@@ -184,13 +184,20 @@ def to_rgba(c, alpha=None):
184184 c : Matplotlib color or ``np.ma.masked``
185185
186186 alpha : float, optional
187- If *alpha* is not ``None``, it forces the alpha value, except if *c* is
188- ``"none"`` (case-insensitive), which always maps to ``(0, 0, 0, 0)``.
187+ If *alpha* is given, force the alpha value of the returned RGBA tuple
188+ to *alpha*.
189+
190+ If None, the alpha value from *c* is used. If *c* does not have an
191+ alpha channel, then alpha defaults to 1.
192+
193+ *alpha* is ignored for the color value ``"none"`` (case-insensitive),
194+ which always maps to ``(0, 0, 0, 0)``.
189195
190196 Returns
191197 -------
192198 tuple
193- Tuple of ``(r, g, b, a)`` scalars.
199+ Tuple of floats ``(r, g, b, a)``, where each channel (red, green, blue,
200+ alpha) can assume values between 0 and 1.
194201 """
195202# Special-case nth color syntax because it should not be cached.
196203if _is_nth_color (c ):
@@ -215,8 +222,12 @@ def _to_rgba_no_colorcycle(c, alpha=None):
215222"""
216223 Convert *c* to an RGBA color, with no support for color-cycle syntax.
217224
218- If *alpha* is not ``None``, it forces the alpha value, except if *c* is
219- ``"none"`` (case-insensitive), which always maps to ``(0, 0, 0, 0)``.
225+ If *alpha* is given, force the alpha value of the returned RGBA tuple
226+ to *alpha*. Otherwise, the alpha value from *c* is used, if it has alpha
227+ information, or defaults to 1.
228+
229+ *alpha* is ignored for the color value ``"none"`` (case-insensitive),
230+ which always maps to ``(0, 0, 0, 0)``.
220231 """
221232orig_c = c
222233if c is np .ma .masked :
@@ -310,16 +321,23 @@ def to_rgba_array(c, alpha=None):
310321 row for each masked value or row in *c*.
311322
312323 alpha : float or sequence of floats, optional
313- If *alpha* is not ``None``, it forces the alpha value, except if *c* is
314- ``"none"`` (case-insensitive), which always maps to ``(0, 0, 0, 0)``.
324+ If *alpha* is given, force the alpha value of the returned RGBA tuple
325+ to *alpha*.
326+
327+ If None, the alpha value from *c* is used. If *c* does not have an
328+ alpha channel, then alpha defaults to 1.
329+
330+ *alpha* is ignored for the color value ``"none"`` (case-insensitive),
331+ which always maps to ``(0, 0, 0, 0)``.
332+
315333 If *alpha* is a sequence and *c* is a single color, *c* will be
316334 repeated to match the length of *alpha*.
317335
318336 Returns
319337 -------
320338 array
321- (n, 4) array of RGBA colors.
322-
339+ (n, 4) array of RGBA colors, where each channel (red, green, blue,
340+ alpha) can assume values between 0 and 1.
323341 """
324342# Special-case inputs that are already arrays, for performance. (If the
325343# array has the wrong kind or shape, raise the error during one-at-a-time