
DYS570 17 0.071079867 -1 Y
DYS570 17 0.007420426 1 Y
DYS635 21 0.192561983 -1 Y
DYS390 24 0.073079325 -1 Y
DYS439 12 0.084817642 -1 Y
DYS392 13 0.125965997 -1 Y
DYS393 13 0.009672831 -2 R
DYS393 13 0.079374111 -1 R
DYS393 13 0.013371266 1 R
DYS458 17 0.126099707 -1 R
DYS385 13 0.059782609 -1 R
DYS385 16 0.092356688 -1 R
DYS456 17 0.12 -1 R
YGATAH4 11 0.07203718 -1 R
DYS576 18 0.094989562 -1 B
DYS389 I 14 0.044955045 -1 B
DYS448 19 0.017171717 -1 B
DYS389 II 31 0.124137931 -1 B
DYS391 10 0.052903833 -1 G
DYS481 22 0.198726115 -1 G
DYS549 13 0.08853967 -1 G
DYS533 12 0.106617647 -1 G
DYS438 9 0.017562533 -1 G
DYS570 17 0.006710002 -2 Y
DYS570 17 0.076326274 -1 Y
DYS570 17 0.007339065 1 Y
DYS635 21 0.132272501 -1 Y
DYS390 24 0.078853047 -1 Y
DYS439 12 0.06980198 -1 Y
DYS392 13 0.104508197 -1 Y
DYS393 13 0.083853995 -1 R
DYS393 13 0.014140085 1 R
DYS458 17 0.094651285 -1 R
DYS385 13 0.076977401 -1 R
DYS385 13 0.076977401 -1 R
DYS385 16 0.059866962 -1 R
DYS385 16 0.059866962 -1 R
DYS456 17 0.151162791 -1 R
YGATAH4 11 0.09254902 -1 R
DYS576 18 0.126856684 -1 B
DYS389 I 14 0.052631579 -1 B
DYS389 II 31 0.102253033 -1 B
DYS19 14 0.056882821 -1 B
DYS19 14 0.080773606 -0.2 B
DYS391 10 0.053362122 -1 G
DYS481 22 0.033595801 -2 G
DYS481 22 0.164829396 -1 G
DYS549 13 0.123548922 -1 G
DYS533 12 0.06750174 -1 G
DYS437 14 0.041118421 -1 G
DYS570 17 0.097141001 -1 Y
DYS570 17 0.010071475 1 Y
DYS635 21 0.070416095 -1 Y
DYS390 24 0.075715605 -1 Y
DYS439 12 0.077648766 -1 Y
DYS392 13 0.116974494 -1 Y
DYS643 10 0.017945781 -1 Y
DYS393 13 0.011755878 -2 R
DYS393 13 0.121810905 -1 R
DYS393 13 0.017008504 1 R
DYS458 17 0.097028366 -1 R
DYS385 13 0.083820663 -1 R
DYS385 16 0.124661247 -1 R
DYS456 17 0.11167002 -1 R
DYS576 18 0.102416918 -1 B
DYS448 19 0.021699819 -1 B
DYS19 14 0.064239829 -0.2 B
DYS391 10 0.054468085 -1 G
DYS481 22 0.048726467 -2 G
DYS481 22 0.182724252 -1 G
DYS549 13 0.091326105 -1 G
DYS533 12 0.074295474 -1 G
DYS438 9 0.059535822 -1 G
DYS437 14 0.044034091 -1 G
DYS570 17 0.02547279 -2 Y
DYS570 17 0.129293709 -1 Y
DYS570 17 0.012350444 1 Y
DYS635 21 0.09912927 -1 Y
DYS390 24 0.086936937 -1 Y
DYS439 12 0.060550459 -1 Y
DYS392 13 0.149750416 -1 Y
DYS393 13 0.08388521 -1 R
DYS393 13 0.016188374 1 R
DYS458 17 0.009228937 -2 R
DYS458 17 0.092289372 -1 R
DYS458 17 0.062816314 1 R
DYS385 13 0.068504595 -1 R
DYS385 16 0.077120823 -1 R
DYS456 17 0.131855309 -1 R
YGATAH4 11 0.070570571 -1 R
DYS576 18 0.108604407 -1 B
DYS389 I 14 0.053097345 -1 B
DYS389 II 31 0.122986823 -1 B
DYS19 14 0.044878049 -1 B
DYS19 14 0.069268293 -0.2 B
DYS391 10 0.057256368 -1 G
DYS481 22 0.029480217 -2 G
DYS481 22 0.171450737 -1 G
DYS549 13 0.078275862 -1 G
DYS533 12 0.062146893 -1 G
DYS437 14 0.037869063 -1 G
DYS570 17 0.0956807 -1 Y
DYS570 17 0.021323127 1 Y
DYS635 21 0.076858108 -1 Y
DYS390 24 0.099143207 -1 Y
DYS439 12 0.057610242 -1 Y
DYS439 12 0.028449502 1 Y
DYS392 13 0.101621622 -1 Y
DYS393 13 0.012474012 -2 R
DYS393 13 0.117463617 -1 R
DYS393 13 0.01039501 1 R
DYS458 17 0.081623347 -1 R
DYS385 13 0.068003487 -1 R
DYS385 16 0.066376496 -1 R
DYS456 17 0.149382716 -1 R
Update: Finally had some time to try to solve this issue. Based on DWin's answer and with the help of some examples found online I have manage to create a plot almost as I wish. However I need some more help to get it exactly as I want:
1) How can I make the panels equally wide (or tall) in each plot and still be able to put in titles and legends only in some plots.
