Dear all,
Thanks very much for the replies and for the help.
This whole data set consists of about 7000 individuals who have had
multiple blood pressure measures taken over time so I just used one
individual as an example. I'm sorry if it looked like homework...it isn't.
Jim your solution wo
Here is one way of doing it:
> x
prochi date_1st_eventbp_date SBP DBP
108 ind_1 2010-06-24 2004-08-30 135 85
109 ind_1 2010-06-24 2009-11-23 160 80
110 ind_1 2010-06-24 2006-09-01 135 NA
111 ind_1 2010-06-24 2005-10-24 153 79
112 ind_1 2010-06-24 2002-11-21 150
Nathalie,
your method of sending sample data is fine.
dt = structure(list(prochi = c("ind_1", "ind_1", "ind_1",
"ind_1", "ind_1", "ind_1", "ind_1", "ind_1",
"ind_1", "ind_1"), date_1st_event = structure(c(14784,
14784, 14784, 14784, 14784, 14784, 14784, 14784, 14784, 14784
), class = "Date"), b
Hi Natalie,
By far the easiest thing to do is to convert the date to a special date
class. See as.POSIXct for example. I'm not sure that 14784 means, nor
what the data says in the bp_date column. Probably the two combine into
a specific date?
Once you've converted the columns into a POSIXct
Dear R help,
I have the following data frame:
structure(list(prochi = c("ind_1", "ind_1", "ind_1",
"ind_1", "ind_1", "ind_1", "ind_1", "ind_1",
"ind_1", "ind_1"), date_1st_event = structure(c(14784,
14784, 14784, 14784, 14784, 14784, 14784, 14784, 14784, 14784
), class = "Date"), bp_date = st
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