Have a look at the reshape package.
Assuming that your data is in a data.frame called "dataset".
cast(Date ~ ., data = dataset, value = "count", fun = sum)
cast(Date ~ class, data = dataset, value = "count", fun = sum)
cast(Date + class ~ ., data = dataset, value = "count", fun = sum)
Or the plyr package
ddply(dataset, c("Date"), function(x){c(Sum_of_counts =
sum(x$count))})
ddply(dataset, c("Date", "class"),
function(x){c(Sum_of_counts sum(x$count))})
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 at inbo.be
www.inbo.be
To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to
say what the experiment died of.
~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data.
~ Roger Brinner
The combination of some data and an aching desire for an answer does not
ensure that a reasonable answer can be extracted from a given body of
data.
~ John Tukey
-----Oorspronkelijk bericht-----
Van: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
Namens Shaun Grannis
Verzonden: woensdag 26 augustus 2009 15:07
Aan: r-help at r-project.org
Onderwerp: [R] counting subgroup sums within a data frame
Hi,
I'm sure there's an easy approach to this issue, I'm just not seeing
it.
I have a data frame of the following form:
Date class subclass count
8/1/2009 A X 1
8/1/2009 B X 2
8/1/2009 A Y 9
8/1/2009 B Y 3
8/2/2009 A X 1
8/2/2009 B X 5
8/2/2009 A Y 4
8/2/2009 B Y 2
8/3/2009 A X 6
8/3/2009 B X 4
8/3/2009 A Y 3
8/3/2009 B Y 4
8/4/2009 A X 1
8/4/2009 B X 9
8/4/2009 A Y 3
8/4/2009 B Y 5
8/5/2009 A X 3
8/5/2009 B X 7
8/5/2009 A Y 2
8/5/2009 B Y 1
I would like to create a data frame of the sum the daily counts for,
say, class 'A', like so:
Date sum_of_counts
8/1/2009 10
8/2/2009 5
8/3/2009 9
8/4/2009 4
8/5/2009 5
I ultimately would like to do sum of counts on all classes and
subclasses. It seems that this is equivalent to a GROUP BY query in
SQL.
I'm sure this is possible in R. Any suggestions?
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