On Feb 11, 2010, at 7:32 PM, Keeeeeeee wrote:
Dear helpers,
FYI, I am a beginner of R, just have dealt with MATLAB or JAVA.
I want to know how to solve one problem given 4 variables: year_1,
year_2,
tall_1, tall_2.
The tall_1 is measured at year_1 and tall_2 at year_2.
The tall has grown up such as uniformly 1 cm/yr.
The data is like
year_1 year_2 tall_1 tall_2
2007 2010 12 15
1999 2009 6 16
2003 2005 11 13
2002 2009 3 10
. . . . .
. . . . .
. . . . .
. . . . .
So I need to get the average tall of the plant against year, for all
the
years of available data.
For an individual plant, Wouldn't this just be (tall_2 + tall_1)/2?
(Or if you wanted to do it the hard way then use seq and divide by
number of years:)
> dfp <- rd.txt("year_1 year_2 tall_1 tall_2
+ 2007 2010 12 15
+ 1999 2009 6 16
+ 2003 2005 11 13
+ 2002 2009 3 10")
> dfp$plant.avg <- apply(dfp, 1, function(x) sum(seq(x[3], x[4]) ) /
(x[2]-x[1]+1) )
> dfp
year_1 year_2 tall_1 tall_2 plant.avg
1 2007 2010 12 15 13.5
2 1999 2009 6 16 11.0
3 2003 2005 11 13 12.0
4 2002 2009 3 10 6.5
> dfp$plant.avg2 <- apply(dfp, 1, function(x) (x[3]+ x[4] ) / 2 )
> dfp
year_1 year_2 tall_1 tall_2 plant.avg plant.avg2
1 2007 2010 12 15 13.5 13.5
2 1999 2009 6 16 11.0 11.0
3 2003 2005 11 13 12.0 12.0
4 2002 2009 3 10 6.5 6.5
I don't think you need to create the display below if you want to
answer the question posed. And if this happens to be homework, be sure
that I get credit.
--
David
The year_1 and year_2 are recorded so that a plant is alive if the
year of a
question is equal to or grater than the year_1 and equal to and less
than
the year_2.
For example,
1999 2000 2001 2002 2003 2004 2005 2006
2007 2008
2009 2010
6 7 8 9 10 11 12
13 14 15 16
3 4
5 6
7 8 9 10
11 12 13
12 13 14 15
avg
6 7 8 6 25/3 ...etc.
Since the amount of the data is too huge, I need to use appropriate
functions and algorithm but I am
not good at programming R.
I wish you help me out from this hell problem please.
Thanks,
Keeeeeeee
--
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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