Hi
> [R] How do I make proper use of the by() function?
>
> Dear list,
>
> I have a function that uses values from two vectors and spits out one
new
> vector based on all the values of the two original vectors, and with
the
> same length as them.
> Ok, I would now like to be able to apply that function simply on two
columns
> in a data frame, divided by the levels of factors in the data frame.
>
> I'm trying to use by() for this, but the output is too hard to use. What
I
> am doing is this:
>
> by(df, list(df$Factor1,df$Factor2),function(x)
> my_function(x$col1,x$col2),simplify=TRUE)
by(df, list(df$Factor1,df$Factor2),function(x)
my_function(x$col1,x$col2),simplify=TRUE)
Error in df$Factor1 : object of type 'closure' is not subsettable
I get this kind of error which is because I do not have any df object
other than df function from stats package.
If I understand correctly you want maybe either aggregate or ave
> milan
pc lot bettong bet sira vyber betctc
1 1 56 89.95 109.25 3.000 b 88.37
2 2 66 86.87 100.96 3.156 a NA
3 3 84 93.91 101.21 3.120 a NA
4 4 89 89.48 100.00 3.010 a NA
5 5 41 110.15 116.92 3.597 b 106.37
6 6 44 96.53 106.54 3.057 b NA
7 7 47 94.94 104.91 2.857 b NA
8 8 62 90.30 111.05 3.210 b NA
9 9 64 96.41 102.56 3.180 a 90.79
10 10 65 95.04 101.15 3.200 a NA
11 11 57 88.27 104.71 3.060 b NA
12 13 74 91.98 104.93 3.470 a NA
> aggregate(milan[,2:5], list(milan$vyber), sum)
Group.1 lot bettong bet sira
1 a 442 553.69 610.81 19.136
2 b 307 570.14 653.38 18.781
> sapply(milan[,2:5], function(x) ave(x, milan$vyber, "sum"))
lot bettong bet sira
[1,] 51.16667 95.02333 108.8967 3.130167
[2,] 73.66667 92.28167 101.8017 3.189333
[3,] 73.66667 92.28167 101.8017 3.189333
[4,] 73.66667 92.28167 101.8017 3.189333
[5,] 51.16667 95.02333 108.8967 3.130167
[6,] 51.16667 95.02333 108.8967 3.130167
[7,] 51.16667 95.02333 108.8967 3.130167
[8,] 51.16667 95.02333 108.8967 3.130167
[9,] 73.66667 92.28167 101.8017 3.189333
[10,] 73.66667 92.28167 101.8017 3.189333
[11,] 51.16667 95.02333 108.8967 3.130167
[12,] 73.66667 92.28167 101.8017 3.189333
But maybe I am wrong, I still only try to learn mind reading.
>
> and the output is too complex to be used in a simple way. Actually, I
just
> want something like a data frame, where the results vectors are placed
in
> one column and the conditions under which they were produced (i.e. the
> values of the factors according to which the data set were divided) in
other
> columns.
>
> This does not seem to be provided by by(), and aggregate only provides
me
> with the ability to use values from one column, right?
> So, are there other functions I could use?
>
> Thanks!
>
> /Fredrik
>
> --
> "Life is like a trumpet - if you don't put anything into it, you don't
get
> anything out of it."
>
> [[alternative HTML version deleted]]
>
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