R help - May 2009 - using chron vector with boxplot

Hi,

 

I'm having trouble using dates (created using library(chron)) as
groupings for a boxplot.  I have 10 repeat measurements of a variable
within an individual day.  The measurements were done over 10 days.  I
would like to plot the measurements as a box and wisker plot (using
boxplot or something similar) where the days (as chron object) would be
the grouping and the repeated measurements of the variable make up the
box and wisker plot.  I would like the spacing of the individual
boxplots to reflect the time between measurements:

 

Example using random numbers:

 

### Create date vector of measurement dates

library(chron)

time=c(39083, 39085, 39095, 39096, 39103, 39104, 39105, 39110, 39113,
39120);

orig =chron("01/01/1900")

date = orig + time-2;

 

###  Data for B and W plot

data = data.frame();

mean=rnorm(10, mean=0, sd=1);

for(i in 1:10){data[1:10,i] =rnorm(10, mean=mean[i], sd=1)};

 

### Plot

boxplot(data, range=0);  # works, but doesn't reflect the different time
intervals between measurements dates!

boxplot(data~date, range=0) # tried using formula, gives error:

            Error in model.frame.default(formula = data ~ date) : 

             invalid type (list) for variable 'data'

 

Not sure what to try next.  Any suggestions?

 

Thanks,

ken

 

kat215@psu.edu

 


	[[alternative HTML version deleted]]

Try this:

  boxplot(as.matrix(data) ~ as.Date(date), cex.axis = 0.5, las = 2)

or if all the dates are in the same year and month as they are here
then you might want to just display the day of the month:

  boxplot(as.matrix(data) ~ month.day.year(date)$day)


On Sun, May 31, 2009 at 1:45 PM, Kenneth Takagi <kat215 at psu.edu>
wrote:
> Hi,
>
>
>
> I'm having trouble using dates (created using library(chron)) as
> groupings for a boxplot. ?I have 10 repeat measurements of a variable
> within an individual day. ?The measurements were done over 10 days. ?I
> would like to plot the measurements as a box and wisker plot (using
> boxplot or something similar) where the days (as chron object) would be
> the grouping and the repeated measurements of the variable make up the
> box and wisker plot. ?I would like the spacing of the individual
> boxplots to reflect the time between measurements:
>
>
>
> Example using random numbers:
>
>
>
> ### Create date vector of measurement dates
>
> library(chron)
>
> time=c(39083, 39085, 39095, 39096, 39103, 39104, 39105, 39110, 39113,
> 39120);
>
> orig =chron("01/01/1900")
>
> date = orig + time-2;
>
>
>
> ### ?Data for B and W plot
>
> data = data.frame();
>
> mean=rnorm(10, mean=0, sd=1);
>
> for(i in 1:10){data[1:10,i] =rnorm(10, mean=mean[i], sd=1)};
>
>
>
> ### Plot
>
> boxplot(data, range=0); ?# works, but doesn't reflect the different
time
> intervals between measurements dates!
>
> boxplot(data~date, range=0) # tried using formula, gives error:
>
> ? ? ? ? ? ?Error in model.frame.default(formula = data ~ date) :
>
> ? ? ? ? ? ? invalid type (list) for variable 'data'
>
>
>
> Not sure what to try next. ?Any suggestions?
>
>
>
> Thanks,
>
> ken
>
>
>
> kat215 at psu.edu
>
>
>
>
> ? ? ? ?[[alternative HTML version deleted]]
>
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