• Kirill Smelkov's avatar
    bigarray: Support resizing in-place · ca064f75
    Kirill Smelkov authored
    In NumPy, ndarray has .resize() but actually it does a whole array
    copy into newly allocated larger segment which makes e.g. appending O(n).
    
    For BigArray, we don't have that internal constraint NumPy has - to
    keep the array itself contiguously _stored_ (compare to contiguously
    _presented_ in memory). So we can have O(1) resize for big arrays.
    
    NOTE having O(1) resize, here is how O(δ) append can be done:
    
        A                               # ZBigArray e.g. of shape   (N, 3)
        n = len(A)                      # lengh of A's major index  =N
        A.resize((n+δ, A.shape[1:]))    # add δ new entries ; now len(A) =N+δ
        A[-δ:] = <new-data>             # set data for last new δ entries
    
    /cc @klaus
    ca064f75
test_basic.py 9.67 KB