diff --git a/numpy/numba/README.md b/numpy/numba/README.md index 2fed16d..507e15c 100644 --- a/numpy/numba/README.md +++ b/numpy/numba/README.md @@ -20,25 +20,54 @@ pip install numba ## [Numba basic types](https://numba.pydata.org/numba-doc/dev/reference/types.html) +For the example that will show you the options of optimization we need to understand the numba naming schema. + +### Numbers + +For the function signatures we need to be able to translate the usual np.dtype into numpy.types. + +For doing so we just replace **np.** by **numba.types.** . |Type name(s)| Shorthand| Comments| |---|---|---| -|boolean |b1| represented as a byte| -|uint8, byte |u1| 8-bit unsigned byte| -|uint16 |u2| 16-bit unsigned integer| -|uint32 |u4| 32-bit unsigned integer| -|uint64 |u8| 64-bit unsigned integer| -|int8, char |i1| 8-bit signed byte| -|int16 |i2| 16-bit signed integer| -|int32 |i4| 32-bit signed integer| -|int64 |i8| 64-bit signed integer| -|intc |–| C int-sized integer| -|uintc |–| C int-sized unsigned integer| -|intp |–| pointer-sized integer| -|uintp |–| pointer-sized unsigned integer| -|float32| f4| single-precision floating-point number| -|float64, double| f8| double-precision floating-point number| -|complex64| c8| single-precision complex number| -|complex128| c16| double-precision complex number| +|numba.types.boolean |b1| represented as a byte| +|numba.types.uint8, byte |u1| 8-bit unsigned byte| +|numba.types.uint16 |u2| 16-bit unsigned integer| +|numba.types.uint32 |u4| 32-bit unsigned integer| +|numba.types.uint64 |u8| 64-bit unsigned integer| +|numba.types.int8, char |i1| 8-bit signed byte| +|numba.types.int16 |i2| 16-bit signed integer| +|numba.types.int32 |i4| 32-bit signed integer| +|numba.types.int64 |i8| 64-bit signed integer| +|numba.types.intc |–| C int-sized integer| +|numba.types.uintc |–| C int-sized unsigned integer| +|numba.types.intp |–| pointer-sized integer| +|numba.types.uintp |–| pointer-sized unsigned integer| +|numba.types.float32| f4| single-precision floating-point number| +|numba.types.float64, double| f8| double-precision floating-point number| +|numba.types.complex64| c8| single-precision complex number| +|numba.types.complex128| c16| double-precision complex number| +### Arrays + +If we have arrays in the function signature, which is a very likely senario, we might want to give as much information to numpy as possible about the numpy.ndarray. In some cases it is very benificial to make a np.ndarray an array with C memory layout and tell numba about it. + +We can use the numpy function **numpy.ascontiguousarray for** converting a numpy array into a C memory layout. + +We can also check a numpy array, let's call it X, if it is already in the C memory layout. This is done by looking at **X.flags['C_CONTIGUOUS']**. + +Some example for array signatures are: + +||| +|---|---| +|numba.types.float32[:]| 1d array of float32 with no particular memory layout| +|numba.types.float32[:,:]| 2d array of float32 with no particular memory layout| +|numba.types.float32[:,:,:]| 3d array of float32 with no particular memory layout| +|numba.types.float32[::1]| 1d array of float32 with C memory layout| +|numba.types.float32[:,::1]| 2d array of float32 with C memory layout| +|numba.types.float32[:,:,::1]| 3d array of float32 with C memory layout| +|numba.types.float32[::1,:]| 2d array of float32 with Fortran memory layout| +|numba.types.float32[::1,:,:]| 3d array of float32 with Fortran memory layout| + +## An example (up to 437x faster)