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Read in 4-byte words from binary file in Julia

I have a simple binary file that contains 32-bit floats adjacent to each other.

Using Julia, I would like to read each number (i.e. each 32-bit word) and put them each sequentially into a array of Float32 format.

I've tried a few different things through looking at the documentation, but all have yielded impossible values (I am using a binary file with known values as dummy input). It appears that:

  1. Julia is reading the binary file one-byte at a time.

  2. Julia is putting each byte into a Uint8 array.

For example, readbytes(f, 4) gives a 4-element array of unsigned 8-bit integers. read(f, Float32, DIM) also gives strange values.

Anyone have any idea how I should proceed?

Solution

  • Julia Language has changed a lot since 5 years ago. read() no longer has API to specify Type and length simultaneously. reinterpret() creates a view of a binary array instead of array with desired type. It seems that now the best way to do this is to pre-allocate the desired array and fill it with read!:

    data = Array{Float32, 1}(undef, 128)
read!(io, data)

    This fills data with desired float numbers.