I would like to make heatmaps using the following data:

dt <- data.frame(
  h = rep(LETTERS[1:7], 7), 
  j = c(rep("A", 7), rep("B", 7), rep("C", 7), rep("D", 7), rep("E", 7), rep("F", 7), rep("G", 7)),
  Red = runif(7, 0, 1), 
  Yellow = runif(7, 0, 1), 
  Green = runif(7, 0, 1),
  Blue = runif(7, 0, 1),
  Black = runif(7, 0, 1)
)

For each of the heatmaps, the x and y axes stay as the first 2 columns of df. The values that fill in each heatmap will be each of the remaining columns, e.g., Red, Yellow, ...

I borrowed this example to produce the following code:

loop = function(df, x_var, y_var, f_var) {
  
  ggplot(df, aes(x = .data[[x_var]], y = .data[[y_var]], fill = .data[[f_var]]))   
    geom_tile(color = "black")  
    scale_fill_gradient(low = "white", high = "blue")  
    geom_text(aes(label = .data[[f_var]]), color = "black", size = 4)  
    coord_fixed()  
    theme_minimal()  
    labs(x = "",
         y = "",
         fill = "R", # Want the legend title to be each of the column names that are looped
         title = .data[[f_var]])
  
  ggsave(a, file = paste0("heatmap_", f_var,".png"), device = png, width = 15, height = 15, units = "cm")
}


plot_list <- colnames(dt)[-1] %>% 
  map( ~ loop(df = dt, 
              x_var = colnames(dt)[1], 
              y_var = colnames(dt)[2], 
              f_var = .x))

# view all plots individually (not shown)
plot_list

Problems I encountered when ran this chunk of code:

1. Error: Discrete value supplied to continuous scale
2. Step ggsave didn't work. I would like to save each plot by the names of the changing columns.

CodePudding user response：

There are some minor issues with your code. You get the first error as you included the second column of your dataset (which is a categorical, i.e. discrete variable) in the loop. Second, title = .data[[f_var]] will not work. Simply use title = f_var to add the variable name as the title. Finally, you are trying to save an object called a which however is not defined in your code, i.e. you have to assign your plot to a variable a and to return the plot I added a return(a):

set.seed(123)

library(ggplot2)
library(purrr)

loop = function(df, x_var, y_var, f_var) {
  a <- ggplot(df, aes(x = .data[[x_var]], y = .data[[y_var]], fill = .data[[f_var]]))   
    geom_tile(color = "black")  
    scale_fill_gradient(low = "white", high = "blue")  
    geom_text(aes(label = .data[[f_var]]), color = "black", size = 4)  
    coord_fixed()  
    theme_minimal()  
    labs(x = "",
         y = "",
         fill = "R", # Want the legend title to be each of the column names that are looped
         title = f_var)
  
  ggsave(a, file = paste0("heatmap_", f_var,".png"), device = png, width = 15, height = 15, units = "cm")
  
  return(a)
}

plot_list <- colnames(dt)[-c(1, 2)] %>% 
  map( ~ loop(df = dt, 
              x_var = colnames(dt)[1], 
              y_var = colnames(dt)[2], 
              f_var = .x))

# view all plots individually (not shown)
plot_list[c(1, 5)]
#> [[1]]

#> 
#> [[2]]