[R] Question on R lattice graphics

[Julie Hope]

Hi,

I am currently using the lattice library and trellis graphs to explore my
data.  Without going into too much detail of the data I just have a
question about how dot plot in the lattice library scales things...

I have normalised data that I am exploring as a function of time
partitioned by Date

*dotplot(NormCarbs ~ time | date)*

I also wanted to look at this Normalised data as a function of a conc,
again partitioned by Date

*dotplot(NormCarbs ~ ugml1 | date)*

For the first plot above - the Normcarbs on Y axis is the scale of my
original data (0 - 0.1) - (I have very low values)

However when the second plot above is run in R, my scale jumps to 1-100 on
the Y axis for NormCarbs?

I have no idea if the fact that the ugml1 on the X axis is in the region 0
- 350 ugml1 has anything to do with this?  Is R correcting to keep both
variables in the same order of magnitude?

The NormCarbs data for each plot are both draw from the same column of data
in my csv file  in which the values are between 0 - 0.1.

The second plot looks great actually, I'm just wondering what R is doing.
The code above is all I have specified?

Is it scaling it to allow me to see the data better?  I can't really
decipher the first plots data as everything is so close together so it
would be good to be able to control this to allow me to explore the data
better before I start to

If so, is there a way for me to control this (i.e. by controlling the
scaling)

What is R doing mathematically to my data to get this?

*Any help on this would be very much appreciated.  *

*Thank you!*

*Julie*



Julie Hope (NERC PhD Student)
Sediment Ecology Research Group, University of St Andrews
& School of Geoscience, Bangor University
Scottish Oceans Institute
University of St Andrews, East Sands
St Andrews, Fife
KY16 8LB
Tel No:  01334 463469 / Email: jah23 at st-andrews.ac.uk
Web: http://synergy.st-andrews.ac.uk/serg

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