Optimization: Replace arr.flat[0].decode() with arr.item().decode() for efficient scalar extraction

[SaFE-APIOpt]

nappy/nappy/utils/common_utils.py

Line 270 in 109b542

return arr.flat[0].decode()

Hi, I’d like to suggest a small improvement to the following code:

elif arr.dtype.type is np.bytes_:
    return arr.flat[0].decode()

This can be optimized and simplified as:

elif arr.dtype.type is np.bytes_:
    return arr.item(0).decode()

When the array is known to contain a single byte string, arr.item() is the most efficient and appropriate method to extract that value. Unlike arr.flat[0], which internally constructs a flatiter object and performs Python-level indexing, item() directly accesses the first (and only) scalar element via a low-level C API call, avoiding unnecessary indirection. This improves both performance and readability, especially in code paths that are frequently executed. The use of item(0) also more clearly conveys the intent of accessing a single scalar, aligning better with the semantic purpose of the check.