I implemented in R a function to re-create the CDC Growth Chart, according to the data provided by the CDC.In order to use this function, you need to download the .rar file available at this megaupload link.Mirror: mediafire link.Then unrar the file, a...

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Capabilities of R are definitely unless! After my previous posts about some easy image editing in R (they are here, and here), now is the time to explore if R is capable of sound editing!

Just for fun, here I created a function that receives a phone number (or another sequence of numbers), and returns the equivalent melody...

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Here I implemented in R some dithering algorithms:
- Floyd-Steinberg dithering
- Bill Atkinson dithering
- Jarvis-Judice-Ninke dithering
- Sierra 2-4a dithering
- Stucki dithering
- Burkes dithering
- Sierra2 dithering
- Sierra3 dithering

For each algorithm, I wrote a 2-dimensional convolution function (a matrix passing over a matrix); it is slow because I didn't implemented any fasting tricks. It can be easily implemented in C, then used...

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Benford's law, also called the first-digit law, states that in lists of numbers from many (but not all) real-life sources of data, the leading digit is distributed in a specific, non-uniform way. According to this law, the first digit is 1 about 30% of the time, and larger digits occur as the leading digit with lower and lower frequency,...

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x y
# plot scatterplot and the regression line
mod1 plot(x, y, xlim=c(min(x)-5, max(x)+5), ylim=c(min(y)-10, max(y)+10))
abline(mod1, lwd=2)



# calculate residuals and predicted values
res pre
# plot distances between points and the regression line
segments(x, y, x, pre, col="red")

# add labels (res values) to points
library(calibrate)
textxy(x, y, res, cx=0.7)


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Here I present some functions I wrote to recreate some of the most common image effect available in all image editor.
They require the library rimage.
To load the image, use:

y <- read.jpeg("path")

plot(y)

rgb2sepia <- function(img){
 iRed <- img*255
 iGreen <- img*255
 iBlue <- img*255
 
 oRed <- iRed * .393...
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Here I present some functions I wrote to recreate some of the most common image effect available in all image editor.
They require the library rimage.
To load the image, use:

y <- read.jpeg("path")

plot(y)

rgb2sepia <- function(img){
 iRed <- img*255
 iGreen <- img*255
 iBlue <- img*255
 
 oRed <- iRed * .393...
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Very similar to what has been done to create a function to perform fast multiplication of large matrices using the Strassen algorithm (see previous post), now we write the functions to quickly calculate the inverse of a matrix.

To avoid rewriting pages and pages of comments and formulas, as I did for matrix multiplication, this time I'll...

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Very similar to what has been done to create a function to perform fast multiplication of large matrices using the Strassen algorithm (see previous post), now we write the functions to quickly calculate the inverse of a matrix.

To avoid rewriting pages and pages of comments and formulas, as I did for matrix multiplication, this time I'll...

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I tried to implement the Strassen's algorithm for big matrices multiplication in R.Here I present a pdf with some theory element, some example and a possible solution in R.I'm not a programmer, so the function is not optimize, but it works.I want to th...

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