scala-io read array of Ints

[marten luter]

Hello, what is the best way to read Array of Ints ( not Bytes )  from binary file using scala-io?

[Jesse Eichar]

In what way exactly? 

There are 2 answers I can see.  

1.  THe Java input stream way where each byte is converted to an integer

2.  The "correct" way where you take 4 bytes and convert it to an integer

Both ways are supported by scala-io.

The first would be:

input.bytesAsInts.foreach(i => // do something with integer)

For the second the solution is not as neat as for writing and it should be :(  I will work on that.

// convert to a LongTraversable[Int]

val integerTraversable = for { 

    // ByteProcessor creates ints and longs in Big-Endian  but you can 

    // convert it to an implementation to parse in Little-Endian 

   processor <- ByteProcessor(input.bytes.processor) 

    // call this so you process the entire input rather than just grab

    // first integer

    _ <- processor.repeatUntilEmpty  

} yield {

  processor.nextInt

}

integerTraversable.foreach( i => // do something with integer)

As with your last email.  It is clear to me this can be improved so I am creating a ticket about the verbosity of this fairly normal case.

Jesse

On Sat, Jun 1, 2013 at 6:37 PM, marten luter <ent...@googlemail.com> wrote:

Hello, what is the best way to read Array of Ints ( not Bytes )  from binary file using scala-io?

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[Jesse Eichar]

For the reading ints.  I forgot a simple obvious improvement  you can do the read and processing directly.

for { 

    // ByteProcessor creates ints and longs in Big-Endian  but you can 

    // convert it to an implementation to parse in Little-Endian 

   processor <- ByteProcessor(input.bytes.processor) 

    // call this so you process the entire input rather than just grab

    // first integer

    _ <- processor.repeatUntilEmpty  

}  {

  val i = processor.nextInt

// do something with int

}

In both cases there is only a single path through the data.

Probably more efficient would be to do:

input.blocks(Some(4)).foreach (block => // convert block to int and do something )

Jesse