2) How can I center the y title and the legend vertically across all plots.
3) Of course I want to use the same colour for the same types in the different panels, but I suppose that should be easy using ggplot. But any advice here is also welcome.
See attached code and image for my progress so far.
# Prepare data.
df$Marker <- factor(df$Marker, levels = c("DYS576", "DYS389 I", "DYS448", "DYS389 II", "DYS19",
"DYS391", "DYS481", "DYS549", "DYS533", "DYS438", "DYS437",
"DYS570", "DYS635", "DYS390", "DYS439", "DYS392",
"DYS643", "DYS393", "DYS458", "DYS385", "DYS456", "YGATAH4" ))
df$Type <- factor(round(df$Type, 2))
df$Dye <- factor(df$Dye, levels = c("B", "G", "Y", "R"))
df$Allele <- factor(df$Allele)
# Get y max to use same scale.
yMax <- max(df$Ratio)
# Get dyes.
dyes <- levels(df$Dye)
# start new page
plot.new()
# setup layout
gl <- grid.layout(nrow=length(dyes) , ncol=1)
# grid.show.layout(gl) # To inspect layout.
# Init layout
pushViewport(viewport(layout=gl))
# Loop over all dyes.
for(d in seq(along=dyes)){
# Move to the next viewport
pushViewport(viewport(layout.pos.col=1, layout.pos.row=d))
# Create a plot for the current subset.
gp <- ggplot(subset(df, Dye==dyes[d]), aes_string(x = "Allele", y = "Ratio"))
gp <- gp + geom_point(aes_string(colour = "Type"), alpha = 0.8, position = position_jitter(width = 0.1))
gp <- gp + facet_grid(Dye ~ Marker, scales="free_x")
gp <- gp + ylim(0, yMax)
# If first dye channel.
if(d == 1){
# Plot title only.
gp <- gp + labs(title = "Stutter ratios")
gp <- gp + theme(axis.title.x=element_blank())
gp <- gp + theme(axis.title.y=element_blank())
# Remove legends.
gp <- gp + theme(legend.position="none")
} else if(d == length(dyes)){ # If last dye channel.
# No title but x and y labels.
# Y label should ideally be centered vertically in final plot.
gp <- gp + labs(title = element_blank())
gp <- gp + labs(xlab = "Allele")
gp <- gp + labs(xlab = "Ratio")
# Not removing legend works but makes the last plot more compact (horizontally).
# Can the panel height or width be fixed for all subplots?
# 'bottom' is nicer (assuming I can't center it vertically in the final plot)
# but makes the last dye channel very compact (vertically).
# gp <- gp + theme(legend.position="bottom")
} else { # No titles, labels or legends.
gp <- gp + labs(title = element_blank())
gp <- gp + theme(axis.title.x = element_blank())
gp <- gp + theme(axis.title.y = element_blank())
gp <- gp + theme(legend.position="none")
}
# Print the ggplot graphics here
print(gp, newpage = FALSE)
# Done with this viewport
popViewport(1)
}
Update 2: New try using gtable as suggesteb by baptiste. I can now produce the exact plot that I want. The only improvement in appearance I can think of is to reduce the horizontal space that the legend takes up. Happy for any suggestions on that. But I will not use more time to try and find out myself, the plot is close enough to perfect for me.
