"Error: Mapping should be created with `aes()` or `aes_()`."

Question

I'm trying to build a simple histogram with ggplot2 package in R. I'm loading my data from a csv file and putting 2 of the columns together in a data frame, like this:

df = data.frame(sp = data$species, cov = data$totalcover) 

sp is recognised as a factor of 23 levels (my number of lines) and cov as 23 numbers. Then, to build the histogram, I'm executing this:

ggplot(df, aes(df$sp, df$cov) + geom_histogram()) 

However, R returns the error: "Error: Mapping should be created with aes() or aes_()."

How is this possible if I'm already using aes? Is it maybe related with the type of the values?

Answer 1

I had the same error, even if I was using aes(). So I used "mapping" before aes()

ggplot()+ geom_boxplot (df, mapping = aes(x= sp, y= cov)) 

Answer 2

Two mistakes:

1. Brackets have to be closed after ggplot and calling histogram comes after
2. you specify your data set when you call ggplot on df. Therefore there is no need to add df$sp. sp is enough.

This code should work (if there is nothing wrong with your data):

    ggplot(df, aes(sp, cov)) + geom_histogram()