Search code examples
rggplot2linescatter-plotcartesian-coordinates

Tracing lines between points in a scatterplot using ggplot2 in R

You can download the data here

enter image description here

Each row represents one object that can be found in different parts, as shown in the XY coordinates (x1,y1; x2,y2;...; xn,yn). In this dataset, the rows with more points are "1", "16" and "18", with 4 points (coordinates) each.

I would like to scatterplot all of those XY coordinates using ggplot2, and to trace lines between points in each row separately.

Solution

  • I finally did it manually by running several codes:

    First, I removed columns with no data:

    Refits_H <- within(Refits_H, {
  Unit <- NULL  
  x5 <- NULL
  x6 <- NULL
  x7 <- NULL
  x8 <- NULL
  x9 <- NULL
  x10 <- NULL
  x11 <- NULL
  y5 <- NULL
  y6 <- NULL
  y7 <- NULL
  y8 <- NULL
  y9 <- NULL
  y10 <- NULL
  y11 <- NULL 
})

    Second, I reorder the rows and the columns:

    Refits_H <- with(Refits_H, Refits_H[order(y4, y3, y2, y1, decreasing=FALSE),])
Refits_H <- Refits_H[c("x4","y4","x3","y3","x2","y2","x1","y1")]

    And finally I answered my own question my running this code:

    library(tidyverse)
library(dplyr)

Refits_H_trans <- gather(Refits_H, xy, val) %>% 
    mutate(coord = substr(xy, 1, 1),
           pair = parse_number(xy)) %>% 
    group_by(xy) %>% 
    mutate(sample = 1:n()) %>% 
    ungroup() %>% 
    select(-xy) %>% 
    spread(coord, val) %>% 
    filter(!is.na(x) & !is.na(y))