[R] Regression

2006-11-15 Thread Alvaro
I need to run a regression analysis with a large number of samples. Each
sample (identified in the first file column) has its own x and y values. I
will use the same model in all samples. How can I run the model for each
sample? In SAS code I would use the BY SAMPLE statement.

 

Alvaro

 

 


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[R] tree-ring response function in R?

2006-07-10 Thread Alvaro Gutierrez
Hi,

I am looking forward if some of you could help me with this. I have been 
looking R-functions to conduct tree-ring analysis in R. I  know that exists 
a COFECHA version in R developed by C. Bigler. But I don't know if is there 
another collection of functions to do dendroclimatological analysis (such as 
response functions). Has someone developed such rutines in R ?,

thanks in advance,

Alvaro

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Re: [R] Generation of missiing values in a time serie...

2005-12-15 Thread Alvaro Saurin

On 13 Dec 2005, at 20:06, Gabor Grothendieck wrote:

 In thinking about this some more, the trick I discussed is
 probably not the best way to do it since its possible that
 in the future zoo will completely disallow illegal zoo objects.
 I think a better way might be to construct it like this:


 aggregate(zoo(z.data), round(z.time, 1), tail, 1)

 where z.data is the matrix and z.time are the times.  The variable
 z, which is an illegal zoo object, would not be created but in terms
 of z, since that is what I have reproducibly from your post, we have:

 z.data - coredata(z)
 z.time - time(z)

Thanks for your help. However, I have finally implemented a solution  
by myself, using a loop that iterates over the original serie. I  
haven't been able to find a way of using these functions and  
generating a regular time serie in the way I wanted. Thanks anyway.

Alvaro


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Re: [R] Generation of missiing values in a time serie...

2005-12-13 Thread Alvaro Saurin

Hi,

First, thank you. It 'almost' works: I can convert a matrix to a  
'zoo' object, but it can not convert it to a 'ts'.

The sitruation is this: I load a set of samples with

   h_types - list (0, 0, character(0), character(0), 0, 0, 0, 0, 0)
   h_names - list (time, flow, type, dir, seq, ts, x,  
rtt, size)
   pcks_file   - pipe (grep ' P '  server.dat), r)
   pcks- scan (pcks_file, what = h_types, comment.char = '#', 
   
fill = TRUE)
Read 1429 records

   mat - data.frame (pcks)
  colnames (mat)   - h_names
   mat

time flow type dir  seq ts x  rtt size
1  1.0008930P   +0   1.000893  1472 0.00 1472
2  1.5144540P   +1   1.514454  2944 0.513142 1472
3  2.0150930P   +2   2.015093  2944 0.513142 1472
4  2.5150250P   +3   2.515025  4806 0.504488 1472
5  2.8219760P   +4   2.821976  5730 0.496728 1472
6  3.0789310P   +5   3.078931  5832 0.489744 1472
7  3.3318970P   +6   3.331897  5832 0.489744 1472

[...]

1425 176.9255040P   + 1424 176.925504 12141 0.764699 1472
1426 177.0394890P   + 1425 177.039489 12141 0.764699 1472
1427 177.1534690P   + 1426 177.153469 12141 0.764699 1472
1428 177.2674640P   + 1427 177.267464 12141 0.764699 1472
1429 177.3814340P   + 1428 177.381434 12141 0.764699 1472

Then I convert it to a 'zoo', removing the 'time' column from the input

   last_col- ncol (mat)
   range_cols  - 2:last_col
   matrix_values   - mat [,range_cols]
   z - zoo (matrix_values, mat $ time)

So far, everything is fine. But then I need to apply a function to  
samples taken every t seconds, ie, the mean every 10 seconds. And,  
AFAIK, rapply needs a constant 'width', something that can only be  
obtained with regular time series... But if I try to get a 'ts'  
object from my 'zoo' I get

  as.ts (z)
Error in if (del == 0  to == 0) return(to) :
missing value where TRUE/FALSE needed

Ummm, do you know if there is any error in my 'zoo' object? Has it  
the right format? Or, could I avoid the conversion and use the  
'rapply' function but on time intervals (instead of points intervals)?

Thank you very much.

Alvaro


On 12 Dec 2005, at 16:31, Gabor Grothendieck wrote:

 First we generate some sample data x and its times tt.
 Then using the zoo package we create an irregularly
 spaced time series.  Now if you want a regularly spaced
 time series convert it to ts class.  After loading zoo as
 shown below, the R command vignette(zoo) gives more info.

 x - 1:4
 tt - c(1, 3, 4, 6)

 library(zoo)
 x.zoo - zoo(x, tt) # irregularly spaced time series
 x.ts - as.ts(x.zoo) # regular time series with NAs


 On 12/12/05, Alvaro Saurin [EMAIL PROTECTED] wrote:

 Hi,

 I am a R begginer and I have a small problem with time series. I was
 wondering if someone could help me

 I am collecting data from packets going through a network, and using
 R for obtaining some simple statistics of connections. However, my
 data is not collected at a constant frequency, so I would like to
 create a evenly spaced TS from my traces, using the minimum time
 difference between two samples as the period for my new TS, and
 filling  the gaps with NA (or 0s).

