ggkm: Kaplan Meier Plot from Matt Cooper...
In sagade/inf460: Misc tools for daily analysis

Kaplan Meier Plot from Matt Cooper (http://mcfromnz.wordpress.com/2012/05/05/kaplan-meier-survival-plot-with-at-risk-table-by-sub-groups/)

ggkm(sfit, sdiff = NULL, table = TRUE, returns = FALSE, plot = T,
  color = TRUE, xlabs = "Time", ylabs = "Survival Probability",
  xlims = c(0, max(sfit$time)), ylims = c(0, 1), ystratalabs = NULL,
  ystrataname = NULL, timeby = 100, main = "Kaplan-Meier Plot",
  pval = TRUE, pval.size = 4, probs = NULL, subs = NULL, ...)

`sfit`	a `survfit` object
`sdiff`	a `survdiff` object, used for compuation of exact p-values. If no survdiff object is given computation of p-values is based on the survfit object
`table`	logical: Create a table graphic below the K-M plot, indicating at-risk numbers?
`returns`	logical: if `TRUE`, return an arrangeGrob object
`plot`	logical: if `TRUE`, plot the graph
`color`	logical: if `TRUE`, use a colored scheme, otherwise black & white
`xlabs`	x-axis label
`ylabs`	y-axis label
`xlims`	the limit of x axis
`ylims`	the limit on the y axis
`ystratalabs`	The strata labels. `Default = levels(summary(sfit)$strata)`
`ystrataname`	The legend name. Default = "Strata"
`timeby`	numeric: control the granularity along the time-axis
`main`	plot title
`pval`	logical: add the pvalue to the plot?
`pval.size`	size of the pvalue in the plot. Default to 3
`probs`	numeric: vector with survail probabilities that will be marked by dotted lines, dfault to NULL
`subs`	default to NULL