While using ggplot2 to plot overalaid histograms on a dataset (bike sharing demand from kaggle) ->
ggplot(train, aes(x=temp, fill=day)) +
geom_histogram(binwidth=.5, alpha=.5, position="identity")
I am getting an error->
Error in unit(tic_pos.c, “mm”) : ‘x’ and ‘units’ must have length > 0
Why is it coming and how to remove it?