diff options
Diffstat (limited to 'numpy/lib/arraysetops.py')
| -rw-r--r-- | numpy/lib/arraysetops.py | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/numpy/lib/arraysetops.py b/numpy/lib/arraysetops.py index 22687b941..6a2ad004c 100644 --- a/numpy/lib/arraysetops.py +++ b/numpy/lib/arraysetops.py @@ -206,6 +206,7 @@ def unique(ar, return_index=False, return_inverse=False, -------- numpy.lib.arraysetops : Module with a number of other functions for performing set operations on arrays. + repeat : Repeat elements of an array. Notes ----- @@ -244,7 +245,7 @@ def unique(ar, return_index=False, return_inverse=False, >>> a[indices] array(['a', 'b', 'c'], dtype='<U1') - Reconstruct the input array from the unique values: + Reconstruct the input array from the unique values and inverse: >>> a = np.array([1, 2, 6, 4, 2, 3, 2]) >>> u, indices = np.unique(a, return_inverse=True) @@ -255,6 +256,17 @@ def unique(ar, return_index=False, return_inverse=False, >>> u[indices] array([1, 2, 6, 4, 2, 3, 2]) + Reconstruct the input values from the unique values and counts: + + >>> a = np.array([1, 2, 6, 4, 2, 3, 2]) + >>> values, counts = np.unique(a, return_counts=True) + >>> values + array([1, 2, 3, 4, 6]) + >>> counts + array([1, 3, 1, 1, 1]) + >>> np.repeat(values, counts) + array([1, 2, 2, 2, 3, 4, 6]) # original order not preserved + """ ar = np.asanyarray(ar) if axis is None: @@ -266,7 +278,7 @@ def unique(ar, return_index=False, return_inverse=False, ar = np.moveaxis(ar, axis, 0) except np.AxisError: # this removes the "axis1" or "axis2" prefix from the error message - raise np.AxisError(axis, ar.ndim) + raise np.AxisError(axis, ar.ndim) from None # Must reshape to a contiguous 2D array for this to work... orig_shape, orig_dtype = ar.shape, ar.dtype @@ -288,10 +300,10 @@ def unique(ar, return_index=False, return_inverse=False, # array with shape `(len(ar),)`. Because `dtype` in this case has # itemsize 0, the total size of the result is still 0 bytes. consolidated = np.empty(len(ar), dtype=dtype) - except TypeError: + except TypeError as e: # There's no good way to do this for object arrays, etc... msg = 'The axis argument to unique is not supported for dtype {dt}' - raise TypeError(msg.format(dt=ar.dtype)) + raise TypeError(msg.format(dt=ar.dtype)) from e def reshape_uniq(uniq): n = len(uniq) @@ -357,7 +369,9 @@ def intersect1d(ar1, ar2, assume_unique=False, return_indices=False): Input arrays. Will be flattened if not already 1D. assume_unique : bool If True, the input arrays are both assumed to be unique, which - can speed up the calculation. Default is False. + can speed up the calculation. If True but ``ar1`` or ``ar2`` are not + unique, incorrect results and out-of-bounds indices could result. + Default is False. return_indices : bool If True, the indices which correspond to the intersection of the two arrays are returned. The first instance of a value is used if there are |