[R] Bar charts, frequencies known, intervals of varying width

scriptham2 stewart.porteous at permarock.com
Wed Nov 23 16:50:15 CET 2011


I would like to plot bar charts in a particular way. The intervals are not
evenly distributed and are in a data frame column called size and the
relative frequencies are in a second column called mass. Both size and mass
are continuous ratio data to all intents and purposes. The data actually
represents sieving of sand where $size is sieve aperture and where $mass is
the amount remaining on the sieve. 

So if I sieve 100g of sand through increasingly fine sieves nothing remains
on the coarsest sieve say 2500 microns. Between 2000 and 2500 microns there
is 0.2g remining on the 2000micron sieve etc. as per the data supplied.

size, mass
2500, 0
2000, 0.2
1700, 1.8
1400, 5
1000, 13
800, 40
600, 20
300, 15
180, 3
<180, 2

The data here I have made up for simplicity. In general sands tend to be
distributed as lognormal curves and mixtures of sands are combined as the
mixture of 2 or more lognormal distributions.

I would like to fit 2, 3 or preferably 4 parameter log normal distributions
and plot these cumulative distributions on the charts. 

The problems are: I can't seem to find how to do the bar charts in R and 
I have not found in the past how to fit 3 or 4 parameter log normal
cumulative distributions in R

Please help.

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