Re: [R] Is this sapply behaviour normal?
On Wed, Jun 25, 2008 at 6:00 PM, Victor Homar <[EMAIL PROTECTED]> wrote: > > Hi, I'm trying to use sapply to compute the min of several variables, > each > of them stored in data.frames, grouped as a list: > Is it normal that mean() and min() produce different objects dimensions? > it is exactly as documented in ?mean and ?min mean is a generic function which has a separate method for data frames: mean.data.frame <- mean.data.frame function (x, ...) sapply(x, mean, ...) min has no separate method for data frames (so you'll get just one number), but you can define one easily: min.data.frame <- function(...) sapply(..., min) k > str(dats) > List of 5 >$ log20:'data.frame': 83 obs. of 5 variables: > ..$ DATE : int [1:83] 2001081500 2001081512 2001081600 2001081612 > 2001081700 2001081712 2001081800 2001081812 2001081900 2001081912 ... > ..$ logrho: num [1:83] 1.16 -1.30 -1.30 -1.30 -1.30 ... > ..$ w2: num [1:83] 1.01 1.27 1.24 1.31 1.28 ... > ..$ rms : num [1:83] 5.001 0.630 0.616 0.685 0.655 ... > ..$ maxi : num [1:83] 8.66 3.39 3.83 3.35 3.23 ... >$ log30:'data.frame': 71 obs. of 5 variables: > ..$ DATE : int [1:71] 2001081500 2001081512 2001081600 2001081612 > 2001081700 2001081712 2001081800 2001081812 2001081900 2001081912 ... > ..$ logrho: num [1:71] 1.16 -1.00 -1.00 -1.00 -1.00 ... > ..$ w2: num [1:71] 1.01 1.27 1.21 1.29 1.27 ... > ..$ rms : num [1:71] 5.001 0.851 0.802 0.877 0.864 ... > ..$ maxi : num [1:71] 8.66 4.57 4.62 4.27 4.47 ... >$ log40:'data.frame': 14 obs. of 5 variables: > ..$ DATE : int [1:14] 2001081500 2001081512 2001081600 2001081612 > 2001081700 2001081712 2001081800 2001081812 2001081900 2001081912 ... > ..$ logrho: num [1:14] 1.16 -0.50 -0.50 -0.50 -0.50 ... > ..$ w2: num [1:14] 1.01 1.27 1.18 1.23 1.17 ... > ..$ rms : num [1:14] 5.00 1.40 1.26 1.36 1.25 ... > ..$ maxi : num [1:14] 8.66 7.54 6.39 6.68 5.83 ... >$ log50:'data.frame': 69 obs. of 5 variables: > ..$ DATE : int [1:69] 2001081500 2001081512 2001081600 2001081612 > 2001081700 2001081712 2001081800 2001081812 2001081900 2001081912 ... > ..$ logrho: num [1:69] 1.16 -1.50 -1.50 -1.50 -1.50 ... > ..$ w2: num [1:69] 1.01 1.27 1.25 1.33 1.31 ... > ..$ rms : num [1:69] 5.001 0.516 0.516 0.577 0.554 ... > ..$ maxi : num [1:69] 8.66 2.77 3.44 2.92 3.25 ... >$ log60:'data.frame': 66 obs. of 5 variables: > ..$ DATE : int [1:66] 2001081500 2001081512 2001081600 2001081612 > 2001081700 2001081712 2001081800 2001081812 2001081900 2001081912 ... > ..$ logrho: num [1:66] 1.16 -2.00 -2.00 -2.00 -2.00 ... > ..$ w2: num [1:66] 1.01 1.27 1.27 1.34 1.34 ... > ..$ rms : num [1:66] 5.001 0.313 0.326 0.371 0.366 ... > ..$ maxi : num [1:66] 8.66 1.68 2.43 2.23 3.85 ... > > sapply(dats,mean) > log20 log30 log40 log50 > log60 > DATE2.001088e+09 2.001087e+09 2.001082e+09 2.001087e+09 > 2.001086e+09 > logrho -1.270326e+00 -9.695748e-01 -3.816967e-01 -1.461383e+00 > -1.951941e+00 > w2 1.324907e+00 1.283293e+00 1.217808e+00 1.345297e+00 > 1.398435e+00 > rms 7.752963e-01 9.623266e-01 1.636949e+00 6.788993e-01 > 4.810029e-01 > maxi4.016900e+00 4.466865e+00 6.205573e+00 3.672405e+00 > 2.898055e+00 > > sapply(dats,min) >log20 log30 log40 log50 log60 > -1.3000708 -1.960 -0.5000176 -1.5001134 -2.0001350 > Thanks for your help, > Víctor. > -- > --- > Víctor Homar Santaner > Grup de Meteorologia > > Edif. Mateu Orfila Tel: +34 971 17 1376 > Universitat de les Illes BalearsFax: +34 971 17 3426 > 07122 Palma de Mallorca (SPAIN) Email: [EMAIL PROTECTED] > > Knowledge is contagious. Infect truth. > --- > > References > > 1. mailto:[EMAIL PROTECTED] > __ > R-help@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. > [[alternative HTML version deleted]] __ R-help@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.
