Here is sample data where ID is a categorical variable.

ID <- c(12, 34, 560, 45, 235)
W1 <- c(0, 5, 7, 6, 0)
W2 <- c(7, 8, 9, 5, 2)
W3 <- c(0, 0, 3, 5, 9)
 
df <- data.frame(ID, W1, W2, W3)
df$ID <- as.factor(df$ID)

I want to draw five bar plots for each of these IDs using the frequency data for the three weeks W1:W3. In the actual dataset, I have 30 weeks and around 150 IDs, hence the intention here is to do this efficiently. Nothing fancy, but ggplot would be ideal as I would need to manipulate some aesthetics.

How to do this using loop and save the images in one file(pdf)?

Thanks for your help!

CodePudding user response：

This sort of problem is usually a data reformating problem. See reshaping data.frame from wide to long format. After reshaping the data, the plot is faceted by ID, avoiding loops.

library(ggplot2)

ID <- c(12, 34, 560, 45, 235)
W1 <- c(0, 5, 7, 6, 0)
W2 <- c(7, 8, 9, 5, 2)
W3 <- c(0, 0, 3, 5, 9)

df <- data.frame(ID, W1, W2, W3)
df$ID <- as.factor(df$ID)
df[-1] <- lapply(df[-1], as.integer)

df |>
  tidyr::pivot_longer(-ID, names_to = "Week", values_to = "Frequency") |>
  ggplot(aes(Week, Frequency, fill = Week))  
  geom_col()  
  scale_y_continuous(breaks = scales::pretty_breaks())  
  facet_wrap(~ ID)  
  theme_bw(base_size = 16)

^{Created on 2022-09-30 with reprex v2.0.2}

Edit

If there is a mix of week numbers with 1 and 2 digits, the lexicographic order is not the numbers' order. For instance, after W1 comes W11, not W2. Package stringr function str_sort sorts by numbers when argument numeric = TRUE.
In the example below I reuse the data changing W2 to W11. The correct bars order should therefore be W1, W3, W11.

library(ggplot2)
library(stringr)

ID <- c(12, 34, 560, 45, 235)
W1 <- c(0, 5, 7, 6, 0)
W11 <- c(7, 8, 9, 5, 2)
W3 <- c(0, 0, 3, 5, 9)

df <- data.frame(ID, W1, W11, W3)
df$ID <- as.factor(df$ID)
df[-1] <- lapply(df[-1], as.integer)

df |>
  tidyr::pivot_longer(-ID, names_to = "Week", values_to = "Frequency") |>
  dplyr::mutate(Week = factor(Week, levels = str_sort(unique(Week), numeric = TRUE))) |>
  ggplot(aes(Week, Frequency, fill = Week))  
  geom_col()  
  scale_y_continuous(breaks = scales::pretty_breaks())  
  facet_wrap(~ ID)  
  theme_bw(base_size = 16)

^{Created on 2022-10-01 with reprex v2.0.2}