I am trying to apply the function ggplotGrob() to a list of ggplots using lapply but can't seem to be able to obtain a list of grob objects out of it. For this project, a variable number of plots are generated based on user input, and I need a dynamic way to generate the grid. I need to define grobs from the plots to assign the same width to all charts before display.
For example, I have plots p1 and p2. If I do it manually:
gp1 <- ggplotGrob(p1)
gp2 <- ggplotGrob(p2)
grid.arrange(gp1, gp2, ncol=1)
I get my 2 plots.
Now if I do
gp_list <- list(gp1,gp2)
grid.arrange(gp_list, ncol=1)
I get an error message
Error in arrangeGrob(..., as.table = as.table, clip = clip, main = main, : input must be grobs!
I tried to use unlist() but I got the same error
grid.arrange(unlist(gp_list), ncol=1)
Eventually, I would like to build the list of grobs through lapply as such
gp_list <- lapply(plot_list, function(x) ggplotGrob(x))
and be able to arrange all the grobs using grid.arrange. I feel like I m forgetting a simple step to retrieve each object from the list as a grob. Anybody solved this?
Thanks
> sessionInfo()
R version 3.1.1 (2014-07-10)
Platform: x86_64-apple-darwin13.1.0 (64-bit)
locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] grid parallel stats graphics grDevices utils datasets methods base
other attached packages:
[1] pryr_0.1 WGCNA_1.41-1 flashClust_1.01-2 dynamicTreeCut_1.62 gridExtra_0.9.1 ggplot2_1.0.0
[7] gplots_2.14.1 hash_2.2.6 shiny_0.10.1 Biobase_2.24.0 BiocGenerics_0.10.0
