Plotting with Ggplot2: "Error: Discrete Value Supplied to Continuous Scale" on Categorical Y-Axis

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.

Violin plot error - Discrete value supplied to continuous scale

The error is caused by geom_vline(xintercept = 0) layer. Replace 0 with one of the values of your x, for example geom_vline(xintercept = "Left")

2 plots on one y axis - Error: Discrete value supplied to continuous scale

as per Stefan's comment:
The issue is that I map the numeric Temperature on color and in the second geom_line you map the character "red" on color.
Adding color="red" as an argument outside of aes() fixes the problem

ggplot2 error : Discrete value supplied to continuous scale

Evidently, you can't have different color aesthetics for two different geoms. As a workaround, use a fill aesthetic for the points instead. This means you have to use a point marker style that has a filled interior (see ?pch and scroll down for the available point styles). Here's a way to do that:

ggplot() + 
  geom_point(data=merged,aes(x = pauseMedian, y = numTotalPauses, fill = diff),
             pch=21, size=5, colour=NA) +
  geom_polygon(data = splineHull, 
               mapping=aes(x=pauseMedian, 
                           y=numTotalPauses, 
                           colour = microstyle),
               alpha=0) 

Adding colour=NA (outside of aes()), gets rid of the default black border around the point markers. If you want a colored border around the points, just change colour=NA to whatever colour you prefer.

Also see this thread from the ggplot2 Google group, discussing a similar problem and some workarounds.

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