R ggplot绘图报colours encodes as numbers must be positive错误求助

核心诱因 #

该报错由ggplot2语法使用错误导致：

• 映射数据框变量到图形属性（x轴、y轴、颜色、大小等）时，必须将映射逻辑放在aes()函数内部，你当前的代码直接在aes()外指定col=all$V1.y，R会将V1.y列的数值直接识别为原生颜色编码值。
• R的数值型颜色编码要求必须为正整数，对应内置调色板的位置，当你的大规模数据中V1.y列存在负数、零或非正整数时，就会触发该报错。

修正后的代码 #

## Load packages
library(tidyverse)
require(data.table)

## Read in data frames
m1<-fread("m1.csv", header = F)
m2<-fread("m2.csv", header = F)
L<-fread("l.csv", header = F)
LP<-fread("LP.csv", header = F)

## Get rate by taking m1 from m2
rate<-m1[1,]-m2[1,] ### subtract p1 rate from p2

## Transpose the data frame
t_rate <- transpose(rate) 

## Create row ID's to merge data frames
L$row_num <- seq.int(nrow(L))  
t_rate$row_num <- seq.int(nrow(t_rate)) 

all<-merge(L, t_rate, by = "row_num") ## merge the dataframes based on their ID

## Get rid of ID now we don't need it
all$row_num=NULL

## 修正后的绘图代码
ggplot(all, aes(x = V1.x, y = V2, col = V1.y)) +
  geom_point(size = 0.1) +
  geom_point(data = LP, aes(x = V1, y = V2), size = 1)

补充说明：如果需要为第二组LP点设置固定颜色，可在对应geom_point的aes()外添加颜色参数，例如设置为黑色可写为geom_point(data = LP, aes(x = V1, y = V2), size = 1, col = "black")

内容的提问来源于stack exchange，提问作者Sophie Williams