This is almost it. Maybe it is as good as can be expected. The only problem
that I see is that this seems to form a Category/SubCategory pair where none
existed in the original data. For example, A might have two sub-categories a
and b, and B might have two categories c and d. As far as I can tell the method
that you outlined forms a Category/SubCategory pair like B a or B b where none
existed. This results in alot of empty lists and it seems to take a long time
to generate. But if that is as good as it gets then I can live with it.
I know that I said one more question. But I have run into a problem. c <-
split(x, x$Category) returns a vector of the rows in each of the categories.
Now I would like to access the "Quantity" column within this split vector. I
can see it listed. I just can't access it. I have tried c[1]$Quantity and
c[1,2] both which give me errors. Any ideas?
Sorry this is so hard for me. I am more used to C type arrays and C type arrays
of structures. This seems to be somewhat different.
Thank you.
Kevin
---- jim holtman <[EMAIL PROTECTED]> wrote:
> Is this something like what you were asking for? The output of a
> 'split' will be a list of the dataframe subsets for the categories you
> have specified.
>
> > x <- data.frame(g1=sample(LETTERS[1:2],30,TRUE),
> + g2=sample(letters[1:2], 30, TRUE),
> + g3=1:30)
> > y <- split(x, list(x$g1, x$g2))
> > str(y)
> List of 4
> $ A.a:'data.frame': 7 obs. of 3 variables:
> ..$ g1: Factor w/ 2 levels "A","B": 1 1 1 1 1 1 1
> ..$ g2: Factor w/ 2 levels "a","b": 1 1 1 1 1 1 1
> ..$ g3: int [1:7] 3 4 6 8 9 13 24
> $ B.a:'data.frame': 7 obs. of 3 variables:
> ..$ g1: Factor w/ 2 levels "A","B": 2 2 2 2 2 2 2
> ..$ g2: Factor w/ 2 levels "a","b": 1 1 1 1 1 1 1
> ..$ g3: int [1:7] 10 11 16 17 18 20 25
> $ A.b:'data.frame': 6 obs. of 3 variables:
> ..$ g1: Factor w/ 2 levels "A","B": 1 1 1 1 1 1
> ..$ g2: Factor w/ 2 levels "a","b": 2 2 2 2 2 2
> ..$ g3: int [1:6] 2 12 23 26 27 29
> $ B.b:'data.frame': 10 obs. of 3 variables:
> ..$ g1: Factor w/ 2 levels "A","B": 2 2 2 2 2 2 2 2 2 2
> ..$ g2: Factor w/ 2 levels "a","b": 2 2 2 2 2 2 2 2 2 2
> ..$ g3: int [1:10] 1 5 7 14 15 19 21 22 28 30
> > y
> $A.a
> g1 g2 g3
> 3 A a 3
> 4 A a 4
> 6 A a 6
> 8 A a 8
> 9 A a 9
> 13 A a 13
> 24 A a 24
>
> $B.a
> g1 g2 g3
> 10 B a 10
> 11 B a 11
> 16 B a 16
> 17 B a 17
> 18 B a 18
> 20 B a 20
> 25 B a 25
>
> $A.b
> g1 g2 g3
> 2 A b 2
> 12 A b 12
> 23 A b 23
> 26 A b 26
> 27 A b 27
> 29 A b 29
>
> $B.b
> g1 g2 g3
> 1 B b 1
> 5 B b 5
> 7 B b 7
> 14 B b 14
> 15 B b 15
> 19 B b 19
> 21 B b 21
> 22 B b 22
> 28 B b 28
> 30 B b 30
>
> > y[[2]]
> g1 g2 g3
> 10 B a 10
> 11 B a 11
> 16 B a 16
> 17 B a 17
> 18 B a 18
> 20 B a 20
> 25 B a 25
> >
> >
> >
>
>
> On Sat, Jul 12, 2008 at 8:51 PM, <[EMAIL PROTECTED]> wrote:
> > OK. Now I know that I am dealing with a data frame. One last question on
> > this topic. a <- read.csv() gives me a dataframe. If I have 'c <- split(x,
> > x$Category), then what is returned by split in this case? c[1] seems to be
> > OK but c[2] is not right in my mind. If I run ci <- split(nrow(a),
> > a$Category). And then ci[1] seems to be the rows associated with the first
> > category, c[2] is the indices/rows associated with the second category,
> > etc. But this seems different than c[1], c[2], etc.
