Popular Python recipes tagged "gradient"

Tkinter frame with gradient (Python)

2017-03-11T03:43:56-08:00

Python recipe 580761 by Miguel Martínez López (canvas, frame, gradient, tkinter). Revision 4.

Frame with linear gradient using PIL.

It's also possible to make the same trick using tkinter PhotoImage.

http://stackoverflow.com/questions/10417524/why-is-photoimage-put-slow

But PIL is more efficient:

https://groups.google.com/forum/#!topic/comp.lang.python/nQ6YO-dTz10

Possible values for orient are: VERTICAL, HORIZONTAL. If orient is "vertical", then width is mandatory. If orient is "horizontal", then height is mandatory. If steps is None, then the gradient is composed of adjacent lines.

One possible practical application of gradient frames are tool bars. Gradient guives a visual clue of when an area starts and when an area finish.

Auto differentiation (Python)

2016-08-07T22:02:10-07:00

Python recipe 580610 by Raymond Hettinger (autodifferentiation, calculus, descent, gradient, math, optimization, vector). Revision 5.

Directly computes derivatives from ordinary Python functions using auto differentiation. The technique directly computes the desired derivatives to full precision without resorting to symbolic math and without making estimates bases on numerical methods.

The module provides a Num class for "dual" numbers that performs both regular floating point math on a value and its derivative at the same time. In addition, the module provides drop-in substitutes for most of the functions in the math module. There are also tools for partial derivatives, directional derivatives, gradients of scalar fields, and the curl and divergence of vector fields.