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Hist with Dates

3 messages · Dominic Roye, Christopher W. Ryan, Jeff Newmiller

Dominic Roye
# 
Hello R-Helpers,


I would like to generate the frequencies of dates (data.RData).

str(data)
 Date[1:43748], format: "2001-01-01" "2001-01-01" "2001-01-01" "2001-01-01"
...


test <- hist(data,"days",freq=T)
[1] 27 17 12 15  6  4  5 13  5 13 15  9  7 10 11 21 10 10  9 11 15  7 10
14


but the count is wrong, because i have only 9 times 01/01/2001 etc.
[1] "2001-01-01" "2001-01-01" "2001-01-01" "2001-01-01" "2001-01-01"
 [6] "2001-01-01" "2001-01-01" "2001-01-01" "2001-01-01"

"2001-01-02"
[11] "2001-01-02" "2001-01-02" "2001-01-02" "2001-01-02" "2001-01-02"
[16] "2001-01-02" "2001-01-02" "2001-01-02" "2001-01-02" "2001-01-02"
[21] "2001-01-03" "2001-01-03" "2001-01-03" "2001-01-03" "2001-01-03"
[26] "2001-01-03" "2001-01-03" "2001-01-03" "2001-01-03" "2001-01-03"



Now, when i give R the breaks.
seq(as.Date("31.12.2000",format="%d.%m.%Y"),as.Date("01.01.2012",format="%d.%m.%Y"),by=1)
[1] 12 15 17 12 15  6  4  5 13  5


In this case, neither get the right counts but limiting i get the correct
counts:
[1]  9 11 13  9  8


I hope someone can help me with this problem.


Thank you very much!!

Best regards,

Dominic
Christopher W. Ryan
# 
If all you want is frequencies, could you use table()?

dd <- c("2001-01-02", "2001-01-02",  "2001-01-02", "2001-01-02",
"2001-01-02", "2001-01-02", "2001-01-02", "2001-01-02", "2001-01-02",
"2001-01-03", "2001-01-03", "2001-01-03", "2001-01-03", "2001-01-03",
"2001-01-03", "2001-01-03", "2001-01-03", "2001-01-04", "2001-01-04")
ddd <- as.Date(dd)
str(ddd)
table(ddd)
as.numeric(table(ddd))

--Chris Ryan
SUNY Upstate Medical University
Binghamton, NY USA
On Tue, Jan 15, 2013 at 7:45 AM, Dominic Roye <dominic.roye at gmail.com> wrote:
Jeff Newmiller
# 
You should read the help for hist carefully:

?hist.Date

hist has very specific rules for applying breaks that are often different than tabulation (tapply or aggregate, with or without using the cut function first).
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Dominic Roye <dominic.roye at gmail.com> wrote: