diff options
Diffstat (limited to 'numpy/lib/twodim_base.py')
| -rw-r--r-- | numpy/lib/twodim_base.py | 116 |
1 files changed, 97 insertions, 19 deletions
diff --git a/numpy/lib/twodim_base.py b/numpy/lib/twodim_base.py index 2b4cbdfbb..83c028061 100644 --- a/numpy/lib/twodim_base.py +++ b/numpy/lib/twodim_base.py @@ -5,12 +5,13 @@ import functools from numpy.core.numeric import ( asanyarray, arange, zeros, greater_equal, multiply, ones, - asarray, where, int8, int16, int32, int64, empty, promote_types, diagonal, - nonzero + asarray, where, int8, int16, int32, int64, intp, empty, promote_types, + diagonal, nonzero, indices ) from numpy.core.overrides import set_array_function_like_doc, set_module from numpy.core import overrides from numpy.core import iinfo +from numpy.lib.stride_tricks import broadcast_to __all__ = [ @@ -46,10 +47,11 @@ def _flip_dispatcher(m): @array_function_dispatch(_flip_dispatcher) def fliplr(m): """ - Flip array in the left/right direction. + Reverse the order of elements along axis 1 (left/right). - Flip the entries in each row in the left/right direction. - Columns are preserved, but appear in a different order than before. + For a 2-D array, this flips the entries in each row in the left/right + direction. Columns are preserved, but appear in a different order than + before. Parameters ---------- @@ -65,11 +67,13 @@ def fliplr(m): See Also -------- flipud : Flip array in the up/down direction. + flip : Flip array in one or more dimesions. rot90 : Rotate array counterclockwise. Notes ----- - Equivalent to m[:,::-1]. Requires the array to be at least 2-D. + Equivalent to ``m[:,::-1]`` or ``np.flip(m, axis=1)``. + Requires the array to be at least 2-D. Examples -------- @@ -97,10 +101,10 @@ def fliplr(m): @array_function_dispatch(_flip_dispatcher) def flipud(m): """ - Flip array in the up/down direction. + Reverse the order of elements along axis 0 (up/down). - Flip the entries in each column in the up/down direction. - Rows are preserved, but appear in a different order than before. + For a 2-D array, this flips the entries in each column in the up/down + direction. Rows are preserved, but appear in a different order than before. Parameters ---------- @@ -116,12 +120,13 @@ def flipud(m): See Also -------- fliplr : Flip array in the left/right direction. + flip : Flip array in one or more dimesions. rot90 : Rotate array counterclockwise. Notes ----- - Equivalent to ``m[::-1,...]``. - Does not require the array to be two-dimensional. + Equivalent to ``m[::-1, ...]`` or ``np.flip(m, axis=0)``. + Requires the array to be at least 1-D. Examples -------- @@ -347,10 +352,10 @@ def diagflat(v, k=0): n = s + abs(k) res = zeros((n, n), v.dtype) if (k >= 0): - i = arange(0, n-k) + i = arange(0, n-k, dtype=intp) fi = i+k+i*n else: - i = arange(0, n+k) + i = arange(0, n+k, dtype=intp) fi = i+(i-k)*n res.flat[fi] = v if not wrap: @@ -434,10 +439,12 @@ def tril(m, k=0): Lower triangle of an array. Return a copy of an array with elements above the `k`-th diagonal zeroed. + For arrays with ``ndim`` exceeding 2, `tril` will apply to the final two + axes. Parameters ---------- - m : array_like, shape (M, N) + m : array_like, shape (..., M, N) Input array. k : int, optional Diagonal above which to zero elements. `k = 0` (the default) is the @@ -445,7 +452,7 @@ def tril(m, k=0): Returns ------- - tril : ndarray, shape (M, N) + tril : ndarray, shape (..., M, N) Lower triangle of `m`, of same shape and data-type as `m`. See Also @@ -460,6 +467,20 @@ def tril(m, k=0): [ 7, 8, 0], [10, 11, 12]]) + >>> np.tril(np.arange(3*4*5).reshape(3, 