New code and plot below. The code can probably be cleaned a bit, so leave a comment if you have any tip.
# Prepare data.
df$Marker <- factor(df$Marker, levels = c("DYS576", "DYS389 I", "DYS448", "DYS389 II", "DYS19",
"DYS391", "DYS481", "DYS549", "DYS533", "DYS438", "DYS437",
"DYS570", "DYS635", "DYS390", "DYS439", "DYS392",
"DYS643", "DYS393", "DYS458", "DYS385", "DYS456", "YGATAH4" ))
df$Type <- factor(round(df$Type, 2))
df$Dye <- factor(df$Dye, levels = c("B", "G", "Y", "R"))
df$Allele <- factor(df$Allele)
# Get y max to use same scale.
yMax <- max(df$Ratio)
# Get dyes.
dyes <- levels(df$Dye)
# Number of dyes.
noDyes <- length(dyes)
# Number of rows in table object.
noRows <- length(dyes) + 2
# Create table object.
g <- gtable(widths=unit(c(1,4,1),c("lines","null","null")),
heights = unit(c(1,rep(1,noDyes),1), c("line",rep("null",noDyes), "line")))
# Add titles.
g <- gtable_add_grob(g, textGrob("Stutter ratios"), t=1,b=1,l=2,r=2)
g <- gtable_add_grob(g, textGrob("Allele"), t=noRows ,b=noRows ,l=2,r=2)
g <- gtable_add_grob(g, textGrob("Ratio", rot=90), t=1,b=noRows ,l=1,r=1)
# Create a plot for the entire dataset to extract the legend.
gp <- ggplot(df, aes_string(x = "Allele", y = "Ratio"))
gp <- gp + geom_point(aes_string(colour = "Type"))
# Extract the legend.
guide <- gtable_filter(ggplotGrob(gp), pattern="guide")
# Add the legend to the table object.
g <- gtable_add_grob(g,guide , t=1,b=noRows,l=3,r=3)
# Loop over all dyes.
for(d in seq(along=dyes)){
# Create a plot for the current subset.
gp <- ggplot(subset(df, Dye==dyes[d]), aes_string(x = "Allele", y = "Ratio"))
gp <- gp + geom_point(aes_string(colour = "Type"), alpha = 0.8, position = position_jitter(width = 0.1))
gp <- gp + scale_colour_discrete(drop = FALSE)
gp <- gp + facet_grid(Dye ~ Marker, scales="free_x")
gp <- gp + ylim(0, yMax)
# Remove titles, axis labels and legend.
gp <- gp + labs(title = element_blank())
gp <- gp + theme(axis.title.x = element_blank())
gp <- gp + theme(axis.title.y = element_blank())
gp <- gp + theme(legend.position="none")
# Add plot panel to table object.
g <- gtable_add_grob(g,ggplotGrob(gp), t=(d+1),b=(d+1),l=2,r=2)
}
# Plot.
grid.newpage()
grid.draw(g)
回答1:
An easy way to place grobs is to use the gtable package,
library(gtable)
gtable_add_grobs <- gtable_add_grob #misleading name
g <- gtable(widths=unit(c(1,4,1),c("lines","null","null")),
heights = unit(c(1,1,1,1), c("line","null","null", "line")))
lg <- list(textGrob("title"),
textGrob("xlab"),
textGrob("ylab", rot=90),
rectGrob(),
rectGrob(),
rectGrob())
pos <- data.frame(t=c(1, 4, 1, 2, 3, 2),
b=c(1, 4, 4, 2, 3, 3),
l=c(2, 2, 1, 2, 2, 3),
r=c(3, 2, 1, 2, 2, 3))
g <- with(pos, gtable_add_grobs(g, lg, t=t, l=l, b=b, r=r))
grid.newpage()
grid.draw(g)
You can extract the legend of a ggplot with gtable_filter(ggplotGrob(p), pattern="guide").
回答2:
I suspect you will need to use viewports. This will allow you to specify the layouts separately for each row.
library(grid)
?grid.layout
来源：https://stackoverflow.com/questions/17314058/ggplot2-control-number-of-panels-per-row-when-using-facet