Re: [R] How to sum a function over a specific range in R?
You should cc r-help on all correspondence, so others can follow the thread.
Here is a very simple example of a home-made smooth function. Perhaps you
can modify it to suit your needs.
Jean
# simple smooth function, using a weighted mean
smoothfunction - function(allxs, allys, centerindex, halfwidth) {
distfromcenter - abs(allxs - allxs[centerindex])
weight - ifelse(distfromcenter = halfwidth, 1/(distfromcenter+1), 0)
weighted.mean(allys, weight)
}
# fake data
x - runif(1000)
y - 3*x^2 + x + rnorm(1000)
# set desired halfwidth of window for smooth
halfwid - 0.1
# determine the smoothed value of y for each value of x
L - length(x)
smoothedy - numeric(L)
for(i in 1:L) {
smoothedy[i] - smoothfunction(x, y, i, halfwid)
}
# plot the results
plot(x, y)
lines(x[order(x)], smoothedy[order(x)], lwd=3)
On Wed, Nov 13, 2013 at 5:59 PM, umair durrani umairdurr...@outlook.comwrote:
*Thanks Jeanat-least someone replied. I have gone through the link you
provided but the real problem is that it is more complex to understand
than the R documentation. Actually, I don't have any background in noise
reduction / smoothing of data. Can you guide me how I could just apply the
equation included in my question?*
*best regards,*
*Umair Durrani*
*email: umairdurr...@outlook.com umairdurr...@hotmail.com*
--
From: jvad...@usgs.gov
Date: Wed, 13 Nov 2013 15:10:07 -0600
Subject: Re: [R] How to sum a function over a specific range in R?
To: umairdurr...@outlook.com
CC: r-help@r-project.org
On Tue, Nov 12, 2013 at 11:45 AM, umair durrani
umairdurr...@outlook.comwrote:
I am new to R and have already posted this question on stack overflow. The
problem is that I did not understand the answers as the R documentation
about the discussed functions (e.g. 'convolve') is quite complicated for a
newbie like me. Here's the question:
I have a big text file with more than 3 million rows. The following is the
example of the three columns I want to use:
indxvehID LocalY
1 2 35.381
2 2 39.381
3 2 43.381
4 2 47.38
5 2 51.381
6 2 55.381
7 2 59.381
8 2 63.379
9 2 67.383
10 2 71.398
where,indx = IndexvehID = Vehicle ID (Here only '2' is shown but infact
there are 2169 vehicle IDs and each one repeats several times because the
data was collected at every 0.1 seconds)LocalY = The y coordinate of the
vehicle at a particular time (The time column is not shown here)
What I want to do is to create a new column of 'SmoothedY' using the
following formula:
SmoothedY = 1/Z * Summation from (i-15) to (i+15) (LocalY *
exp(-abs(i-k))/5))
where,i = indxZ = Summation from (k =i-15) to (k = i+15) (
exp(-abs(i-k))/5))
How can I apply this formula to create the new column 'SmoothedY'? This is
actually a data smoothing problem but default smoothing algorithms in R are
not suitable for my data and I have to use this custom formula.
Thanks in advance.
Umair Durrani
I have never tried this myself, but it appears as if you can define your
own smoothing function using Simon Wood's mgcv package. Check out
http://www.maths.bath.ac.uk/~sw283/talks/snw-R-talk.pdf for more
information.
Jean
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Re: [R] How to sum a function over a specific range in R?
