如何为列表中的每个 dataframe 创建 ggplot 并将它们导出到 R 中？

Question

I have a list of dataframes of data separated with different names (eg, 57-block8, 58-block8, 59-block8, etc.). I wanna plot graphs for each of the split table using the same variables (ie, BIN_END_TIME on the x-axis and AVERAGE_PUPIL_SIZE_BIN on the y-axis), and have each plot named with the respective names of the dataframe. I also wanna draw some x-intercept vertical lines on each plot derived using the value of the last row of the BIN_END_TIME column. Many thanks!

Answer 1

Setting up some data to provide as an example:

iris2 <- iris[,-5]
iris_list <- split(iris2, iris$Species)
str(iris_list)
List of 3
 $ setosa    :'data.frame': 50 obs. of  4 variables:
  ..$ Sepal.Length: num [1:50] 5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ...
  ..$ Sepal.Width : num [1:50] 3.5 3 3.2 3.1 3.6 3.9 3.4 3.4 2.9 3.1 ...
  ..$ Petal.Length: num [1:50] 1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ...
  ..$ Petal.Width : num [1:50] 0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ...
 $ versicolor:'data.frame': 50 obs. of  4 variables:
  ..$ Sepal.Length: num [1:50] 7 6.4 6.9 5.5 6.5 5.7 6.3 4.9 6.6 5.2 ...
  ..$ Sepal.Width : num [1:50] 3.2 3.2 3.1 2.3 2.8 2.8 3.3 2.4 2.9 2.7 ...
  ..$ Petal.Length: num [1:50] 4.7 4.5 4.9 4 4.6 4.5 4.7 3.3 4.6 3.9 ...
  ..$ Petal.Width : num [1:50] 1.4 1.5 1.5 1.3 1.5 1.3 1.6 1 1.3 1.4 ...
 $ virginica :'data.frame': 50 obs. of  4 variables:
  ..$ Sepal.Length: num [1:50] 6.3 5.8 7.1 6.3 6.5 7.6 4.9 7.3 6.7 7.2 ...
  ..$ Sepal.Width : num [1:50] 3.3 2.7 3 2.9 3 3 2.5 2.9 2.5 3.6 ...
  ..$ Petal.Length: num [1:50] 6 5.1 5.9 5.6 5.8 6.6 4.5 6.3 5.8 6.1 ...
  ..$ Petal.Width : num [1:50] 2.5 1.9 2.1 1.8 2.2 2.1 1.7 1.8 1.8 2.5 ...

We have a list of 3 similar data frames. The bind_rows() function from dplyr easily combines them together, and giving a name to the .id argument includes the name given to each data frame as an additional variable:

iris_keys <- dplyr::bind_rows(iris_list, .id = "keys")

head(iris_keys)
    keys Sepal.Length Sepal.Width Petal.Length Petal.Width
1 setosa          5.1         3.5          1.4         0.2
2 setosa          4.9         3.0          1.4         0.2
3 setosa          4.7         3.2          1.3         0.2
4 setosa          4.6         3.1          1.5         0.2
5 setosa          5.0         3.6          1.4         0.2
6 setosa          5.4         3.9          1.7         0.4

You can now use that variable as a name for the facetting for your chart:

library(ggplot2)
ggplot(iris_keys, aes(x = Sepal.Length, y = Petal.Length)) + 
  geom_point() +
  facet_wrap(vars(keys))

EDIT: If you want to create a list of plots, here's an example on achieving this:

library(purrr)

myplots <- map(iris_list, ~ ggplot(.x, aes(x = Sepal.Length, y = Petal.Length)) + 
      geom_point())

And the following line will save the plots to disk:

iwalk(myplots, ~ ggsave(glue::glue("{.y}.png"), .x, device = "png"))