CODEWITHSUNDEEP
rggplot2
blue-sky
blue-sky

Reputation: 53916

Unable to plot multiple day/values using ggplot

Using ggplot I am trying to plot two lines of values. So var0 has values 49,5,20 for "Monday" , "Tuesday" , "Wednesday" and var1 has values 49,1,20 for "Monday" , "Tuesday" , "Wednesday"

Here is the code : 

test_data <- data.frame(
var0 = c(49, 5, 20),
var1 = c(49, 1, 10),
days = c("Monday" , "Tuesday" , "Wednesday"))

ggplot(test_data, days)
geom_line(y = var0, colour = "var0")
geom_line(y = var1, colour = "var1")

here are the errors : 

> ggplot(test_data, days)
Error in inherits(mapping, "uneval") : object 'days' not found
> geom_line(y = var0, colour = "var0")
Error in do.call("layer", list(mapping = mapping, data = data, stat = stat,  : 
  object 'var0' not found
> geom_line(y = var1, colour = "var1")
Error in do.call("layer", list(mapping = mapping, data = data, stat = stat,  : 
  object 'var1' not found

Am I setting up the data correctly ?

Upvotes: 1

Views: 2353

Answers (1)

Didzis Elferts
Didzis Elferts

Reputation: 98599

There were several mistakes in your code - x and y values should be put inside the aes() call and then there was missing + sign between ggplot() and geom_line() calls.

If you need to plot two groups of y values I would suggest, first, melt your data and then plot melted data frame. With melted data you will need only one geom_line() call and you can set color for each line according to variable that will be shown in legend.

library(reshape2)
test_data2<-melt(test_data,id.vars="days")
test_data2
       days variable value
1    Monday     var0    49
2   Tuesday     var0     5
3 Wednesday     var0    20
4    Monday     var1    49
5   Tuesday     var1     1
6 Wednesday     var1    10
ggplot(test_data2,aes(days,value,color=variable,group=variable))+geom_line()

enter image description here

Upvotes: 4

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