ggplot2 0.8.1  (2008-12-12)
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New features

* new labs, xlab & ylab functions for easily modifying axis labels and legend titles
* qplot now guesses what geom you want based on the position aesthetics that you provide:
  * both x & y: scatterplot
  * only x: histogram
  * only y: scatterplot of seq_along(y) vs y
* scale_datetime: a first attempt at a scale for date time objects of class POSIXt

Aesthetic improvements

* legends should now work in cases where you have multiple layers the use the same geom and have different aesthetic mappings
* theme: new theme setting legend.key.size determines size of keys in legend
* theme: new theme setting plot.margins to control the plot margins
* tweaks to plot and legend layout

Other minor improvements

* geom_point warns if missing values present in data and not displayed on plot
* geom_smooth gives a more accurate warning when you have incorrectly specified the grouping
* geom_smooth will switch to an alternative smoothing method (mgcv::gam(y ~ s(x, bs = "cr"))), when there are more than 1000 observations
* layers gain a legend argument, which allow you to force the layer either into (TRUE) or out of (FALSE) the legend

Bug fixes

* coord_equal now calculates scales correctly again
* coord_flip: flips axes labels again too
* coord_trans fix bug where transformation incorrect
* facet_grid: fix bug where tick labels where being produced outside the range of the axes
* facet_wrap: fixed bug with ncol = 1 or nrow = 1
* facet_wrap: labels correctly clipped to axis ranges
* facet_wrap: labels will match panels even when factor levels are not in alphabetical order
* facet_wrap: now works when a layer doesn't contain every level of the faceting variables
* geom_abline should now work in a wider variety of situations
* geom_smooth now gives correct asymmetric standard errors with generalised linear models (thanks to Thierry Onkelinx)
* geom_vline and geom_hline now correctly transform their intercepts if the scale is transformed    
* geom_vline and geom_hline: now use xintercept and yintercept instead of intercept
* legend.position and legend.justification work again
* position_dodge now works for any number of elements with smaller widths, not just 2!
* scale_discrete_position: does a better job of calculating axis limits when plotting a mixture of continuous and discrete values (e.g. with geom_jitter)
* summary: tweaks to improve output
