如何使用ggplot自动绘制多个数据集？

Question

I have a data file that looks like this:

X1_axis Y1_axis X2_axis Y2_axis

values values values values

X1_axis is the coordinate of axis number one and Y1_axis are the data number one to be represented on the y_axis and so on.

One solution is:

require(ggplot2)
p + geom_line(aes(x = X1_axis, y = Y1_axis, col = "plot 1")) + 
geom_line(aes(x = X2_axis, y = Y2_axis, col = "plot 2"))

Is there a shorter and better way to do this? If I have 20 of such pairs plotting them using this method takes a lot of typing and the codes looks ugly.

Answer 1

This should do the job using dplyr to create some new variables (mutate), tidyr to transpose the data (gather and spread) and stringr to grab the number out of the axis name (str_extract).

library(dplyr)
library(tidyr)
library(stringr)
library(ggplot2)

df <- data.frame(x1_axis = runif(5),
             y1_axis = runif(5),
             x2_axis = runif(5),
             y2_axis = runif(5)
)

df_transpose <- df %>%
  mutate(observation_number = row_number()) %>%  #Add an observation number column
  gather(axis, value, -observation_number) %>%  #flatten the data
  mutate(group_var = str_extract(axis, "[0-9]+")) %>%  #grab numeric part of the axis name to use as a grouping variable
  mutate(axis = gsub('[0-9]+', '', axis)) %>%  #remove numbers from the axis names
  spread(axis, value) %>% #pivot the axis names back to columns again
  arrange(group_var, observation_number)  #tidy up

ggplot(data = df_transpose, aes(x = x_axis, y = y_axis, group = group_var)) +
       geom_line()