bugs.py

import numpy as np
from sherpa.astro import ui

# fake up a PHA data set
chans = np.arange(1, 11, dtype=np.int8)
counts = np.ones(chans.size)

# bin width is not 0.1 but something slightly different
ebins = np.linspace(0.1, 1.2, num=chans.size + 1)
elo = ebins[:-1]
ehi = ebins[1:]

dset = ui.DataPHA('test', chans, counts)

# make sure ARF isn't 1 to make sure it's being applied
arf = ui.create_arf(elo, ehi, specresp=0.7 * np.ones(chans.size))

rmf = ui.create_rmf(elo, ehi, e_min=elo, e_max=ehi)

ui.set_data(1, dset)
ui.set_arf(1, arf)
ui.set_rmf(1, rmf)

ui.set_source(ui.const1d.mdl)

# again not 1
mdl.c0 = 8


# Copy the values from the plot structures, since get_xxx_plot
# returns the same object so m1.y == m2.y will not note a difference.
#

d1y = ui.get_data_plot().y.copy()
m1y = ui.get_model_plot().y.copy()
s1y = ui.get_source_plot().y.copy()

d2y = ui.get_data_plot().y.copy()
m2y = ui.get_model_plot().y.copy()
s2y = ui.get_source_plot().y.copy()

def compare_plot(label, p1, p2):
    if np.any(p1 != p2):
        print("{} diffs".format(label))
        print("  {}".format(p1))
        print("  {}".format(p2))

compare_plot('data', d1y, d2y)
compare_plot('model', m1y, m2y)
compare_plot('source', s1y, s2y)

# We expect the model plot to be arf * mdl.c0, so 0.7 * 8 = 5.6
#               source                 mdl.c0, so           8

# Note that 50.909     is   5.6 / 0.11 (ie the bin width of the ARF/RMF)
#           72.7272...        8 / 0.11

gistfile1.txt

% python bugs.py
WARNING: imaging routines will not be available, 
failed to import sherpa.image.ds9_backend due to 
'RuntimeErr: DS9Win unusable: Could not find ds9 on your PATH'
WARNING: failed to import sherpa.astro.xspec; XSPEC models will not be available
model diffs
  [5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6]
  [50.90909091 50.90909091 50.90909091 50.90909091 50.90909091 50.90909091
 50.90909091 50.90909091 50.90909091 50.90909091]
source diffs
  [8. 8. 8. 8. 8. 8. 8. 8. 8. 8.]
  [72.72727273 72.72727273 72.72727273 72.72727273 72.72727273 72.72727273
 72.72727273 72.72727273 72.72727273 72.72727273]