On Tue, Nov 12, 2013 at 11:45 AM, umair durrani umairdurr...@outlook.comwrote: I am new to R and have already posted this question on stack overflow. The problem is that I did not understand the answers as the R documentation about the discussed functions (e.g. 'convolve') is quite complicated for a newbie like me. Here's the question: I have a big text file with more than 3 million rows. The following is the example of the three columns I want to use: indxvehID LocalY 1 2 35.381 2 2 39.381 3 2 43.381 4 2 47.38 5 2 51.381 6 2 55.381 7 2 59.381 8 2 63.379 9 2 67.383 10 2 71.398 where,indx = IndexvehID = Vehicle ID (Here only '2' is shown but infact there are 2169 vehicle IDs and each one repeats several times because the data was collected at every 0.1 seconds)LocalY = The y coordinate of the vehicle at a particular time (The time column is not shown here) What I want to do is to create a new column of 'SmoothedY' using the following formula: SmoothedY = 1/Z * Summation from (i-15) to (i+15) (LocalY * exp(-abs(i-k))/5)) where,i = indxZ = Summation from (k =i-15) to (k = i+15) ( exp(-abs(i-k))/5)) How can I apply this formula to create the new column 'SmoothedY'? This is actually a data smoothing problem but default smoothing algorithms in R are not suitable for my data and I have to use this custom formula. Thanks in advance. Umair Durrani I have never tried this myself, but it appears as if you can define your own smoothing function using Simon Wood's mgcv package. Check out http://www.maths.bath.ac.uk/~sw283/talks/snw-R-talk.pdf for more information. Jean [[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] How to sum a function over a specific range in R?
?filter perhaps. -- Bert On Wed, Nov 13, 2013 at 1:10 PM, Adams, Jean jvad...@usgs.gov wrote: On Tue, Nov 12, 2013 at 11:45 AM, umair durrani umairdurr...@outlook.comwrote: I am new to R and have already posted this question on stack overflow. The problem is that I did not understand the answers as the R documentation about the discussed functions (e.g. 'convolve') is quite complicated for a newbie like me. Here's the question: I have a big text file with more than 3 million rows. The following is the example of the three columns I want to use: indxvehID LocalY 1 2 35.381 2 2 39.381 3 2 43.381 4 2 47.38 5 2 51.381 6 2 55.381 7 2 59.381 8 2 63.379 9 2 67.383 10 2 71.398 where,indx = IndexvehID = Vehicle ID (Here only '2' is shown but infact there are 2169 vehicle IDs and each one repeats several times because the data was collected at every 0.1 seconds)LocalY = The y coordinate of the vehicle at a particular time (The time column is not shown here) What I want to do is to create a new column of 'SmoothedY' using the following formula: SmoothedY = 1/Z * Summation from (i-15) to (i+15) (LocalY * exp(-abs(i-k))/5)) where,i = indxZ = Summation from (k =i-15) to (k = i+15) ( exp(-abs(i-k))/5)) How can I apply this formula to create the new column 'SmoothedY'? This is actually a data smoothing problem but default smoothing algorithms in R are not suitable for my data and I have to use this custom formula. Thanks in advance. Umair Durrani I have never tried this myself, but it appears as if you can define your own smoothing function using Simon Wood's mgcv package. Check out http://www.maths.bath.ac.uk/~sw283/talks/snw-R-talk.pdf for more information. Jean [[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. -- Bert Gunter Genentech Nonclinical Biostatistics (650) 467-7374 __ 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.
[R] How to sum a function over a specific range in R?
I am new to R and have already posted this question on stack overflow. The problem is that I did not understand the answers as the R documentation about the discussed functions (e.g. 'convolve') is quite complicated for a newbie like me. Here's the question: I have a big text file with more than 3 million rows. The following is the example of the three columns I want to use: indxvehID LocalY 1 2 35.381 2 2 39.381 3 2 43.381 4 2 47.38 5 2 51.381 6 2 55.381 7 2 59.381 8 2 63.379 9 2 67.383 10 2 71.398 where,indx = IndexvehID = Vehicle ID (Here only '2' is shown but infact there are 2169 vehicle IDs and each one repeats several times because the data was collected at every 0.1 seconds)LocalY = The y coordinate of the vehicle at a particular time (The time column is not shown here) What I want to do is to create a new column of 'SmoothedY' using the following formula: SmoothedY = 1/Z * Summation from (i-15) to (i+15) (LocalY * exp(-abs(i-k))/5)) where,i = indxZ = Summation from (k =i-15) to (k = i+15) ( exp(-abs(i-k))/5)) How can I apply this formula to create the new column 'SmoothedY'? This is actually a data smoothing problem but default smoothing algorithms in R are not suitable for my data and I have to use this custom formula. Thanks in advance. Umair Durrani [[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.
