All -
Not sure if this is a real programming question, but here goes:
I have data that looks like
Lake Length Weight
1 158 45
1 179 70
1 200 125
1 202 150
1 206 145
1 209 165
1 210 140
1 215 175
1 216 152
1 220 150
1 221 165
...
where lake goes from 1 - 84 and the number of rows for each lake is variable
(but > ~20).
I'm trying to do two things: 1) build a simple linear model of the form
{lm(log10(Weight)~log10(Length)}
for every separate lake in the data set; 2) I'd like to save the intercepts
and slopes
from each of these linear regressions into a seperate data frame. Any ideas? I
think it would
probably require some kind of 'for' statement, but I'm just not that
smart.
Thanks for your help,
SR
Steven H. Ranney
Graduate Research Assistant (Ph.D)
USGS Montana Cooperative Fishery Research Unit
Montana State University
PO Box 173460
Bozeman, MT 59717-3460
phone: (406) 994-6643
fax: (406) 994-7479
[[alternative HTML version deleted]]
On 8/22/2008 5:34 PM, Ranney, Steven wrote:> All - > > Not sure if this is a real programming question, but here goes: > > I have data that looks like > > Lake Length Weight > 1 158 45 > 1 179 70 > 1 200 125 > 1 202 150 > 1 206 145 > 1 209 165 > 1 210 140 > 1 215 175 > 1 216 152 > 1 220 150 > 1 221 165 > ... > > where lake goes from 1 - 84 and the number of rows for each lake is variable (but > ~20). > I'm trying to do two things: 1) build a simple linear model of the form > > {lm(log10(Weight)~log10(Length)} > > for every separate lake in the data set; 2) I'd like to save the intercepts and slopes > from each of these linear regressions into a seperate data frame. Any ideas? I think it would > probably require some kind of 'for' statement, but I'm just not that smart.Assuming the data are in a data frame called "mydf": library(nlme) fm1 <- lmList(log10(Weight)~log10(Length) | Lake, mydf) coef(fm1) ?lmList or t(sapply(split(mydf, mydf$Lake), function(x){coef(lm(log10(Weight)~log10(Length), data=x))}))> Thanks for your help, > > SR > > Steven H. Ranney > Graduate Research Assistant (Ph.D) > USGS Montana Cooperative Fishery Research Unit > Montana State University > PO Box 173460 > Bozeman, MT 59717-3460 > > phone: (406) 994-6643 > fax: (406) 994-7479 > > > [[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. >-- Chuck Cleland, Ph.D. NDRI, Inc. (www.ndri.org) 71 West 23rd Street, 8th floor New York, NY 10010 tel: (212) 845-4495 (Tu, Th) tel: (732) 512-0171 (M, W, F) fax: (917) 438-0894
Dear Steven,
Take a look at the lmList function in the nlme package. It does what you
want to do.
HTH,
Thierry
------------------------------------------------------------------------
----
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature
and Forest
Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
methodology and quality assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium
tel. + 32 54/436 185
Thierry.Onkelinx op inbo.be
www.inbo.be
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than asking him to perform a post-mortem examination: he may be able to
say what the experiment died of.
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~ Roger Brinner
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ensure that a reasonable answer can be extracted from a given body of
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-----Oorspronkelijk bericht-----
Van: r-help-bounces op r-project.org [mailto:r-help-bounces op r-project.org]
Namens Ranney, Steven
Verzonden: vrijdag 22 augustus 2008 23:34
Aan: r-help op r-project.org
Onderwerp: [R] Newbie programming help
All -
Not sure if this is a real programming question, but here goes:
I have data that looks like
Lake Length Weight
1 158 45
1 179 70
1 200 125
1 202 150
1 206 145
1 209 165
1 210 140
1 215 175
1 216 152
1 220 150
1 221 165
...
where lake goes from 1 - 84 and the number of rows for each lake is
variable (but > ~20).
I'm trying to do two things: 1) build a simple linear model of the form
{lm(log10(Weight)~log10(Length)}
for every separate lake in the data set; 2) I'd like to save the
intercepts and slopes
from each of these linear regressions into a seperate data frame. Any
ideas? I think it would
probably require some kind of 'for' statement, but I'm just not that
smart.
Thanks for your help,
SR
Steven H. Ranney
Graduate Research Assistant (Ph.D)
USGS Montana Cooperative Fishery Research Unit
Montana State University
PO Box 173460
Bozeman, MT 59717-3460
phone: (406) 994-6643
fax: (406) 994-7479
[[alternative HTML version deleted]]
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