> >
> > Using the techniques below I can get the information on the categories. Now
> > as an extra level of complexity there are SubCategories within each
> > Category. Assume that the SubCategory names are not unique within the
> > dataset so if I want the SubCategory data I need to retrive the indices (or
> > data) for the Category and SubCategory pair. In other words if I have a
> > Category that ranges from 'A' to 'Z', it is possible that I might have a
> > subcategory A a, A b (where a and b are the sub category names). I also
> > might have B a, B b. I want all of the sub categories A a. NOT the
> > subcategories a (because that might include B a which would be different).
> > I am guessing that this will take more than a simple 'split'.
> >
> > Thank you.
> >
> > Kevin
> >
> > ---- Duncan Murdoch <[EMAIL PROTECTED]> wrote:
> >> On 12/07/2008 3:59 PM, [EMAIL PROTECTED] wrote:
> >> > I am sorry but if read.csv returns a dataframe and a dataframe is like a
> >> > matrix and I have a set of input like below and a[1,] gives me the first
> >> > row, what is the second index? From what I read and your input I am
> >> > guessing that it is the column number. So a[1,1] would return the
> >> > DayOfYear column for the first row, right? What does a$DayOfYear return?
> >>
> >> a$DayOfYear would be the same as a[,1] or a[,"DayOfYear"], i.e. it would
> >> return the entire first column.
> >>
> >> Duncan Murdoch
> >>
> >> >
> >> > Thank you for your patience.
> >> >
> >> > Kevin
> >> >
> >> > ---- Duncan Murdoch <[EMAIL PROTECTED]> wrote:
> >> >> On 12/07/2008 12:31 PM, [EMAIL PROTECTED] wrote:
> >> >>> I am using a simple R statement to read in the file:
> >> >>>
> >> >>> a <- read.csv("Sample.dat", header=TRUE)
> >> >>>
> >> >>> There is alot of data but the first few lines look like:
> >> >>>
> >> >>> DayOfYear,Quantity,Fraction,Category,SubCategory
> >> >>> 1,82,0.0000390392720794458,(Unknown),(Unknown)
> >> >>> 2,78,0.0000371349173438631,(Unknown),(Unknown)
> >> >>> . . .
> >> >>> 71,2,0.0000009521773677913,WOMEN,Piratesses
> >> >>> 72,4,0.0000019043547355827,WOMEN,Piratesses
> >> >>> 73,3,0.0000014282660516870,WOMEN,Piratesses
> >> >>> 74,14,0.0000066652415745395,WOMEN,Piratesses
> >> >>> 75,2,0.0000009521773677913,WOMEN,Piratesses
> >> >>>
> >> >>> If I read the data in as above, the command
> >> >>>
> >> >>> a[1]
> >> >>>
> >> >>> results in the output
> >> >>>
> >> >>> [ reached getOption("max.print") -- omitted 16193 rows ]]
> >> >>>
> >> >>> Shouldn't this be the first row?
> >> >> No, the first row would be a[1,]. read.csv() returns a dataframe, and
> >> >> those are indexed with two indices to treat them like a matrix, or with
> >> >> one index to treat them like a list of their columns.
> >> >>
> >> >> Duncan Murdoch
> >> >>
> >> >>> a$Category[1]
> >> >>>
> >> >>> results in the output
> >> >>>
> >> >>> [1] (Unknown)
> >> >>> 4464 Levels: Tags ... WOMEN
> >> >>>
> >> >>> But
> >> >>>
> >> >>> a$Category[365]
> >> >>>
> >> >>> gives me:
> >> >>>
> >> >>> [1] 7 Plates (Dessert),Western\n120,5,0.0000023804434194784,7 Plates
> >> >>> (Dessert)
> >> >>> 4464 Levels: Tags ... WOMEN
> >> >>>
> >> >>> There is something fundamental about either vectors of the read.csv
> >> >>> command that I am missing here.
> >> >>>
> >> >>> Thank you.
