Ggplot2 Error:Discrete Value Supplied to Continuous Scale

Plotting with ggplot2: Error: Discrete value supplied to continuous scale on categorical y-axis

As mentioned in the comments, there cannot be a continuous scale on variable of the factor type. You could change the factor to numeric as follows, just after you define the meltDF variable.

meltDF$variable=as.numeric(levels(meltDF$variable))[meltDF$variable]

Then, execute the ggplot command

  ggplot(meltDF[meltDF$value == 1,]) + geom_point(aes(x = MW, y =   variable)) +
     scale_x_continuous(limits=c(0, 1200), breaks=c(0, 400, 800, 1200)) +
     scale_y_continuous(limits=c(0, 1200), breaks=c(0, 400, 800, 1200))

And you will have your chart.

Hope this helps

How to fix error in R: Discrete value supplied to continuous scale?

The error is telling you that you have a categorical variable where a continuous variable should be. You don't mention which variable it is, which usually R tells you. It might help if you paste the entire error. However, if R is reading it incorrectly and it actually is a continuous variable, you can use this: as.numeric(variable_name). If it is actually a categorical variable, then something is wrong in the approach, ie you're using the wrong chart type.

Digging into your code, you have Stations as class ="factor". Try changing this to numeric.

Error: Continuous value supplied to discrete scale in default data set example mtcars and ggplot2

Yeah, I was able to fix it by converting the color and shape aesthetics to factors:

ggplot(mtcars, aes(x=wt, y=mpg, color=as.factor(cyl), shape=as.factor(cyl))) +
  geom_point() + 
  geom_smooth(method=lm, se=FALSE, fullrange=TRUE)+
  scale_shape_manual(values=c(3, 16, 17))+ 
  scale_color_manual(values=c('#999999','#E69F00', '#56B4E9'))+
  theme(legend.position="top")

Error: Discrete value supplied to continuous scale problem

Since your year column is of class character, ggplot is giving out the error

Error: Discrete value supplied to continuous scale

You need to add the following line to make it work.

scale_x_discrete()

Your code will look like this:

ggp <- ggplot(yearlywindhcgasbio, aes(year)) + 
  geom_line(aes(y = Wind, (size = 1.5)), group = 1) + 
  geom_line(aes(y = Hard_coal), group = 2) + 
  geom_line(aes(y = Gas), group = 3) + 
  geom_line(aes(y = Bio), group = 4) +
  scale_x_discrete()

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