R: Connecting Points in Arbitrary Order [duplicate]

Question

I am working with the R programming language.

I generated the following random data set in R and made a plot of these points:

library(ggplot2)

set.seed(123)

x_cor = rnorm(5,100,100)
y_cor = rnorm(5,100,100)


my_data = data.frame(x_cor,y_cor)

      x_cor     y_cor
1  43.95244 271.50650
2  76.98225 146.09162
3 255.87083 -26.50612
4 107.05084  31.31471
5 112.92877  55.43380


ggplot(my_data, aes(x=x_cor, y=y_cor)) + geom_point() + ggtitle("Travelling Salesman Example")

Suppose I want to connect these dots together in the following order: 1 with 3, 3 with 4, 4 with 5, 5 with 2, 2 with 1

I can make a new variable that contains this ordering:

my_data$order = c(3, 1, 4, 5, 2)

Is it possible to make this kind of graph using ggplot2?

I tried the following code - but this connects the points based on the order they appear in, and not the custom ordering:

ggplot(my_data, aes(x = x_cor, y = y_cor)) +
    geom_path() +
    geom_point(size = 2)

I could probably manually re-shuffle the dataset to match this ordering - but is there an easier way to do this?

In the past, I have made these kind of graphs using "igraph" - but is it possible to make them with ggplot2? Can someone please show me how to do this?

Thanks!

Answer 1

You can order your data like so:

my_data$order = c(1, 5, 2, 3, 4)

ggplot(my_data[order(my_data$order),], aes(x = x_cor, y = y_cor)) +
  geom_path() +
  geom_point(size = 2)

If you want to close the path, use geom_polygon:

ggplot(my_data[order(my_data$order),], aes(x = x_cor, y = y_cor)) +
  geom_polygon(fill = NA, color = "black") +
  geom_point(size = 2)