jon.recoil.org
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My aggregated monorepo of OCaml code, automaintained
tessera-npy: edge case tests, polished docs, opam file
- Add trailing-comma (1D shape) and scalar shape edge case tests
- Comprehensive .mli documentation with usage example
- Auto-generated opam file
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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tessera-npy/lib/npy.mli
+64
-14
tessera-npy/lib/npy.mli
···
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(** Read and write numpy .npy files. *)
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(** Read numpy [.npy] files.
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A portable OCaml library for parsing the numpy binary format. Data is
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returned as flat {!Bigarray.Array1} values in C layout; use {!shape} to
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interpret the dimensions.
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{2 Supported dtypes}
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{ul
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{- [|i1] — signed 8-bit integer}
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{- [|u1] — unsigned 8-bit integer}
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{- [<f4] — 32-bit float (little-endian)}
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{- [<f8] — 64-bit float (little-endian)}}
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{2 Example}
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{[
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let data = In_channel.with_open_bin "embeddings.npy" In_channel.input_all in
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match Npy.of_string data with
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| Error msg -> failwith msg
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| Ok t ->
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let shape = Npy.shape t in
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Printf.printf "shape: %s\n"
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(String.concat "x" (Array.to_list (Array.map string_of_int shape)));
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match Npy.data_float32 t with
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| Some ba -> Printf.printf "first value: %f\n" (Bigarray.Array1.get ba 0)
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| None -> Printf.printf "not a float32 array\n"
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]} *)
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(** {1 Types} *)
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···
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| Float32 : float dtype
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| Float64 : float dtype
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(** A parsed .npy file: dtype, shape, and raw data as bytes. *)
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(** A parsed [.npy] file. *)
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type t
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(** {1 Reading} *)
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(** {1 Parsing} *)
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val of_string : string -> (t, string) result
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(** Parse a .npy file from its raw bytes. *)
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(** Parse a [.npy] file from its complete contents as a string. Supports
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format versions 1.0 and 2.0. Returns [Error msg] if the magic bytes are
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wrong, the header is malformed, or the dtype is unsupported. *)
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(** {1 Metadata} *)
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val shape : t -> int array
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(** The shape of the array. *)
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(** The shape of the array. For example, a 10x8 matrix returns [\[|10; 8|\]].
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A scalar returns [\[||\]]. *)
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val fortran_order : t -> bool
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(** Whether the data is in Fortran (column-major) order. *)
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(** Whether the data is stored in Fortran (column-major) order. Most numpy
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files use C order ([false]). *)
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(** {1 Data access}
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val data_int8 : t -> (int, Bigarray.int8_signed_elt, Bigarray.c_layout) Bigarray.Array1.t option
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(** Access data as int8 bigarray if the dtype matches. *)
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Each accessor returns [Some bigarray] if the dtype matches, or [None]
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otherwise. The returned {!Bigarray.Array1} is a flat (1-dimensional) view
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of the data in row-major order; use {!shape} to interpret the dimensions.
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For multi-dimensional indexing, compute the flat index as:
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[row * cols + col] (for 2D) or [i * (d1 * d2) + j * d2 + k] (for 3D). *)
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val data_int8 :
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t ->
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(int, Bigarray.int8_signed_elt, Bigarray.c_layout) Bigarray.Array1.t option
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(** Access data as signed 8-bit integers (numpy dtype [|i1]). *)
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val data_uint8 : t -> (int, Bigarray.int8_unsigned_elt, Bigarray.c_layout) Bigarray.Array1.t option
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(** Access data as uint8 bigarray if the dtype matches. *)
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val data_uint8 :
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t ->
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(int, Bigarray.int8_unsigned_elt, Bigarray.c_layout) Bigarray.Array1.t option
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(** Access data as unsigned 8-bit integers (numpy dtype [|u1]). *)
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val data_float32 : t -> (float, Bigarray.float32_elt, Bigarray.c_layout) Bigarray.Array1.t option
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(** Access data as float32 bigarray if the dtype matches. *)
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val data_float32 :
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t ->
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(float, Bigarray.float32_elt, Bigarray.c_layout) Bigarray.Array1.t option
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(** Access data as 32-bit floats (numpy dtype [<f4], little-endian). *)
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val data_float64 : t -> (float, Bigarray.float64_elt, Bigarray.c_layout) Bigarray.Array1.t option
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(** Access data as float64 bigarray if the dtype matches. *)
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val data_float64 :
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t ->
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(float, Bigarray.float64_elt, Bigarray.c_layout) Bigarray.Array1.t option
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(** Access data as 64-bit floats (numpy dtype [<f8], little-endian). *)
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tessera-npy/tessera-npy.install
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tessera-npy/tessera-npy.install
···
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lib: [
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"_build/install/default/lib/tessera-npy/META"
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"_build/install/default/lib/tessera-npy/dune-package"
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"_build/install/default/lib/tessera-npy/npy.a"
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"_build/install/default/lib/tessera-npy/npy.cma"
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"_build/install/default/lib/tessera-npy/npy.cmi"
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"_build/install/default/lib/tessera-npy/npy.cmt"
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"_build/install/default/lib/tessera-npy/npy.cmti"
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"_build/install/default/lib/tessera-npy/npy.cmx"
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"_build/install/default/lib/tessera-npy/npy.cmxa"
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"_build/install/default/lib/tessera-npy/npy.ml"
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"_build/install/default/lib/tessera-npy/npy.mli"
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"_build/install/default/lib/tessera-npy/opam"
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]
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libexec: [
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"_build/install/default/lib/tessera-npy/npy.cmxs"
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]
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tessera-npy/tessera-npy.opam
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tessera-npy/tessera-npy.opam
···
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# This file is generated by dune, edit dune-project instead
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opam-version: "2.0"
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synopsis: "Read and write numpy .npy files in OCaml"
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description:
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"A portable OCaml library for parsing the numpy .npy binary format. Supports int8, uint8, float32, and float64 dtypes with arbitrary shapes. Uses Bigarray for zero-copy data representation."
