Plot only values greater than given value: ggplot R

Question

With help from @Nick Criswell I have learned how to create a make plot function and lapply using ggplot2 and aes_string. loop Freq plot with GGPLOT aes_string

I am having trouble modifying the code to only plot values greater than a given threshold. Before using the function approach I coded the following that worked:

p <- ggplot(subset(DAT, al.sum>10), aes(word, al.sum, y=freq))

Question: how do I modify the following code to only plot values over a given threshold? i.e. I only want each record to be included in the frequency plot if the count is greater than 10. From the code below with this condition for al.sum only Dot_Matricks would be included in the plot.

#set work DIR
setwd("C:/A")

#Data create 
DAT <- read.table(text = "ID  a1.sum  b3.sum  c6.sum  d9.sum
April_Showers   10  5   15  0
              Anita_Job   2   3   1   14
              Candy_Cain  4   7   14  17
              Crystal_Ball    6   8   16  12
              Dot_Matricks    15  9   0    1
              Kay_Largo   4   10  5   13", 
              header = TRUE, stringsAsFactors = FALSE)

 #Plot Data function  
 library(ggplot2)

 make_plots = function(data, column){
 ggplot(data, aes_string(x = "ID", y=column)) +
 geom_bar(stat="identity", fill="blue", color="green") +
 theme(plot.background = element_rect(fill = "white"),
      panel.background = element_rect(fill = "white"),        
      panel.grid.major = element_line(colour = "white",size=0.25),
      panel.grid.minor = element_blank(),
      axis.text.x=element_text(size=10,angle=90, hjust=1, 
                               face="plain", family="serif"),
      axis.text.y=element_text(size=10, hjust=1, face="plain", family="serif"), 
      axis.line.x = element_line(color="black", size = 0.50), 
      axis.line.y = element_line(color="black", size = 0.5))
}

#lapply function 
myplots <- lapply(colnames(DAT[2:ncol(DAT)]), make_plots, data = DAT)

#collect names of each col that end with .sum
n <- names(DAT[grep("*.sum",names(DAT))])

#save each plot as .png
for (i in 1:length(n)){
  print(myplots[i])
ggsave(filename=paste0(i,".png"))
}

Instead of sending `data` to `ggplot()`, send `subset(data, a1.sum > 10)` — jdobres, Dec 22 '16 at 16:17
Yes, you should subset, but `subset` is thought just for interactive use, it would be better to use `data[data$a1.sum > 10, ]` — llrs, Dec 22 '16 at 16:48

score 2 · Accepted Answer · answered Dec 22 '16 at 17:00

This should do the trick:

make_plots = function(data, column,Threshold){

  PltData <- data[data[,column] >Threshold,]

  Plt <- ggplot(PltData, aes_string(x = "ID", y=column)) +
    geom_bar(stat="identity", fill="blue", color="green") +
    theme_bw()+
    theme(
      panel.grid.major = element_line(colour = "white",size=0.25),
      panel.grid.minor = element_blank(),
      axis.text.x=element_text(size=10,angle=-30, hjust=0)
    )
  # Plt
  ggsave(Plt,filename=paste0(column,".png"))
}

lapply(colnames(DAT[2:ncol(DAT)]), make_plots, data = DAT,Threshold=10)

You could do this with the subset function as well. If you want to return the plots to your R session comment the ggsave line and uncomment Plt.

Plot only values greater than given value: ggplot R

1 Answers1