R help - Jan 2010 - Barchart bar lengths not proportionate

When I use barchart (with default formatting options), I get bars whose
lengths/heights are not proportional to their value. For example:

http://drop.io/wbagm6s/asset/capture-png

Many of the values in this chart are 1; however, because the blue bars
extend to the left of the "0" tick mark, those bars appear to
represent
higher numeric values. Is there a way to make the length of the bar
proportional to the data value, so that people looking at my chart are not
misled?

Thanks,

Rex

	[[alternative HTML version deleted]]

Rex,

I think this problem can be solved using xlim()/ylim() argument. Look at the
follwing code:

require(lattice)
da <- expand.grid(A=c("a","b"), x=1:4)
da$y <- c(1,5,6,3,2,0,6,0)

barchart(y~x|A, data=da, horizontal=FALSE)

barchart(y~x|A, data=da, horizontal=FALSE,
         ylim=c(0, 1.05*max(da$y)))

At your disposal.
Walmes.



Rex C. Eastbourne wrote:
> 
> When I use barchart (with default formatting options), I get bars whose
> lengths/heights are not proportional to their value. For example:
> 
> http://drop.io/wbagm6s/asset/capture-png
> 
> Many of the values in this chart are 1; however, because the blue bars
> extend to the left of the "0" tick mark, those bars appear to
represent
> higher numeric values. Is there a way to make the length of the bar
> proportional to the data value, so that people looking at my chart are not
> misled?
> 
> Thanks,
> 
> Rex
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.
> 
> 

-----
..oooO
..................................................................................................
..(....)... 0ooo...                              Walmes Zeviani
...\..(.....(.....)...     Master in Statistics and Agricultural
Experimentation
....\_)..... )../....       walmeszeviani at hotmail.com, Lavras - MG, Brasil
............
(_/............................................................................................
-- 
View this message in context:
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Sent from the R help mailing list archive at Nabble.com.

On Thu, Jan 14, 2010 at 1:16 AM, Rex C. Eastbourne
<rex.eastbourne at gmail.com> wrote:
> When I use barchart (with default formatting options), I get bars whose
> lengths/heights are not proportional to their value. For example:
>
> http://drop.io/wbagm6s/asset/capture-png
>
> Many of the values in this chart are 1; however, because the blue bars
> extend to the left of the "0" tick mark, those bars appear to
represent
> higher numeric values. Is there a way to make the length of the bar
> proportional to the data value, so that people looking at my chart are not
> misled?
Add 'origin = 0' as an argument.

-Deepayan

I think you should rather look at the origin= parameter in barchart. See

?panel.barchart for a discussion of this exact problem:
"  origin: the origin for the bars.  For grouped displays with 'stack
          TRUE', this argument is ignored and the origin set to 0. 
          Otherwise, defaults to 'NULL', in which case bars start at
          the left (or bottom) end of a panel.  This choice is
somewhat
          unfortuntate, as it can be misleading, but is the default
for
          historical reasons.  For tabular (or similar) data, 'origin
          0' is usually more appropriate; if not, one should
reconsider
          the use of a bar chart in the first place (dot plots are
          often a good alternative). "

The result of setting origin is more sensible:
require(lattice)
da <- expand.grid(A=c("a","b"), x=1:4)
da$y <- c(1,5,6,3,2,0,6,0)

barchart(y~x|A, data=da, horizontal=FALSE)

barchart(y~x|A, data=da, horizontal=FALSE, origin=0)
>>> Walmes Zeviani <walmeszeviani at hotmail.com> 14/01/2010
14:49:01 >>>
Rex,

I think this problem can be solved using xlim()/ylim() argument. Look
at the
follwing code:

require(lattice)
da <- expand.grid(A=c("a","b"), x=1:4)
da$y <- c(1,5,6,3,2,0,6,0)

barchart(y~x|A, data=da, horizontal=FALSE)

barchart(y~x|A, data=da, horizontal=FALSE,
         ylim=c(0, 1.05*max(da$y)))

At your disposal.
Walmes.



Rex C. Eastbourne wrote:
> 
> When I use barchart (with default formatting options), I get bars
whose
> lengths/heights are not proportional to their value. For example:
> 
> http://drop.io/wbagm6s/asset/capture-png 
> 
> Many of the values in this chart are 1; however, because the blue
bars
> extend to the left of the "0" tick mark, those bars appear to
represent
> higher numeric values. Is there a way to make the length of the bar
> proportional to the data value, so that people looking at my chart
are not
> misled?
> 
> Thanks,
> 
> Rex
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.
> 
> 

-----
..oooO
..................................................................................................
..(....)... 0ooo...                              Walmes Zeviani
...\..(.....(.....)...     Master in Statistics and Agricultural
Experimentation
....\_)..... )../....       walmeszeviani at hotmail.com, Lavras - MG,
Brasil
............
(_/............................................................................................
-- 
View this message in context:
http://n4.nabble.com/Barchart-bar-lengths-not-proportionate-tp1013702p1013918.html

Sent from the R help mailing list archive at Nabble.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.

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