Secondary and Multiple x and y axis

Hello,

searched repository and documentation for secondary x & y axis, @has2k1 you mentioned in #63 , "When Matplotlib ships the constraint layout manager, I'll look into adding secondary axes functionality."

Do you have any idea what the approx timeframe for this is, months or quarters away?

For the finance guys having not only secondary but multiple x & y axes is extremely handy, which is something that users of bloomberg and reuters eikon are familiar with, and has been a major problem for excel users as they still haven't managed to even introduce a tertiary, or let alone even more levels in axes options, people have to index data if they need to compare more than 2 different time series still even in excel 2016 as we all know, which is a time consuming pain.

e.g.

(ggplot(df, aes(x1="", x2="", x3="", ...  , y1="" y2="", y3="", ... ))
+ scale_x1_datetime(breaks=date_breaks('1 year'), 
+ scale_x2_datetime(breaks=date_breaks('1 quarter'),
+ scale_x3_datetime(breaks=date_breaks('1 month'), 
+ geom_line(aes(y1='US'), color='#00355F', size=1)
+ geom_line(aes(y2='Turkey'), color='#2494EA', size=1)
+ geom_line(aes(y3='Australia'), color='#0222FF', size=1)
+ labs(x1="", x2="", x3="", y1="" y2="", y3="")

matplot example code: multiple_yaxis_with_spines.py
https://matplotlib.org/gallery/ticks_and_spines/multiple_yaxis_with_spines.html

Kind Regards,

Start by reviewing issue #63 and the referenced constraint layout manager discussion. Compare the requested secondary and multiple-axis behavior with the linked Matplotlib example, multiple_yaxis_with_spines.py. Done would require an agreed design and implementation scope for multiple x and y axes in plotnine.