 I think ther must be some simple solution for this... Anyone could
 help me?

 Thanks in advance.

 --
 Alvaro Saurin [EMAIL PROTECTED] [EMAIL PROTECTED]

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Re: [R] Generation of missiing values in a time serie...

2005-12-13 Thread Alvaro Saurin

On 13 Dec 2005, at 13:08, Gabor Grothendieck wrote:

 Your variable mat is not a matrix; its a data frame.  Check it with:

class(mat)

 Here is an example:

 x - cbind(A = 1:4, B = 5:8)
 tt - c(1, 3:4, 6)

 library(zoo)
 x.zoo - zoo(x, tt)
 x.ts - as.ts(x.zoo)

Fixed, but anyway it fails:

   h_types - list (0, 0, NULL, NULL, 0, 0, 0, 0, 0)
   h_names - list (time, flow, seq, ts, x, rtt, size)

   pcks_file   - pipe (grep ' P ' server.dat, r)
   pcks- scan (pcks_file, what = h_types,
comment.char = '#', fill = TRUE)

   mat_df  - data.frame (pcks[1:2], pcks[5:9])
   mat - as.matrix (mat_df)
   colnames (mat)  - h_names  

   class (mat)
[1] matrix

   z - zoo (mat, mat [,time])

   z
   z
  time flow seq  ts
xrtt  size
1.0009   1.000893 0.00 0.00 1.000893   
1472.00 0.00  1472.00
1.5145   1.514454 0.00 1.00 1.514454   
2944.00 0.513142  1472.00
2.0151   2.015093 0.00 2.00 2.015093   
2944.00 0.513142  1472.00
2.5152.515025 0.00 3.00 2.515025   
4806.00 0.504488  1472.00
2.8222.821976 0.00 4.00 2.821976   
5730.00 0.496728  1472.00
[...]

   as.ts (z)
Error in if (del == 0  to == 0) return(to) :
missing value where TRUE/FALSE needed

Any idea? Thanks for your help.

Alvaro


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Re: [R] Generation of missiing values in a time serie...

2005-12-13 Thread Alvaro Saurin

I think I have found the error. It appears when there are two entries  
with the same time. Using as input file:

- CUT 
# Output format for PCKs:
# TIME FLOW P [+-] SEQ TS X RTT SIZE
#
123.125683 0 P + 967 123.125683 13394 0.798205 1472
123.241137 0 P + 968 123.241137 12680 0.796258 1472
123.241137 0 P + 969 123.241137 12680 0.796258 1472
123.472631 0 P + 970 123.472631 12680 0.796258 1472
123.588613 0 P + 971 123.588613 12680 0.796258 1472
123.704594 0 P + 972 123.704594 12680 0.796258 1472
- CUT 

I run fhe following code:

- CUT 
h_types - list (0, 0, NULL, NULL, 0, 0, 0, 0, 0)
h_names - list (time, flow,  seq, ts, x, rtt, size)

pcks_file- pipe (grep ' P ' data, r)
pcks  - scan (pcks_file, what = h_types, comment.char = '#',  
fill = TRUE)
mat_df  - data.frame (pcks[1:2], pcks[5:9])
mat   - as.matrix (mat_df)
colnames (mat)  - h_names
z - zoo (mat, mat [,time])
- CUT 

The dput of 'z' shows:

- CUT 
structure(c(123.125683, 123.241137, 123.241137, 123.472631, 123.588613,
123.704594, 0, 0, 0, 0, 0, 0, 967, 968, 969, 970, 971, 972, 123.125683,
123.241137, 123.241137, 123.472631, 123.588613, 123.704594, 13394,
12680, 12680, 12680, 12680, 12680, 0.798205, 0.796258, 0.796258,
0.796258, 0.796258, 0.796258, 1472, 1472, 1472, 1472, 1472, 1472
), .Dim = c(6, 7), .Dimnames = list(c(1, 2, 3, 4, 5,
6), c(time, flow, seq, ts, x, rtt, size)), index =  
structure(c(123.125683,
123.241137, 123.241137, 123.472631, 123.588613, 123.704594), .Names =  
c(1,
2, 3, 4, 5, 6)), class = zoo)
- CUT 

If I try a 'as.ts(z)', it fails. If I remove the duplicate entry, I  
can convert it to a TS with no problem. Is this made intentionally?  
Because then I have to filter the input matrix... But, anyway, the  
output matrix, after filtering, doesn't seem regular:

- CUT 
  as.ts (z)
Time Series:
Start = 1
End = 5
Frequency = 1
   time flow seq   ts x  rtt size
1 123.12570 967 123.1257 13394 0.798205 1472
2 123.24110 969 123.2411 12680 0.796258 1472
3 123.47260 970 123.4726 12680 0.796258 1472
4 123.58860 971 123.5886 12680 0.796258 1472
5 123.70460 972 123.7046 12680 0.796258 1472
Warning message:
‘x’ does not have an underlying regularity in: as.ts.zoo(z)
- CUT 

Weird...


