Getting started

The standard HEAsoft build makes a Python 3 module based on the HEASP C++ classes described in the next chapter. The standard HEAsoft initialization script adds the location of the HEASP Python module to PYTHONPATH. To load the module use

UNIX> python3
>>>from heasp import *

If this produces name conflicts then loading the module by

UNIX> python3
>>>import heasp

requires heasp. in front of all commands. Since heasp C++ vectors are mapped to numpy arrays it is also a good idea to load the numpy module by

>>>from numpy import *

To set up an HEASP object first give a simple command such as

>>>sp = pha()

for a spectrum. This can then be read in and information about it displayed by

>>>sp.read("file1.pha")
>>>sp.disp()

Alternatively, the object can be defined directly from a file by

>>>sp = pha("file1.pha")
>>>sp.disp()

Individual components of the object can be accessed by get methods. For instance:

>>>first = sp.getFirstChannel()

will place the first channel number in the variable first. There are corresponding set methods. For instance:

>>>sp.setFirstChannel(0)

The components of each class are given in the appropriate chapter describing the C++ interface.

Components which are arrays can be loaded into numpy arrays. For instance:

>>>counts = sp.getPha()

Alternatively, a single element can be accessed:

>>>sp.getPhaElement(5)

Going the other way, a single element of the current contents of the PHA column can be replaced by e.g.:

>>>sp.setPhaElement(5,0.4)

and the entire array using e.g.:

sp.setPha(array([0.1,0.2,0.3,0.4,0.5]))

Setting an individual element does not resize the array but setting the entire array does.