[R] Help with lattice, regressions and respective lines

[Jose Claudio Faria]

# Dear R list,
#
# I'm needing help with lattice, regression and respective lines.
# My data is below:

bra  = gl(2, 24, label = c('c', 's'))
em   = rep(gl(3, 8,  label = c('po', 'pov', 'ce')), 2)
tem  = rep(c(0, 0, 30, 30, 60, 60, 90, 90), 6)
tem2 = tem^2
r    = rep(1:2, 24)
y    = c(40.58, 44.85, 32.55, 35.68, 64.86, 51.95, 42.52, 52.21,
          40.58, 44.85, 33.46, 46.09, 12.75, 18.01, 16.82, 13.69,
          40.58, 44.85, 34.45, 29.89, 34.91, 28.10, 27.52, 22.24,
          48.68, 47.25, 45.58, 45.33, 41.03, 51.20, 45.85, 54.45,
          48.68, 47.25, 19.88, 19.67, 16.20, 13.49, 13.75, 18.80,
          48.68, 47.25, 42.19, 39.91, 34.69, 34.11, 32.74, 34.24)

Df = data.frame(bra, em, tem, tem2, r, y)

# Regressions
attach(Df)
   Dfs1=subset(Df, (bra=='s' & em=='pov'), select=c(bra, em, tem, tem2, r, y))
   Dfs1
   rlin1=lm(y ~ tem + tem2, data=Dfs1)
   summary(rlin1)

   Dfs2=subset(Df, (bra=='s' & em=='po'), select=c(bra, em, tem, r, y))
   Dfs2
   rlin2=lm(y ~ tem, data=Dfs2)
   summary(rlin2)

   Dfs3=subset(Df, (bra=='s' & em=='ce'), select=c(bra, em, tem, tem2, r, y))
   Dfs3
   rlin3=lm(y ~ tem + tem2, data=Dfs3)
   summary(rlin3)
detach(Df)

# I would like to plot with lattice 'y ~ tem | em',
# with the panels ('po', 'pov' and 'ce'),
# and the its respective regressions lines:
# a) linear for panel 'po' or better, without line;
# b) quadratic for 'pov' and 'ce'

# Is it possible? Could somebody hel me?

# I'm trying:
library(lattice)
attach(Df)
   Dfs=subset(Df, bra=='s', select=c(bra, em, tem, y))
   Dfs
   xyplot(y ~ tem | em,
          data = Dfs, ylim=c(10, 60), xlim=c(-10, 110),
          ylab='y', xlab='Time, days',
          layout = c(3,1))
detach(Df)

TIA,
-- 
Jose Claudio Faria
Brasil/Bahia/UESC/DCET
Estatistica Experimental/Prof. Adjunto
mails:
  joseclaudio.faria at terra.com.br
  jc_faria at uesc.br
  jc_faria at uol.com.br
tel: 73-3634.2779