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@brendano
Created December 24, 2008 20:11
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load the MNIST data set in R
# 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, ...)
}
@gao157
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gao157 commented May 22, 2019

Very nice!

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