[R] reducing distances between tickmarks

[Dimitri Liakhovitski]

Thanks a lot, David. It helped.
Here is my solution:

Instead of 2 last lines of the code:
grid(nx=NULL,ny=NULL,col = "lightgray", lty = "dotted",lwd = par("lwd"))
axis(1, las = 2)

I have now:

axis(1, labels =format(as.Date(my.data$date, origin="1970-01-01"),
"%Y-%m-%d"), at=my.data$date, las=2,cex.axis=0.7)
grid(nx=(length(my.data$date)-1),ny=NULL,col = "lightgray", lty =
"dotted",lwd = par("lwd"))

Dimitri

On Mon, Oct 4, 2010 at 3:56 PM, David Winsemius <dwinsemius at comcast.net> wrote:
>
> On Oct 4, 2010, at 3:28 PM, Dimitri Liakhovitski wrote:
>
>> Hello, everybody!
>> I have a code below that creates a data set and then a stacked bar
>> chart based on that data set.
>> No need to look at it - just notice please that my horizontal axis is
>> a date varible (x=my.data$date).
>> I have a question about the last 2 lines of this code:
>> grid(nx=NULL,ny=NULL,col = "lightgray", lty = "dotted",lwd = par("lwd"))
>> axis(1, las = 2)
>
> But you only gave two arguments to axis... the "side" and "las"???
>>
>> Could anyone tell me - what are the tick mark labels on my X axis? Why
>> are they not dates?
>
> Because they are the number of days since the "origin". Read the help page
> for Dates. If you want the text value for axis to be formatted, then consult
> the axis help page for the argument names and use the appropriate call to
> format:
>
> ?Dates
> ?axis  #   perhaps ... labels =format(my.data$date, "%Y-%m-%d")
>
> # but you will also need to decide where you want the tick marks
>
> Perhaps:
>
>> axis(1, labels =format(as.Date(axTicks(1), origin="1970-01-01"),
>> "%Y-%m-%d"), at=axTicks(1), col="red")
>
>
>
> ?format
>
>
>> axTicks(side=1)
>>
>> Is there any way to change them to actual dates as in my.data$date?
>> And also - is there a way to force the graph to display all tickmarks
>> on X axis - and not just 4 of them?
>>
>> Thank you!
>> Dimitri
>>
>>
>> my.data<-data.frame(date=c(20080301,20080401,20080501,20080601,20080701,20080801,20080901,20081001,20081101,20081201,20090101,20090201,20090301,20090401,20090501,20090601,20090701,20090801,20090901,20091001,20091101,20091201,20100101,20100201,20100301,20100402,20100503),
>> x=c(1.1, 1, 1.6, 1, 2, 1.5, 2.1, 1.3, 1.9, 1.1, 1, 1.6, 1, 2, 1.5,
>> 2.1, 1.3, 1.9, 1.1, 1, 1.6, 1, 2, 1.5, 2.1, 1.3, 1.9),
>>
>> y=c(-4,-3,-6,-5,-7,-5.2,-6,-4,-4.9,-4,-3,-6,-5,-7,-5.2,-6,-4,-4.9,-4,-3,-6,-5,-7,-5.2,-6,-4,-4.9),
>>
>> z=c(-0.2,-0.3,-0.4,-0.1,-0.2,-0.05,-0.2,-0.15,-0.06,-0.2,-0.3,-0.4,-0.1,-0.2,-0.05,-0.2,-0.15,-0.06,-0.06,-0.2,-0.3,-0.4,-0.1,-0.2,-0.05,-0.2,-0.15),
>>
>> a=c(10,13,15,15,16,17,15,16,14,10,13,15,15,16,17,15,16,14,10,13,15,15,16,17,15,16,14))
>> my.data$date<-as.character(my.data$date)
>> my.data$date<-as.Date(my.data$date,"%Y%m%d")
>> (my.data)
>> str(my.data)
>>
>> positives<-which(colSums(my.data[2:ncol(my.data)])>0) # which vars
>> have positive column sums?
>> negatives<-which(colSums(my.data[2:ncol(my.data)])<0) # which vars
>> have negative column sums?
>>
>> y.max<-1.1*max(rowSums(my.data[names(positives)])) # the max on the y
>> axis of the chart
>> y.min<-1.1*min(rowSums(my.data[names(negatives)])) # the min on the y
>> axis of the chart
>> ylim <- c(y.min, y.max)
>> order.positives<-rev(rank(positives))
>> order.of.pos.vars<-names(order.positives)
>> order.negatives<-rev(rank(negatives))
>> order.of.neg.vars<-names(order.negatives)
>> order<-c(order.negatives,order.positives)
>> order.of.vars<-names(order)   # the order of variables on the chart -
>> from the bottom up
>> ### so, the bottom-most area should be for z, the second from the
>> bottom area- for y (above z)
>>
>> all.colors<-c('red','blue','green','orange','yellow','purple')
>> xx <- c(my.data$date, rev(my.data$date))
>> bottom.y.coordinates<-rowSums(my.data[names(negatives)])
>>
>> plot(x=my.data$date, y=bottom.y.coordinates, ylim=ylim, col='white',
>> type='l', xaxt='n',
>>        ylab='Title for Y', xlab='Date', main='Chart Title')
>>
>> for(var in order.of.neg.vars){
>>        top.line.coords<-bottom.y.coordinates-my.data[[var]]
>>        bottom.coords<-c(bottom.y.coordinates,rev(top.line.coords))
>>        polygon(xx,bottom.coords,col=all.colors[which(names(my.data) %in%
>> var)])
>>        bottom.y.coordinates<-top.line.coords
>> }
>>
>> for(var in order.of.pos.vars){
>>        top.line.coords<-bottom.y.coordinates+my.data[[var]]
>>        bottom.coords<-c(bottom.y.coordinates,rev(top.line.coords))
>>        polygon(xx,bottom.coords,col=all.colors[which(names(my.data) %in%
>> var)])
>>        bottom.y.coordinates<-top.line.coords
>> }
>>
>> grid(nx=NULL,ny=NULL,col = "lightgray", lty = "dotted",lwd = par("lwd"))
>> axis(1, las = 2)
>>
>>
>> --
>> Dimitri Liakhovitski
>> Ninah Consulting
>> www.ninah.com
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>
> David Winsemius, MD
> West Hartford, CT
>
>



-- 
Dimitri Liakhovitski
Ninah Consulting
www.ninah.com