stratSurvData: Stratify patient survival data
In n8thangreen/HESmanip: Hospital length of stay data preprocessing and analysis

1	stratSurvData(survData, survDataCol)

`survData`	patient records data.
`survDataCol`	vector of whole column by which to stratify by.

N Green

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--	or do  help(data=index)  for the standard data sets.

## The function is currently defined as
function (survData, survDataCol) 
{
    Glevels <- nlevels(survDataCol)
    Gnames <- levels(survDataCol)
    survDataStrat <- list()
    for (i in 1:Glevels) {
        survDataStrat[[i]] <- survData[survDataCol == Gnames[i], 
            ]
        survDataStrat[[i]] <- survDataStrat[[i]][order(survDataStrat[[i]]$infstatus), 
            ]
    }
    names(survDataStrat) <- Gnames
    survDataStrat
  }