Reduced diagnostics

WarpX has optional reduced diagnostics, that typically return one value (e.g., particle energy) per timestep.

A simple and quick way to read the data using python is

data = numpy.genfromtxt("filename.txt")

where data is a two dimensional array, data[i][j] gives the data in the ith row and the jth column.

A Python function to read the data is available from module read_raw_data in WarpX/Tools/PostProcessing/:

from read_raw_data import read_reduced_diags
filename = 'EF.txt'
metadata, data = read_reduced_diags( filename )
# list available diagnostics
# Print total field energy on level 0
# Print units for the total field energy on level 0

In addition, for reduced diagnostic type ParticleHistogram, another Python function is available:

from read_raw_data import read_reduced_diags_histogram
filename = 'velocity_distribution.txt'
metadata_dict, data_dict, bin_value, bin_data = read_reduced_diags_histogram( filename )
# 1-D array of the ith bin value
# 2-D array of the jth bin data at the ith time

Another available reduced diagnostic is ParticleHistogram2D. It computes a 2D histogram of particle data with user-specified axes and value functions. The output data is stored in openPMD files gathered in a hist2D/ folder.