Re: [R] zigzag confidence interval in a plot

2013-05-17 Thread Peter Ehlers 

On 2013-05-17 06:03, Ozgul Inceoglu wrote:

Dear All,

When I plot the values and linear regression line for one data set, it is fine. 
But for another one I see zigzags, when I plot the confidence interval


cd

Depth   CHAOsep12RNA
9,94804
25,06   1476,83
40,04   1540,561404
50,11   1575,17
52,46   349,22
54,92   1941,5
57,29   1053,507042
60,11   1535,1
70,04   2244,963303
79,97   1954,507042
100,31  2679,140625



plot(cd$CHAOsep12RNA,cd$Depth, ylim = rev(range(0:100)), xlab=CHAO, ylab=Depth, 
pch=15, las=2, main=Sep12-RNA, cex.main=1)
lmR - lm(cd$Depth~cd$CHAOsep12RNA)
abline(lmR)

pconfR - predict(lmR,interval=confidence)
matlines(cd$CHAOsep12RNA,pconfR[,c(lwr,upr)], col=1, lty=2)

I also tried


newx - seq(min(cd$CHAOsep12RNA), max(cd$CHAOsep12RNA), length.out=11)
a - predict(lmR, newdata=data.frame(CHAO=newx), interval=c(confidence))
plot(cd$CHAOsep12RNA,cd$Depth, ylim = rev(range(0:100)), xlab=CHAO, ylab=Depth, 
pch=15, las=2, main=Sep12-RNA, cex.main=1)
abline(lmR)
lines(cd$CHAOsep12RNA, a[,2], lty=2)


But I see both cases kind of zigzags. What can it be the reason? thank you!



Sort your dataframe by x-values (CHAOsep12RNA).

Peter Ehlers

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Re: [R] zigzag confidence interval in a plot

2013-05-17 Thread Rui Barradas 

Hello,

Try the following.


lmR - lm(cd$Depth ~ cd$CHAOsep12RNA)
pconfR - predict(lmR,interval=confidence)
pcR - pconfR[order(pconfR[, 1]), ]  # Add this line

plot(cd$CHAOsep12RNA,cd$Depth, ylim = rev(range(0:100)), xlab=CHAO, 
ylab=Depth, pch=15, las=2, main=Sep12-RNA, cex.main=1)

abline(lmR)
matlines(sort(cd$CHAOsep12RNA), pcR[,c(lwr, upr)], col=1, lty=2) # 
changed



Hope this helps,

Rui Barradas

Em 17-05-2013 14:03, Ozgul Inceoglu escreveu:

Dear All,

When I plot the values and linear regression line for one data set, it is fine. 
But for another one I see zigzags, when I plot the confidence interval


cd

Depth   CHAOsep12RNA
9,94804
25,06   1476,83
40,04   1540,561404
50,11   1575,17
52,46   349,22
54,92   1941,5
57,29   1053,507042
60,11   1535,1
70,04   2244,963303
79,97   1954,507042
100,31  2679,140625



plot(cd$CHAOsep12RNA,cd$Depth, ylim = rev(range(0:100)), xlab=CHAO, ylab=Depth, 
pch=15, las=2, main=Sep12-RNA, cex.main=1)
lmR - lm(cd$Depth~cd$CHAOsep12RNA)
abline(lmR)

pconfR - predict(lmR,interval=confidence)
matlines(cd$CHAOsep12RNA,pconfR[,c(lwr,upr)], col=1, lty=2)

I also tried


newx - seq(min(cd$CHAOsep12RNA), max(cd$CHAOsep12RNA), length.out=11)
a - predict(lmR, newdata=data.frame(CHAO=newx), interval=c(confidence))
plot(cd$CHAOsep12RNA,cd$Depth, ylim = rev(range(0:100)), xlab=CHAO, ylab=Depth, 
pch=15, las=2, main=Sep12-RNA, cex.main=1)
abline(lmR)
lines(cd$CHAOsep12RNA, a[,2], lty=2)


But I see both cases kind of zigzags. What can it be the reason? thank you!



__
R-help@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.



__
R-help@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.