Re: [R] Is this sapply behaviour normal?
The answer to your question is ``yeah, sort of''. The reason for the
difference is that mean() is generic and has a method for data frames,
according to which the mean of each column of the data frame is found
in some ``appropriate'' manner. (Essentially the columns of the data
frame must be either numeric or have some sort of date persuasion, else
you get a warning and an NA for the column in question. The function
min()
is not generic and so if you hit a data frame with min() it (apparently)
treats that data frame as if it were an atomic vector of data and finds
the minimum of that atomic vector. Given, of course, that doing so
makes
sense.
It would seem that you want min() to mimic the behaviour of mean(). To
achieve this you can, in this instance at least (I think!) simply do
sapply(dats,function(x){sapply(x,min)})
HTH.
cheers,
Rolf Turner
On 26/06/2008, at 3:00 AM, Victor Homar wrote:
Hi, I'm trying to use sapply to compute the min of several
variables, each
of them stored in data.frames, grouped as a list:
Is it normal that mean() and min() produce different objects
dimensions?
str(dats)
List of 5
$ log20:'data.frame': 83 obs. of 5 variables:
..$ DATE : int [1:83] 2001081500 2001081512 2001081600
2001081612
2001081700 2001081712 2001081800 2001081812 2001081900
2001081912 ...
..$ logrho: num [1:83] 1.16 -1.30 -1.30 -1.30 -1.30 ...
..$ w2: num [1:83] 1.01 1.27 1.24 1.31 1.28 ...
..$ rms : num [1:83] 5.001 0.630 0.616 0.685 0.655 ...
..$ maxi : num [1:83] 8.66 3.39 3.83 3.35 3.23 ...
$ log30:'data.frame': 71 obs. of 5 variables:
..$ DATE : int [1:71] 2001081500 2001081512 2001081600
2001081612
2001081700 2001081712 2001081800 2001081812 2001081900
2001081912 ...
..$ logrho: num [1:71] 1.16 -1.00 -1.00 -1.00 -1.00 ...
..$ w2: num [1:71] 1.01 1.27 1.21 1.29 1.27 ...
..$ rms : num [1:71] 5.001 0.851 0.802 0.877 0.864 ...
..$ maxi : num [1:71] 8.66 4.57 4.62 4.27 4.47 ...
$ log40:'data.frame': 14 obs. of 5 variables:
..$ DATE : int [1:14] 2001081500 2001081512 2001081600
2001081612
2001081700 2001081712 2001081800 2001081812 2001081900
2001081912 ...
..$ logrho: num [1:14] 1.16 -0.50 -0.50 -0.50 -0.50 ...
..$ w2: num [1:14] 1.01 1.27 1.18 1.23 1.17 ...
..$ rms : num [1:14] 5.00 1.40 1.26 1.36 1.25 ...
..$ maxi : num [1:14] 8.66 7.54 6.39 6.68 5.83 ...
$ log50:'data.frame': 69 obs. of 5 variables:
..$ DATE : int [1:69] 2001081500 2001081512 2001081600
2001081612
2001081700 2001081712 2001081800 2001081812 2001081900
2001081912 ...
..$ logrho: num [1:69] 1.16 -1.50 -1.50 -1.50 -1.50 ...
..$ w2: num [1:69] 1.01 1.27 1.25 1.33 1.31 ...
..$ rms : num [1:69] 5.001 0.516 0.516 0.577 0.554 ...
..$ maxi : num [1:69] 8.66 2.77 3.44 2.92 3.25 ...
$ log60:'data.frame': 66 obs. of 5 variables:
..$ DATE : int [1:66] 2001081500 2001081512 2001081600
2001081612
2001081700 2001081712 2001081800 2001081812 2001081900
2001081912 ...
..$ logrho: num [1:66] 1.16 -2.00 -2.00 -2.00 -2.00 ...
..$ w2: num [1:66] 1.01 1.27 1.27 1.34 1.34 ...
..$ rms : num [1:66] 5.001 0.313 0.326 0.371 0.366 ...
..$ maxi : num [1:66] 8.66 1.68 2.43 2.23 3.85 ...
sapply(dats,mean)
log20 log30 log40
log50 log60
DATE2.001088e+09 2.001087e+09 2.001082e+09 2.001087e+09
2.001086e+09
logrho -1.270326e+00 -9.695748e-01 -3.816967e-01 -1.461383e+00
-1.951941e+00
w2 1.324907e+00 1.283293e+00 1.217808e+00 1.345297e+00
1.398435e+00
rms 7.752963e-01 9.623266e-01 1.636949e+00 6.788993e-01
4.810029e-01
maxi4.016900e+00 4.466865e+00 6.205573e+00 3.672405e+00
2.898055e+00
sapply(dats,min)
log20 log30 log40 log50 log60
-1.3000708 -1.960 -0.5000176 -1.5001134 -2.0001350
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Re: [R] Is this sapply behaviour normal?
