Am 15.10.20 um 23:04 schrieb ddka:

Hello,

I'm in need of an efficient network format for frontend code, and I figured that since you already have one I shouldn't reinvent the wheel. I'm currently trying to implement it with Node + Typescript. I'm reading the docs page for the format carefully, but I'm stuck at a point. I'm not used to working at the level of bytes so if this is a waste of time, I'm sorry.

I'm using the "7th graders" graph from ns as an example. Everything is working fine up to the number of nodes:

    {
      magicString: '⛾ gt',
      version: 1,
      bigEndian: false,
      stringLength: 216,
      commentString: 'graph-tool binary file (http:://graph-tool.skewed.de)
generated by version 2.34dev (commit 1f792136, Thu Jul 2 23:05:34 2020
+0200) stats: 29 vertices, 740 edges, directed, 6 graph props, 2 vertex
props, 2 edge props',
      directed: true,
      numNodes: 29,
      usedBytesForNodeIndex: 1
    }

But, for grabbing the neighbors for every node I'm stuck. I can read the number of neighbors for the first node properly: 22. But, this is giving nonsense when I read it as LE, but it's working as BE, even though Big-Endian byte in the beginning was 0? That's my first source of confusion.

Next, after reading that 64bit int I move the offset forward by 8 and start reading the neighbors (each consuming 1 byte because numNodes = 29 < 64?). I get: "[0, 0, 0, 0, 0, 0, 0, 5, 7, 10, 11, 13, 15, 16, 18, 20, 21, 25, 26, 7, 10, 11]". Clearly I'm messing something up here. It's misaligned by 7 bytes. If I move the offset forward by 7 I get the proper "[5, 7, 10, 11, 13, 15, 16, 18, 20, 21, 25, 26, 7, 10, 11, 1, 4, 5, 10, 11, 13, 15]". And, the number of nodes I read for the second vertex is garbage.

I'm doing something wrong at this point. Sorry if this is obvious and I'm wasting time. Any idea what I'm missing here?

If you are trying to implement a gt reader, and you are running into problems parsing an existing file, you need to provide an actual minimal working example that yields the problem you are having. Just describing in words what you are trying to do is a complete non-starter.

A side observation: If you are implementing a gt reader in Javascript, it is not very likely that you will get much speed improvement over graphml/gml. Significant improvements will only be seen if implementing in C/C++.

Best, Tiago