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December 24, 2008 20:11
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load the MNIST data set in R
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# Load the MNIST digit recognition dataset into R | |
# http://yann.lecun.com/exdb/mnist/ | |
# assume you have all 4 files and gunzip'd them | |
# creates train$n, train$x, train$y and test$n, test$x, test$y | |
# e.g. train$x is a 60000 x 784 matrix, each row is one digit (28x28) | |
# call: show_digit(train$x[5,]) to see a digit. | |
# brendan o'connor - gist.github.com/39760 - anyall.org | |
load_mnist <- function() { | |
load_image_file <- function(filename) { | |
ret = list() | |
f = file(filename,'rb') | |
readBin(f,'integer',n=1,size=4,endian='big') | |
ret$n = readBin(f,'integer',n=1,size=4,endian='big') | |
nrow = readBin(f,'integer',n=1,size=4,endian='big') | |
ncol = readBin(f,'integer',n=1,size=4,endian='big') | |
x = readBin(f,'integer',n=ret$n*nrow*ncol,size=1,signed=F) | |
ret$x = matrix(x, ncol=nrow*ncol, byrow=T) | |
close(f) | |
ret | |
} | |
load_label_file <- function(filename) { | |
f = file(filename,'rb') | |
readBin(f,'integer',n=1,size=4,endian='big') | |
n = readBin(f,'integer',n=1,size=4,endian='big') | |
y = readBin(f,'integer',n=n,size=1,signed=F) | |
close(f) | |
y | |
} | |
train <<- load_image_file('mnist/train-images-idx3-ubyte') | |
test <<- load_image_file('mnist/t10k-images-idx3-ubyte') | |
train$y <<- load_label_file('mnist/train-labels-idx1-ubyte') | |
test$y <<- load_label_file('mnist/t10k-labels-idx1-ubyte') | |
} | |
show_digit <- function(arr784, col=gray(12:1/12), ...) { | |
image(matrix(arr784, nrow=28)[,28:1], col=col, ...) | |
} |
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Very nice!