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license: "ISC"
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depends: [
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"dune" {>= "3.17"}
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"ocaml" {>= "5.2"}
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"alcotest" {with-test & >= "0.8"}
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"odoc" {with-doc}
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]
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build: [
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["dune" "subst"] {dev}
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[
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"dune"
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"build"
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"-p"
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name
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"-j"
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jobs
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"@install"
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"@runtest" {with-test}
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"@doc" {with-doc}
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]
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]
+48
tessera-npy/test/test_npy.ml
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tessera-npy/test/test_npy.ml
···
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if Float.abs (v -. 3.14) > 0.001 then
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Alcotest.failf "expected ~3.14, got %f" v)
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let make_npy_v1_raw header data =
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let prefix_len = 6 + 2 + 2 in
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let raw_header_len = String.length header + 1 in
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let padded_len =
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let total = prefix_len + raw_header_len in
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let rem = total mod 64 in
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if rem = 0 then raw_header_len else raw_header_len + (64 - rem)
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in
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let buf = Buffer.create (prefix_len + padded_len + String.length data) in
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Buffer.add_string buf "\x93NUMPY\x01\x00";
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Buffer.add_char buf (Char.chr (padded_len land 0xff));
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Buffer.add_char buf (Char.chr ((padded_len lsr 8) land 0xff));
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Buffer.add_string buf header;
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for _ = 1 to padded_len - raw_header_len do
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Buffer.add_char buf ' '
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done;
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Buffer.add_char buf '\n';
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Buffer.add_string buf data;
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Buffer.contents buf
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let test_parse_1d_trailing_comma () =
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(* numpy writes 1D shapes as "(5,)" with trailing comma *)
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let header = "{'descr': '|i1', 'fortran_order': False, 'shape': (5,), }" in
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let npy = make_npy_v1_raw header "\x00\x00\x00\x00\x00" in
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match Npy.of_string npy with
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| Error e -> Alcotest.fail e
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| Ok t ->
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Alcotest.(check (array int)) "shape" [|5|] (Npy.shape t)
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let test_parse_scalar_shape () =
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(* scalar: shape () *)
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let header = "{'descr': '<f4', 'fortran_order': False, 'shape': (), }" in
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let bits = Int32.bits_of_float 42.0 in
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let data = String.init 4 (fun i ->
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Char.chr (Int32.to_int (Int32.logand (Int32.shift_right_logical bits (i * 8)) 0xffl))
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) in
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let npy = make_npy_v1_raw header data in
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match Npy.of_string npy with
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| Error e -> Alcotest.fail e
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| Ok t ->
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Alcotest.(check (array int)) "shape" [||] (Npy.shape t);
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(match Npy.data_float32 t with
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| None -> Alcotest.fail "expected float32"
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| Some ba ->
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Alcotest.(check int) "length" 1 (Bigarray.Array1.dim ba))
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let test_wrong_dtype_returns_none () =
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let data = String.init 6 (fun i ->
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Char.chr ([| 1; 255; 127; 128; 0; 42 |].(i))
···
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Alcotest.test_case "float32 header" `Quick test_parse_float32_header;
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Alcotest.test_case "3d shape" `Quick test_parse_3d_shape;
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Alcotest.test_case "bad magic" `Quick test_bad_magic;
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Alcotest.test_case "1d trailing comma" `Quick test_parse_1d_trailing_comma;
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Alcotest.test_case "scalar shape" `Quick test_parse_scalar_shape;
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] );
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( "data",
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[