Splines

All of the code below produces the same picture.  It does spline interpolation between the values.

```{r}
data(diamonds, package="ggplot2")
set.seed(123)
diamonds.samp <- diamonds[sample(1:dim(diamonds)[1],100),]
columns <- c(1, 5:10)
ggparcoord(diamonds.samp, columns, groupColumn = 2, splineFactor = TRUE)
ggparcoord(diamonds.samp, columns, groupColumn = 2, splineFactor = 3)
splineFactor <- length(columns) * 3
ggparcoord(diamonds.samp, columns, groupColumn = 2, splineFactor = I(splineFactor))
```

![screenshot 2014-11-16 15 21 34](https://cloud.githubusercontent.com/assets/93231/5063029/4ab23b84-6da4-11e4-96dd-5a86ac852b29.png)