Rolf Turner wrote:
>
> The answer to your question is ``yeah, sort of''. The reason for the
> difference is that mean() is generic and has a method for data frames,
> according to which the mean of each column of the data frame is found
> in some ``appropriate'' manner. (Essentially the columns of the data
> frame must be either numeric or have some sort of date persuasion, else
> you get a warning and an NA for the column in question. The function
> min()
> is not generic and so if you hit a data frame with min() it (apparently)
> treats that data frame as if it were an atomic vector of data and finds
> the minimum of that atomic vector. Given, of course, that doing so makes
> sense.
>
> It would seem that you want min() to mimic the behaviour of mean(). To
> achieve this you can, in this instance at least (I think!) simply do
>
> sapply(dats,function(x){sapply(x,min)})
you can achieve the same with
sapply(dats, sapply, min)
vQ
__
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Re: [R] Is this sapply behaviour normal?
On Thu, Jun 26, 2008 at 12:14 AM, Wacek Kusnierczyk <
[EMAIL PROTECTED]> wrote:
> >
> > sapply(dats,function(x){sapply(x,min)})
>
> you can achieve the same with
>
> sapply(dats, sapply, min)
>
>
Did you actually try it?
> dats <- data.frame(1:10,2:11)
> sapply(dats,sapply,min)
X1.10 X2.11
[1,] 1 2
[2,] 2 3
[3,] 3 4
[4,] 4 5
[5,] 5 6
[6,] 6 7
[7,] 7 8
[8,] 8 9
[9,] 910
[10,]1011
Sapply doesn't (or can't?) pass arguments to another sapply -- maybe the
trick can be done without an anonymous function but not the way you
suggested.
Kenn
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Re: [R] Is this sapply behaviour normal?
Kenn Konstabel wrote:
> On Thu, Jun 26, 2008 at 12:14 AM, Wacek Kusnierczyk <
> [EMAIL PROTECTED]> wrote:
>
>
>>> sapply(dats,function(x){sapply(x,min)})
>>>
>> you can achieve the same with
>>
>> sapply(dats, sapply, min)
>>
>>
>>
> Did you actually try it?
>
>
>> dats <- data.frame(1:10,2:11)
>> sapply(dats,sapply,min)
>>
> X1.10 X2.11
> [1,] 1 2
> [2,] 2 3
> [3,] 3 4
> [4,] 4 5
> [5,] 5 6
> [6,] 6 7
> [7,] 7 8
> [8,] 8 9
> [9,] 910
> [10,]1011
>
> Sapply doesn't (or can't?) pass arguments to another sapply -- maybe the
> trick can be done without an anonymous function but not the way you
> suggested.
>
>
did you actually read the original mail? there dats was a *list* of
data frames.
try this:
d = data.frame(a=1:10. b=11:20)
l = list(a=d, b=d)
sapply(l, sapply, min)
sapply(l. function(d) sapply(d, min))
did you actually read the docs for sapply? there ... stands for
optional arguments to FUN.
try this:
?sapply
vQ
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Re: [R] Is this sapply behaviour normal?
Sorry, my mistake, - it works both ways with a correct example and neither
way with the wrong example.
k
On Thu, Jun 26, 2008 at 4:25 PM, Wacek Kusnierczyk <
[EMAIL PROTECTED]> wrote:
> >>> sapply(dats,function(x){sapply(x,min)})
> >>>
> >> you can achieve the same with
> >>
> >> sapply(dats, sapply, min)
> >>
> >>
> >>
> > Did you actually try it?
> >
> >
> >> dats <- data.frame(1:10,2:11)
> >> sapply(dats,sapply,min)
> >>
> > X1.10 X2.11
> > [1,] 1 2
> > [2,] 2 3
> > [3,] 3 4
> > [4,] 4 5
> > [5,] 5 6
> > [6,] 6 7
> > [7,] 7 8
> > [8,] 8 9
> > [9,] 910
> > [10,]1011
> >
> > Sapply doesn't (or can't?) pass arguments to another sapply -- maybe the
> > trick can be done without an anonymous function but not the way you
> > suggested.
> >
> >
>
> did you actually read the original mail? there dats was a *list* of
> data frames.
> try this:
>
> d = data.frame(a=1:10. b=11:20)
> l = list(a=d, b=d)
> sapply(l, sapply, min)
> sapply(l. function(d) sapply(d, min))
>
> did you actually read the docs for sapply? there ... stands for
> optional arguments to FUN.
> try this:
>
> ?sapply
>
>
> vQ
>
> __
> R-help@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.
>
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