On 13 Dec 2005, at 16:33, Gabor Grothendieck wrote:

 Please provide a reproducible example.  Note that dput(x) will output
 an R object in a way that can be copied and pasted into another  
 session.

 On 12/13/05, Alvaro Saurin [EMAIL PROTECTED] wrote:

 On 13 Dec 2005, at 13:08, Gabor Grothendieck wrote:

 Your variable mat is not a matrix; its a data frame.  Check it with:

class(mat)

 Here is an example:

 x - cbind(A = 1:4, B = 5:8)
 tt - c(1, 3:4, 6)

 library(zoo)
 x.zoo - zoo(x, tt)
 x.ts - as.ts(x.zoo)

 Fixed, but anyway it fails:

  h_types - list (0, 0, NULL, NULL, 0, 0, 0, 0, 0)
  h_names - list (time, flow, seq, ts, x, rtt,  
 size)

  pcks_file   - pipe (grep ' P ' server.dat, r)
  pcks- scan (pcks_file, what = h_types,
comment.char = '#', fill =  
 TRUE)

  mat_df  - data.frame (pcks[1:2], pcks[5:9])
  mat - as.matrix (mat_df)
  colnames (mat)  - h_names

  class (mat)
 [1] matrix

  z - zoo (mat, mat [,time])

  z
  z
  time flow seq  ts
 xrtt  size
 1.0009   1.000893 0.00 0.00 1.000893
 1472.00 0.00  1472.00
 1.5145   1.514454 0.00 1.00 1.514454
 2944.00 0.513142  1472.00
 2.0151   2.015093 0.00 2.00 2.015093
 2944.00 0.513142  1472.00
 2.5152.515025 0.00 3.00 2.515025
 4806.00 0.504488  1472.00
 2.8222.821976 0.00 4.00 2.821976
 5730.00 0.496728  1472.00
 [...]

  as.ts (z)
 Error in if (del == 0  to == 0) return(to) :
missing value where TRUE/FALSE needed

 Any idea? Thanks for your help.

 Alvaro


 --
 Alvaro Saurin [EMAIL PROTECTED] [EMAIL PROTECTED]





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[R] Generation of missiing values in a time serie...

2005-12-12 Thread Alvaro Saurin

Hi,

I am a R begginer and I have a small problem with time series. I was  
wondering if someone could help me

I am collecting data from packets going through a network, and using  
R for obtaining some simple statistics of connections. However, my  
data is not collected at a constant frequency, so I would like to  
create a evenly spaced TS from my traces, using the minimum time  
difference between two samples as the period for my new TS, and  
filling  the gaps with NA (or 0s).

I think ther must be some simple solution for this... Anyone could  
help me?

Thanks in advance.

-- 
Alvaro Saurin [EMAIL PROTECTED] [EMAIL PROTECTED]

__
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[R] Re: diamond graphs

2003-08-27 Thread Alvaro Muñoz
Drs. Harrell and O'Keefe,



Thank you for your suggestions.



Regarding your comments about the content of the paper, I respectfully
disagree that categorizing continuous variables is a fundamental violation
of statistical graphics, nor are you to assume that all categorizations are
arbitrary. In any case, the discussion section of our paper contains text
acknowledging that contour plots are a preferred option when the continuity
of variables is desired to be preserved. The hexagons we proposed seem, at
first glance, to be unnecessarily complex but they fulfill properties that
none of the other considered alternatives do (Table 1 and Figure 1 in paper
and Figure 6 using Trellis).



It is unfortunate that the comments from Dr. O'Keefe were based on a press
release and not on the manuscript itself. I apologize for the press release
implying no graphical progress in the 20th century. Many of his points are
addressed in the manuscript. Regarding the extension of the methods to
outcomes taking negative values (e.g., changes in markers), the use of two
colors is an alternative but the plotting of 0.5*[1+(outcome/max(|outcome|)]
and using the option E of Figure 1 in the paper will result in negative and
positive values having opposite topology (much as the contrast of
negative/positive bars in the unidimensional case). I will be happy to
expedite a reprint to Dr. O'Keefe. If you so desire, please email the
address to which it should be sent.



Although it is at odds with your beliefs, University staff working on
licensing and technology transfer believe that a patent may be a vehicle to
achieve a wide use. The audience of the proposed methods would be the end
users who are not sophisticated programmers and, therefore, the hope is that
it would be available in widely used software which is not the case of the
high end software (e.g., R). The proposed graph of 2D equiponderant display
of two predictors is just a display procedure, not an inferential tool. The
sophisticated analyst has little or no need for the proposed method. It does
overcome the pitfalls of 3D bar graphs and, therefore, has the potential of
improving the way we communicate our findings. Needless to say, were the
predictions of Dr. Harrell to be on target, we will change course as the
staff working on the licensing have planned from the start.



We will be happy to share the code we wrote to produce the figures in The
American Statistician paper with individuals wanting to use the software for
academic purposes. Please send request for it to [EMAIL PROTECTED]



In summary, our idea is a simple one (one that I refer as needing only 8th
grade geometry) and it is its simplicity which has been fun to peruse.



Alvaro Muñoz

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