4, 5)) + array([[[ 0, 0, 0, 0, 0], + [ 5, 6, 0, 0, 0], + [10, 11, 12, 0, 0], + [15, 16, 17, 18, 0]], + [[20, 0, 0, 0, 0], + [25, 26, 0, 0, 0], + [30, 31, 32, 0, 0], + [35, 36, 37, 38, 0]], + [[40, 0, 0, 0, 0], + [45, 46, 0, 0, 0], + [50, 51, 52, 0, 0], + [55, 56, 57, 58, 0]]]) + """ m = asanyarray(m) mask = tri(*m.shape[-2:], k=k, dtype=bool) @@ -473,7 +494,8 @@ def triu(m, k=0): Upper triangle of an array. Return a copy of an array with the elements below the `k`-th diagonal - zeroed. + zeroed. For arrays with ``ndim`` exceeding 2, `triu` will apply to the final + two axes. Please refer to the documentation for `tril` for further details. @@ -489,6 +511,20 @@ def triu(m, k=0): [ 0, 8, 9], [ 0, 0, 12]]) + >>> np.triu(np.arange(3*4*5).reshape(3, 4, 5)) + array([[[ 0, 1, 2, 3, 4], + [ 0, 6, 7, 8, 9], + [ 0, 0, 12, 13, 14], + [ 0, 0, 0, 18, 19]], + [[20, 21, 22, 23, 24], + [ 0, 26, 27, 28, 29], + [ 0, 0, 32, 33, 34], + [ 0, 0, 0, 38, 39]], + [[40, 41, 42, 43, 44], + [ 0, 46, 47, 48, 49], + [ 0, 0, 52, 53, 54], + [ 0, 0, 0, 58, 59]]]) + """ m = asanyarray(m) mask = tri(*m.shape[-2:], k=k-1, dtype=bool) @@ -700,7 +736,9 @@ def histogram2d(x, y, bins=10, range=None, normed=None, weights=None, >>> x = np.random.normal(2, 1, 100) >>> y = np.random.normal(1, 1, 100) >>> H, xedges, yedges = np.histogram2d(x, y, bins=(xedges, yedges)) - >>> H = H.T # Let each row list bins with common y range. + >>> # Histogram does not follow Cartesian convention (see Notes), + >>> # therefore transpose H for visualization purposes. + >>> H = H.T :func:`imshow <matplotlib.pyplot.imshow>` can only display square bins: @@ -730,6 +768,40 @@ def histogram2d(x, y, bins=10, range=None, normed=None, weights=None, >>> ax.images.append(im) >>> plt.show() + It is also possible to construct a 2-D histogram without specifying bin + edges: + + >>> # Generate non-symmetric test data + >>> n = 10000 + >>> x = np.linspace(1, 100, n) + >>> y = 2*np.log(x) + np.random.rand(n) - 0.5 + >>> # Compute 2d histogram. Note the order of x/y and xedges/yedges + >>> H, yedges, xedges = np.histogram2d(y, x, bins=20) + + Now we can plot the histogram using + :func:`pcolormesh <matplotlib.pyplot.pcolormesh>`, and a + :func:`hexbin <matplotlib.pyplot.hexbin>` for comparison. + + >>> # Plot histogram using pcolormesh + >>> fig, (ax1, ax2) = plt.subplots(ncols=2, sharey=True) + >>> ax1.pcolormesh(xedges, yedges, H, cmap='rainbow') + >>> ax1.plot(x, 2*np.log(x), 'k-') + >>> ax1.set_xlim(x.min(), x.max()) + >>> ax1.set_ylim(y.min(), y.max()) + >>> ax1.set_xlabel('x') + >>> ax1.set_ylabel('y') + >>> ax1.set_title('histogram2d') + >>> ax1.grid() + + >>> # Create hexbin plot for comparison + >>> ax2.hexbin(x, y, gridsize=20, cmap='rainbow') + >>> ax2.plot(x, 2*np.log(x), 'k-') + >>> ax2.set_title('hexbin') + >>> ax2.set_xlim(x.min(), x.max()) + >>> ax2.set_xlabel('x') + >>> ax2.grid() + + >>> plt.show() """ from numpy import histogramdd @@ -894,7 +966,10 @@ def tril_indices(n, k=0, m=None): [-10, -10, -10, -10]]) """ - return nonzero(tri(n, m, k=k, dtype=bool)) + tri_ = tri(n, m, k=k, dtype=bool) + + return tuple(broadcast_to(inds, tri_.shape)[tri_] + for inds in indices(tri_.shape, sparse=True)) def _trilu_indices_form_dispatcher(arr, k=None): @@ -1010,7 +1085,10 @@ def triu_indices(n, k=0, m=None): [ 12, 13, 14, -1]]) """ - return nonzero(~tri(n, m, k=k-1, dtype=bool)) + tri_ = ~tri(n, m, k=k - 1, dtype=bool) + + return tuple(broadcast_to(inds, tri_.shape)[tri_] + for inds in indices(tri_.shape, sparse=True)) @array_function_dispatch(_trilu_indices_form_dispatcher) |