[R] Smoothing Data-dplyr

David Winsemius dwinsemius at comcast.net
Sat Oct 18 17:59:10 CEST 2014 

On Oct 18, 2014, at 7:57 AM, umair durrani wrote:

> Please note that I have already asked this question on stackoverflow.com but did not get a satisfactory answer.

You should say what was unsatisfactory about the answer you were offered:
http://stackoverflow.com/questions/26434652/data-smoothing-in-r

You got 3 answers that appeared to be improvements including one using Rcpp that gave you a 6 thousand fold improvement in running time.

-- 
David.

> I have a data set containing velocities of 2169 vehicles recorded at 
> intervals of 0.1 seconds. So, there are many rows for an individual 
> vehicle. Here I am reproducing the data only for the vehicle # 2:   
>> dput(uma)
> structure(list(Vehicle.ID = c(2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 
> 2, 2), Frame.ID = 13:445, Vehicle.velocity = c(40, 40, 40, 40, 
> 40, 40, 40, 40.02, 40.03, 39.93, 39.61, 39.14, 38.61, 38.28, 
> 38.42, 38.78, 38.92, 38.54, 37.51, 36.34, 35.5, 35.08, 34.96, 
> 34.98, 35, 34.99, 34.98, 35.1, 35.49, 36.2, 37.15, 38.12, 38.76, 
> 38.95, 38.95, 38.99, 39.18, 39.34, 39.2, 38.89, 38.73, 38.88, 
> 39.28, 39.68, 39.94, 40.02, 40, 39.99, 39.99, 39.65, 38.92, 38.52, 
> 38.8, 39.72, 40.76, 41.07, 40.8, 40.59, 40.75, 41.38, 42.37, 
> 43.37, 44.06, 44.29, 44.13, 43.9, 43.92, 44.21, 44.59, 44.87, 
> 44.99, 45.01, 45.01, 45, 45, 45, 44.79, 44.32, 43.98, 43.97, 
> 44.29, 44.76, 45.06, 45.36, 45.92, 46.6, 47.05, 47.05, 46.6, 
> 45.92, 45.36, 45.06, 44.96, 44.97, 44.99, 44.99, 44.99, 44.99, 
> 45.01, 45.02, 44.9, 44.46, 43.62, 42.47, 41.41, 40.72, 40.49, 
> 40.6, 40.76, 40.72, 40.5, 40.38, 40.43, 40.38, 39.83, 38.59, 
> 37.02, 35.73, 35.04, 34.85, 34.91, 34.99, 34.99, 34.97, 34.96, 
> 34.98, 35.07, 35.29, 35.54, 35.67, 35.63, 35.53, 35.53, 35.63, 
> 35.68, 35.55, 35.28, 35.06, 35.09, 35.49, 36.22, 37.08, 37.8, 
> 38.3, 38.73, 39.18, 39.62, 39.83, 39.73, 39.58, 39.57, 39.71, 
> 39.91, 40, 39.98, 39.97, 40.08, 40.38, 40.81, 41.27, 41.69, 42.2, 
> 42.92, 43.77, 44.49, 44.9, 45.03, 45.01, 45, 45, 45, 45, 45, 
> 45, 45, 45, 45, 45, 45, 44.99, 45.03, 45.26, 45.83, 46.83, 48.2, 
> 49.68, 50.95, 51.83, 52.19, 52, 51.35, 50.38, 49.38, 48.63, 48.15, 
> 47.87, 47.78, 48.01, 48.63, 49.52, 50.39, 50.9, 50.96, 50.68, 
> 50.3, 50.05, 49.94, 49.87, 49.82, 49.82, 49.88, 49.96, 50, 50, 
> 49.98, 49.98, 50.16, 50.64, 51.43, 52.33, 53.01, 53.27, 53.22, 
> 53.25, 53.75, 54.86, 56.36, 57.64, 58.28, 58.29, 57.94, 57.51, 
> 57.07, 56.64, 56.43, 56.73, 57.5, 58.27, 58.55, 58.32, 57.99, 
> 57.89, 57.92, 57.74, 57.12, 56.24, 55.51, 55.1, 54.97, 54.98, 
