date.format looks like an option that's actually not implemented

[tchevri]

Hi,
First of all thank you for the awesome package - been using for a very long time. Really much appreciated.
Now, I hate to post, because chances are the issue is with me, rather than with the code, so i can only apologize in advance if i am the one mistaken.

Punchline: I have been trying to change the x-axis date format. Looking through the doc, it looks like date.format = NULL is the option that needs to be changed to achieve the desired result. Changing this option does not lead to any change in the output.

This said, after searching SO intensively and resorting to looking at the source code for https://github.com/cran/PerformanceAnalytics/blob/master/R/chart.TimeSeries.builtin.R, it looks to me that the date.format option is actually never really used. There is a whole section that's definitely setting it if it's not set specifically set at the onset as a function parameter, see lines 49-63.

However, to my somewhat surprise, the call to plot.xts does not use this parameter! See lines 95-103...

As a matter of fact, i searched the entire file and that parameter never gets used anywhere. Hence why i think something's off... and this post!

many thanks
thomas