Femzip

Documentation of the Femzip module. The D3plot reader uses this module to access femzip file data through the femzip API. It also allows to decompress files directly or use some additional utility functions such as a femzip file check if desired.

Example

>>> from lasso.femzip import FemzipAPI
>>> from ctypes import *
>>> filepath = "path/to/d3plot.fz"

>>> # Initialize API
>>> api = FemzipAPI()

Here we check if we can use the extended FEMZIP-API. The extended FEMZIP-API allows reading selected arrays, but reqires a license with the feature "FEMUNZIPLIB-DYNA", which can be attained from SIDACT or femzip distributors.

>>> api.has_femunziplib_license()
True

Check if a file is femzipped:

>>> # check if file is femzipped
>>> api.is_sidact_file(filepath)
True

Check the file and library version. This is usually not neccessary.

>>> api.is_femunzip_version_ok(filepath)
True

It's efficient to get the memory demand for arrays beforehand and hand this memory info to other functions. It is often not mandatory though and a mere speedup.

>>> # read memory demand info first
>>> buffer_info = api.get_buffer_info(filepath)
>>> # buffer info is a c struct, but we can print it
>>> api.struct_to_dict(buffer_info)
{'n_timesteps': 12, 'timesteps': <lasso.femzip.femzip_api.LP_c_float object at 0x0000028A8F6B21C0>, 'size_geometry': 537125, 'size_state': 1462902, 'size_displacement': 147716, 'size_activity': 47385, 'size_post': 1266356, 'size_titles': 1448}
>>> for i_timestep in range(buffer_info.n_timesteps):
>>>     print(buffer_info.timesteps[i_timestep])
0.0
0.9998100399971008
1.9998900890350342
2.9999701976776123
3.9997801780700684

Here we read the geometry buffer. The file is kept open so that we can read states afterwards.

>>> mview = api.read_geometry(filepath, buffer_info, close_file=False)

Femzip can handle only one file per process. In case of issues close the current file (shown later). We can check the API status as follows

>>> print(api.struct_to_dict(api.get_femzip_status()))
{'is_file_open': 1, 'is_geometry_read': 1, 'is_states_open': 0, 'i_timestep_state': -1, 'i_timestep_activity': -1}

Get the memory of a single state. Must start at 0. Femzip does not allow reading arbitrary states inbetween.

>>> mview = api.read_single_state(i_timestep=0, buffer_info=buffer_info)

It is also possible to read the state memory directly into an already allocated buffer.

>>> BufferType = c_float * (buffer_info.size_state)
>>> mview = memoryview(BufferType())
>>> api.read_single_state(1, buffer_info=buffer_info, state_buffer=mview)

Let's close the file manually. This ensures that femzip resets its internal state.

>>> api.close_current_file()