> >> >>>
> >> >>> Kevin
> >> >>>
> >> >>> ---- jim holtman <[EMAIL PROTECTED]> wrote:
> >> >>>> Please provide commented, minimal, self-contained, reproducible code,
> >> >>>> or at least a before/after of what you data would look like. Taking a
> >> >>>> guess at what you are asking, here is one way of doing it:
> >> >>>>
> >> >>>>
> >> >>>>> x <- data.frame(cat=sample(LETTERS[1:3],20,TRUE),a=1:20, b=runif(20))
> >> >>>>> x
> >> >>>> cat a b
> >> >>>> 1 B 1 0.65472393
> >> >>>> 2 C 2 0.35319727
> >> >>>> 3 B 3 0.27026015
> >> >>>> 4 A 4 0.99268406
> >> >>>> 5 C 5 0.63349326
> >> >>>> 6 A 6 0.21320814
> >> >>>> 7 C 7 0.12937235
> >> >>>> 8 A 8 0.47811803
> >> >>>> 9 A 9 0.92407447
> >> >>>> 10 A 10 0.59876097
> >> >>>> 11 A 11 0.97617069
> >> >>>> 12 A 12 0.73179251
> >> >>>> 13 B 13 0.35672691
> >> >>>> 14 C 14 0.43147369
> >> >>>> 15 C 15 0.14821156
> >> >>>> 16 C 16 0.01307758
> >> >>>> 17 B 17 0.71556607
> >> >>>> 18 B 18 0.10318424
> >> >>>> 19 C 19 0.44628435
> >> >>>> 20 B 20 0.64010105
> >> >>>>> # create a list of the indices of the data grouped by 'cat'
> >> >>>>> split(seq(nrow(x)), x$cat)
> >> >>>> $A
> >> >>>> [1] 4 6 8 9 10 11 12
> >> >>>>
> >> >>>> $B
> >> >>>> [1] 1 3 13 17 18 20
> >> >>>>
> >> >>>> $C
> >> >>>> [1] 2 5 7 14 15 16 19
> >> >>>>
> >> >>>>> # or do you want the data
> >> >>>>> split(x, x$cat)
> >> >>>> $A
> >> >>>> cat a b
> >> >>>> 4 A 4 0.9926841
> >> >>>> 6 A 6 0.2132081
> >> >>>> 8 A 8 0.4781180
> >> >>>> 9 A 9 0.9240745
> >> >>>> 10 A 10 0.5987610
> >> >>>> 11 A 11 0.9761707
> >> >>>> 12 A 12 0.7317925
> >> >>>>
> >> >>>> $B
> >> >>>> cat a b
> >> >>>> 1 B 1 0.6547239
> >> >>>> 3 B 3 0.2702601
> >> >>>> 13 B 13 0.3567269
> >> >>>> 17 B 17 0.7155661
> >> >>>> 18 B 18 0.1031842
> >> >>>> 20 B 20 0.6401010
> >> >>>>
> >> >>>> $C
> >> >>>> cat a b
> >> >>>> 2 C 2 0.35319727
> >> >>>> 5 C 5 0.63349326
> >> >>>> 7 C 7 0.12937235
> >> >>>> 14 C 14 0.43147369
> >> >>>> 15 C 15 0.14821156
> >> >>>> 16 C 16 0.01307758
> >> >>>> 19 C 19 0.44628435
> >> >>>>
> >> >>>>
> >> >>>> On Sat, Jul 12, 2008 at 3:32 AM, <[EMAIL PROTECTED]> wrote:
> >> >>>>> I have search the archive and I could not find what I need so I will
> >> >>>>> try to ask the question here.
> >> >>>>>
> >> >>>>> I read a table in (read.table)
> >> >>>>>
> >> >>>>> a <- read.table(.....)
> >> >>>>>
> >> >>>>> The table has column names like DayOfYear, Quantity, and Category.
> >> >>>>>
> >> >>>>> The values in the row for Category are strings (characters).
> >> >>>>>
> >> >>>>> I want to get all of the rows grouped by Category. The number of
> >> >>>>> unique category names could be around 50. Say for argument sake the
> >> >>>>> number of categories is exactly 50. Can I somehow get a vector of
> >> >>>>> length 50 containing the rows corresponding to the category (another
> >> >>>>> vector)? I realize I can access any row a[i]$Category (right?). But
> >> >>>>> I wanta vector containing the rows corresponding to each distinct
> >> >>>>> Category name.
> >> >>>>>
> >> >>>>> Thank you.
> >> >>>>>
> >> >>>>> Kevin
> >> >>>>>
> >> >>>>> ______________________________________________
> >> >>>>> [email protected] 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.
> >> >>>>>
> >> >>>>
> >> >>>> --
> >> >>>> Jim Holtman
> >> >>>> Cincinnati, OH
> >> >>>> +1 513 646 9390
> >> >>>>
> >> >>>> What is the problem you are trying to solve?
> >> >>> ______________________________________________
> >> >>> [email protected] 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.
> >>
> >
> >
>
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem you are trying to solve?
______________________________________________
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and provide commented, minimal, self-contained, reproducible code.
