Epicurves updates

[nsbatra]

Epicurves page:

Add to all ggplot chunks that use a breaks = statement closed = "left", # count cases from start of breakpoint

Add bullet to explain its use, in Weekly Epicurve Example section

• We use closed = "left" in the geom_histogram() to ensure the date are counted in the correct bins

Edit the multi-line date labels to include labels = scales::label_date_short().

Remove one of the old examples using faceting. Edit the green faceting example to remove the facet panel border.

Also this is updated in the ggplot tip page section on date axis.

[arranhamlet]

This appears to have already been updated throughout