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## ---- echo = FALSE, message = FALSE---------------------------------------------------------------
require(data.table)
knitr::opts_chunk$set(
comment = "#",
error = FALSE,
tidy = FALSE,
cache = FALSE,
collapse = TRUE)
## ----echo = FALSE---------------------------------------------------------------------------------
options(width = 100L)
## -------------------------------------------------------------------------------------------------
s1 <- "family_id age_mother dob_child1 dob_child2 dob_child3
1 30 1998-11-26 2000-01-29 NA
2 27 1996-06-22 NA NA
3 26 2002-07-11 2004-04-05 2007-09-02
4 32 2004-10-10 2009-08-27 2012-07-21
5 29 2000-12-05 2005-02-28 NA"
DT <- fread(s1)
DT
## dob stands for date of birth.
str(DT)
## -------------------------------------------------------------------------------------------------
DT.m1 = melt(DT, id.vars = c("family_id", "age_mother"),
measure.vars = c("dob_child1", "dob_child2", "dob_child3"))
DT.m1
str(DT.m1)
## -------------------------------------------------------------------------------------------------
DT.m1 = melt(DT, measure.vars = c("dob_child1", "dob_child2", "dob_child3"),
variable.name = "child", value.name = "dob")
DT.m1
## -------------------------------------------------------------------------------------------------
dcast(DT.m1, family_id + age_mother ~ child, value.var = "dob")
## -------------------------------------------------------------------------------------------------
dcast(DT.m1, family_id ~ ., fun.agg = function(x) sum(!is.na(x)), value.var = "dob")
## -------------------------------------------------------------------------------------------------
s2 <- "family_id age_mother dob_child1 dob_child2 dob_child3 gender_child1 gender_child2 gender_child3
1 30 1998-11-26 2000-01-29 NA 1 2 NA
2 27 1996-06-22 NA NA 2 NA NA
3 26 2002-07-11 2004-04-05 2007-09-02 2 2 1
4 32 2004-10-10 2009-08-27 2012-07-21 1 1 1
5 29 2000-12-05 2005-02-28 NA 2 1 NA"
DT <- fread(s2)
DT
## 1 = female, 2 = male
## -------------------------------------------------------------------------------------------------
DT.m1 = melt(DT, id = c("family_id", "age_mother"))
DT.m1[, c("variable", "child") := tstrsplit(variable, "_", fixed = TRUE)]
DT.c1 = dcast(DT.m1, family_id + age_mother + child ~ variable, value.var = "value")
DT.c1
str(DT.c1) ## gender column is character type now!
## -------------------------------------------------------------------------------------------------
colA = paste("dob_child", 1:3, sep = "")
colB = paste("gender_child", 1:3, sep = "")
DT.m2 = melt(DT, measure = list(colA, colB), value.name = c("dob", "gender"))
DT.m2
str(DT.m2) ## col type is preserved
## -------------------------------------------------------------------------------------------------
DT.m2 = melt(DT, measure = patterns("^dob", "^gender"), value.name = c("dob", "gender"))
DT.m2
## -------------------------------------------------------------------------------------------------
## new 'cast' functionality - multiple value.vars
DT.c2 = dcast(DT.m2, family_id + age_mother ~ variable, value.var = c("dob", "gender"))
DT.c2
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