> 55.02, 55.03, 54.86, 54.3, 53.25, 51.8, 50.36, 49.41, 49.06, 
> 49.17, 49.4, 49.51, 49.52, 49.51, 49.45, 49.24, 48.84, 48.29, 
> 47.74, 47.33, 47.12, 47.06, 47.07, 47.08, 47.05, 47.04, 47.25, 
> 47.68, 47.93, 47.56, 46.31, 44.43, 42.7, 41.56, 41.03, 40.92, 
> 40.92, 40.98, 41.19, 41.45, 41.54, 41.32, 40.85, 40.37, 40.09, 
> 39.99, 39.99, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 39.98, 
> 39.97, 40.1, 40.53, 41.36, 42.52, 43.71, 44.57, 45.01, 45.1, 
> 45.04, 45, 45, 45, 45, 45, 45, 44.98, 44.97, 45.08, 45.39, 45.85, 
> 46.2, 46.28, 46.21, 46.29, 46.74, 47.49, 48.35, 49.11, 49.63, 
> 49.89, 49.94, 49.97, 50.14, 50.44, 50.78, 51.03, 51.12, 51.05, 
> 50.85, 50.56, 50.26, 50.06, 50.1, 50.52, 51.36, 52.5, 53.63, 
> 54.46, 54.9, 55.03, 55.09, 55.23, 55.35, 55.35, 55.23, 55.07, 
> 54.99, 54.98, 54.97, 55.06, 55.37, 55.91, 56.66, 57.42, 58.07, 
> 58.7, 59.24, 59.67, 59.95, 60.02, 60, 60, 60, 60, 60, 60.01, 
> 60.06, 60.23, 60.65, 61.34, 62.17, 62.93, 63.53, 64, 64.41, 64.75, 
> 65.04, 65.3, 65.57, 65.75, 65.74, 65.66, 65.62, 65.71, 65.91, 
> 66.1, 66.26, 66.44, 66.61, 66.78, 66.91, 66.99, 66.91, 66.7, 
> 66.56, 66.6, 66.83, 67.17, 67.45, 67.75, 68.15, 68.64, 69.15, 
> 69.57, 69.79, 69.79, 69.72, 69.72, 69.81, 69.94, 70, 70.01, 70.02, 
> 70.03)), row.names = c(NA, 433L), class = "data.frame", .Names = c("Vehicle.ID", 
> "Frame.ID", "Vehicle.velocity"))  
> I am trying to smooth the data using dplyr. Here is the code:  
> uma <- tbl_df(uma)
>    uma <- uma %>%     # take data frame 
>      group_by(Vehicle.ID)  %>%  # group by Vehicle ID
>      mutate(i = 1:length(Frame.ID), im1 = i-1, Nai = length(Frame.ID) - i,
>             Dv = pmin(im1, Nai, 30),
>             imDv = i - Dv,
>             ipDv = i + Dv) %>%  # finding i, i-1 and Nalpha-i, D, i-D and i+D for location, velocity and acceleration
>      ungroup()  
> 
> 
>    umav <- uma %>%
>      group_by(Vehicle.ID, Frame.ID) %>%
>      do(data.frame(kv = .$imDv:.$ipDv)) %>%
>      left_join(x=., y=uma) %>%
>      mutate(imk = i - kv, aimk = (-1) * abs(imk), delta = 10, kernel = exp(aimk/delta)) %>%
>      ungroup() %>%
>      group_by(Vehicle.ID) %>%
>      mutate(p = Vehicle.velocity2[match(kv,i)], kernelp = p * kernel) %>%
>      ungroup() %>%
>      group_by(Vehicle.ID, Frame.ID) %>%
>      summarise(Z = sum(kernel), prod = sum(kernelp)) %>%
>      mutate(svel = prod/Z) %>%
>      ungroup()
> 
> The code works but takes 1 hour. I think the delay is caused by do(data.frame(kv = .$imDv:.$ipDv)). Is there any faster way to do this?
> 		 	   		  
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David Winsemius
Alameda, CA, USA

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