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Binary file i/o in Julia
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# Write binary file | |
function write_bin(x::Array{T, 1}, fileName::String)::Int64 where T | |
# Open the file | |
io = open(fileName,"w") | |
# Cast this number to make sure we know its type | |
write(io, Int64(size(x)[1])) | |
# Get the type as a string | |
typ = repr(T) | |
# Write the length of the type string | |
write(io, Int64(length(typ))) | |
# Now write the type string | |
for i in eachindex(typ) | |
write(io, Char(typ[i])) | |
end | |
# Now write the array | |
for i in eachindex(x) | |
write(io, x[i]) | |
end | |
# Clean up | |
close(io) | |
return 0; | |
end | |
# Read binary file | |
# Sub Function which speeds up the read | |
function read_bin(io::IO, ::Type{T}, n::Int64) where T | |
# The array to be returned | |
x = Array{T, 1}(undef, n) | |
@time for i in eachindex(x) | |
x[i] = read(io, T) | |
end | |
close(io) | |
return x | |
end | |
# The read function | |
function read_bin(fileName::String) | |
# Open the file | |
io = open(fileName, "r") | |
# Read the total number of elements in the resulting array | |
n = read(io, Int64) | |
# Read the length of the type name | |
nt = read(io, Int64) | |
# println("Number of elements: $n") | |
# Then read the type name | |
cName = Array{Char}(undef, nt) | |
for i in eachindex(cName) | |
cName[i] = read(io, Char) | |
end | |
# The return type | |
T = eval(Symbol(String(cName))) | |
# The data | |
x = read_bin(io, T, n) | |
return x | |
end | |
function read_bin(fileName::String, ::Type{T}) where T | |
# Open the file | |
io = open(fileName, "r") | |
# Read the total number of elements in the resulting array | |
n = read(io, Int64) | |
# Read the length of the type name | |
nt = read(io, Int64) | |
# Then read the type name | |
cName = Array{Char}(undef, nt) | |
for i in eachindex(cName) | |
cName[i] = read(io, Char) | |
end | |
# The array to be returned | |
x = Array{T, 1}(undef, n) | |
@time for i in eachindex(x) | |
x[i] = read(io, T) | |
end | |
close(io) | |
return x | |
end | |
# Warm up | |
binFile = "data.bin" | |
n = 100; | |
arr1 = rand(Float64, n); | |
write_bin(arr1, binFile); | |
arr2 = read_bin(binFile); | |
arr3 = read_bin(binFile, eltype(arr1)); | |
rm(binFile) | |
# Timed write read | |
n = 100_000_000; | |
arr1 = rand(Float64, n); | |
@time write_bin(arr1, binFile); | |
arr2 = read_bin(binFile); | |
arr3 = read_bin(binFile, eltype(arr1)); | |
rm(binFile) |
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