40 lines
1.4 KiB
BQN
40 lines
1.4 KiB
BQN
⟨SaveNpy,LoadNpy⟩⇐
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lf←@+10
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magicString←(@+147)∾"NUMPY" # "\x93NUMPY"
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To_i16le←{@+256(|∾⌊∘÷˜)𝕩}
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# To_i16le←⟨16,8‿'c'⟩•bit._cast∘≍ # assumes the platform is little-endian
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FloatToBytes←⟨64,8‿'c'⟩•bit._cast
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FormatShape←{'('∾(1↓∾⥊','∾˘•Fmt¨≢𝕩)∾')'}
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BuildHeader←{𝕊𝕩:
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version←1‿0
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# Hypothesis: BQN arrays are C-contiguous
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headerData←"{'descr': '<f8', 'fortran_order': False, 'shape': "∾(FormatShape 𝕩)∾", }"
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padding←' '↑˜64-64|(≠magicString)+2+2+(≠headerData)+1
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! 0=64|(≠magicString)+2+2+(≠padding)+(≠headerData)+1
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headerDataPadded←headerData∾padding∾lf
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magicString∾(@+version)∾(To_i16le ≠headerDataPadded)∾headerDataPadded
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}
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EncodeNpy←BuildHeader∾FloatToBytes∘⥊
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SaveNpy←•file.Bytes⟜EncodeNpy
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ParseHeader←{𝕊𝕩:
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"Not a valid NPY file"! magicString≡(≠magicString)↑𝕩
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version←@-˜(0‿1+≠magicString)⊏𝕩
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headerlen←+´1‿256×@-˜(2‿3+≠magicString)⊏𝕩
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header←(¬∊⟜(' '∾lf))⊸/headerlen↑(4+≠magicString)↓𝕩
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shapestr←(⊐⟜')'↑⊢) (1⊸+∘⊐⟜'('↓⊢) (("shape"⍷header)⊐1)↓header
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shape←•BQN¨','((⊢-˜+`׬)∘=⊔⊢)shapestr
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⟨version,shape,headerlen+2+2+≠magicString⟩
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}
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LoadNpy←{𝕊𝕩:
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bytes←•file.Bytes 𝕩
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version‿shape‿datastart←ParseHeader bytes
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shape⥊⟨8‿'c',64‿'f'⟩•bit._cast datastart↓bytes
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}
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