问题
I want to write a function that takes a dataframe, and graphs all the columns in that dataframe as histograms.
For a dataframe whose column names I know beforehand, I can write
qplot(colname1, data=df, geom='histogram')
qplot(colname2, data=df, geom='histogram')
...
but I want to do this generically, so that I can use the name of the column as a string "colname1".
In other words, how to write
plot_histogram_of_column <- function(df, colname) {
# qplot(colname, data=df, geom='histogram') won't work
}
回答1:
Use ggplot and aes_string. Something like this:
ggplot(data = df, aes_string(x = colname)) + geom_histogram()
aes_string was written precisely for this purpose.
来源：https://stackoverflow.com/questions/8570855/how-to-convert-dataframe-column-names-from-strings-into-arguments-suitable-for