View source: R/make.time.factor.r
make.time.factor | R Documentation |
Create a new dataframe with time-varying dummy variables from a time-varying factor variable. The time-varying dummy variables are named appropriately to be used as a set of time dependent individual covariates in a parameter specification
make.time.factor(x, var.name, times, intercept = NULL, delete = TRUE)
x |
dataframe containing set of factor variables with names composed of var.name prefix and times suffix |
var.name |
prefix for variable names |
times |
numeric suffixes for variable names |
intercept |
the value of the factor variable that will be used for the intercept |
delete |
if TRUE, the origninal time-varying factor variables are removed from the returned dataframe |
An example of the var.name and times is var.name="observer", times=1:5. The code expects to find observer1,...,observer5 to be factor variables in x. If there are k unique levels (excluding ".") across the time varying factor variables, then k-1 dummy variables are created for each of the named factor variables. They are named with var.name, level[i], times[j] concatenated together where level[i] is the name of the facto level i. If there a m times then the new data set will contain m*(k-1) dummy variables. If the factor variable includes any "." values these are ignored because they are used to indicate a missing value that is paired with a missing value in the encounter history. Note that it will create each dummy variable for each factor even if a particular level is not contained within a factor (eg observers 1 to 3 used but only 1 and 2 on occasion 1).
x: a dataframe containing the original data (with time-varying factor variables removed if delete=TRUE) and the time-varying dummy variables added.
Jeff Laake
# see example in weta
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