Hi David
Are you having problems getting the data in or further down the track
If it is dBase III or IV (opens in excel with the appropriate excel
extension filter) you can use
library(foreign)
data <- read.dbf("d:/Cic/dbf/dsw3.dbf")
> str(data)
'data.frame': 43730 obs. of 8 variables:
$ DATE : Date, format: "1889-01-01" "1889-01-02"
"1889-01-03"
"1889-01-04" ...
$ DSW1 : num 2.38 2.21 2.66 2.12 2.11 2.1 2.09 2.08 2.08 2.07 ...
$ DSW2 : num 24.3 22.3 22 21.1 20.4 ...
$ DSW3 : num 36.6 34.6 33.7 31 27.7 ...
$ DSW4 : num 57.9 57.5 57.5 57.3 57.2 ...
$ DSW5 : num 58 58 58 58 58 ...
$ DSW : num 63.2 59.1 58.3 54.2 50.2 ...
$ JULIAN: int 1 2 3 4 5 6 7 8 9 10 ...
- attr(*, "data_types")= chr "D" "N"
"N" "N" ...
Convert to date format by converting the posix to date ? as.Date (I
have forgotton-- do not use posix often)
Then
xyplot(DSW1 ~ DATE, data, type = "l",aspect=0.25)
aspect added due to 43K+ records
or by years - short version
xyplot(DSW1 ~ JULIAN|format(DATE,"%Y"), data, type = "l")
This is one with a combined character of date and time
ln1 = read.dbf("d:/tmp/ln1.dbf",as.is=T)
> str(ln1)
'data.frame': 2216 obs. of 7 variables:
$ DATE : Date, format: "2004-04-15" "2004-04-15"
"2004-04-15"
"2004-04-15" ...
$ TIME : chr "19:40:00" "19:45:00" "19:50:00"
"19:55:00" ...
$ TD_01: num 15.5 15.3 15.1 15.1 15.1 14.9 14.9 14.6 14.6 14.4 ...
$ TD_03: num 21.9 21.9 21.7 21.7 21.7 21.5 21.5 21.5 21.5 21.2 ...
$ SR_04: num 0 0 0 0 0 0 0 0 0 0 ...
$ RG_05: num 0 0 0 0 0 0 0 0 0 0 ...
$ WR_06: num 0.4 0.3 0.4 0.3 0.4 0.3 0.3 0.3 0.4 0.3 ...
- attr(*, "data_types")= chr "D" "C"
"N" "N" ...
> ldt <- paste(ln1[,1],ln1[,2])
> head(ldt)
[1] "2004-04-15 19:40:00" "2004-04-15 19:45:00"
"2004-04-15 19:50:00"
"2004-04-15 19:55:00" "2004-04-15 20:00:00" "2004-04-15
20:05:00"
> ld.date = as.Date(ldt, "%Y-%m-%d %H:%M:%S")
> head(ld.date)
[1] "2004-04-15" "2004-04-15" "2004-04-15"
"2004-04-15" "2004-04-15"
"2004-04-15"
str(ld.date)
Date[1:2216], format: "2004-04-15" "2004-04-15"
"2004-04-15"
"2004-04-15" "2004-04-15"
As usual the more info provided the more appropriate the response
Version 2.14.1
HTH
Duncan
Duncan Mackay
Department of Agronomy and Soil Science
University of New England
ARMIDALE NSW 2351
Email home: mackay at northnet.com.au
At 12:27 1/04/2012, you wrote:>Hello,
>
>I am loading a DBF file into R via JGR and am having trouble creating small
>multiple histograms on a date variable. Hist() handles the variable
>correctly. But I've been unable to work with lattice or ggplot2 despite
>trying format() and as.POSIXct(). Dates are in the format
"2010-05-15" and
>the grouping variable is categorical. I'd appreciate it if someone would
>provide an example.
>
>Thank you,
>-david
>
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>and provide commented, minimal, self-contained, reproducible code.