skuschel/postpic: v0.3

2017-09-28

Many improvements in terms of speed and features. Unfortunately some changes are not backwards-compatible to v0.2.3, so you may have to adapt your code to the new interface. For details, see the corresponding section below.

Highlights

• kspace reconstruction and propagation of EM waves.
• postpic.Field properly handles operator overloading and slicing. Slicing can be index based (integers) or referring the actual physical extent on the axis of a Field object (using floats).
• Expression based interface to particle properties (see below)

Incompatible adjustments to last version

• New dependency: Postpic requires the numexpr package to be installed now.
• Expression based interface of for particles: If ms is a postpic.MultiSpecies object, then the call ms.X() has been deprecated. Use ms('x') instead. This new particle interface can handle expressions that the numexpr package understands. Also ms('sqrt(x**2 + gamma - id)') is valid. This interface is easier to use, has better functionality and is faster due to numexpr. The list of known per particle scalars and their definitions is available at postpic.particle_scalars. In addition all constants of scipy.constants.* can be used. In case you find particle scalar that you use regularly which is not in the list, please open an issue and let us know!
• The postpic.Field class now behaves more like an numpy.ndarray which means that almost all functions return a new field object instead of modifying the current. This change affects the following functions: half_resolution, autoreduce, cutout, mean.

Other improvements and new features

• postpic.helper.kspace can reconstruct the correct k-space from three EM fields provided to distinguish between forward and backward propagating waves (thanks to @Ablinne)
• postpic.helper.kspace_propagate will turn the phases in k-space to propagate the EM-wave.
• List of new functions in postpic from postpic.helper (thanks to @Ablinne): kspace_epoch_like, kspace, kspace_propagate.
• Field.fft function for fft optimized with pyfftw (thanks to @Ablinne).
• Field.__getitem__ to slice a Field object. If integers are provided, it will interpret them as gridpoints. If float are provided they are interpreted as the physical region of the data and slice along the corresponding axis positions (thanks to @Ablinne).
• Field class has been massively impoved (thanks to @Ablinne): The operator overloading is now properly implemented and thanks to __array__ method, it can be interpreted by numpy as an ndarray whenever neccessary.
• List of new functions of the Field class (thanks to @Ablinne): meshgrid, conj, replace_data, pad, transform, squeeze, integrate, fft, shift_grid_by, __getitem__, __setitem__.
• List of new properties of the Field class (thanks to @Ablinne): matrix, real, imag, angle.
• Many performance optimizations using pyfftw library (optional) or numexpr (now required by postpic) or by avoiding in memory data copying.
• Lots of fixes