Building a histogram in ggplot2 leads to a memory error (a total of 418 data points)

Question

I am trying to build a histogram with two datasets using ggplot2. My dataset has 418 values ​​to plot, with two groups of data (so there will be two sets of color bars on my histogram). Annoyingly, I cannot reproduce the iris dataset issue:

 library(ggplot2) ggplot(iris, aes(x=iris[,1], fill=iris[,5])) + geom_histogram(binwidth=.5,alpha=.5) 

This creates a subtle histogram. When I try this according to my data, I get:

 Error : cannot allocate vector of size 4.0 Gb In addition: Warning messages: 1: In anyDuplicated.default(breaks) : Reached total allocation of 16366Mb: see help(memory.size) 2: In anyDuplicated.default(breaks) : Reached total allocation of 16366Mb: see help(memory.size) 3: In anyDuplicated.default(breaks) : Reached total allocation of 16366Mb: see help(memory.size) 4: In anyDuplicated.default(breaks) : Reached total allocation of 16366Mb: see help(memory.size) Error in UseMethod("scale_dimension") : no applicable method for 'scale_dimension' applied to an object of class "NULL" 

I have 16 GB of memory, so creating a patch with 418 data points should not be a problem.

Any help is greatly appreciated.

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It turns out that my data will still not be displayed, even if it refers to column names. I think this is due to the data range. After the log converts the data, graph the histogram. It seems that ggplot2 or R as a whole does not like the range 1-165476109, which is understandable ...

Answer 1

Your code should look like this:

 ggplot(iris, aes(x=Sepal.Length, fill=Species)) + geom_histogram(binwidth=.5,alpha=.5) 

The reason is that the arguments inside aes() are evaluated in your data environment. This means that your mapping should point to the column names in your data, i.e. x=Sepal.Length ).

When you write the aes() call the way you did, you try to tell ggplot match 150 different variables with x and likewise match 150 different variables with fill - this is obviously not what you meant.