6.1.2. Basic usage of PYSPEX

The PYSPEX python module offers a python interface to the SPEX program. This means that you can use SPEX directly either in interactive python mode and in python scripts. In this short tutorial, we assume you are using PYSPEX in interactive mode.

The structure of PYSPEX is chosen such that for many SPEX commands, there is an equivalent class in PYSPEX. These classes contain the functions that copy the functionality of the SPEX command, and if applicable, the classes contain also the output parameters of the SPEX command. This makes it easy to incorporate the SPEX results inside your own program.

In addition to the classes, you can also simply send a SPEX command-line command using the command function (see Section below).

6.1.2.1. Start a PYSPEX session

For this example PYSPEX session in python, we use the interactive mode of python. We simply start python from the Linux command line (making sure that the environment is set using a spexdist script located in the SPEX install directory):

linux:~> source spex/spexdist.sh
linux:~> python
Python 2.7.13
Type "help", "copyright", "credits" or "license" for more information.
>>>

If the PYTHONPATH variable is correctly set, we should now be able to import spex from pyspex:

>>> from pyspex import spex

From here, we can start a SPEX session easily:

>>> s=spex.Session()
 Welcome user to SPEX version 3.05.00

 NEW in this version of SPEX:
11-06-2018 Added Ext_Rate column to new spo files
18-12-2018 SPEX is now using the GPL license

Currently using SPEXACT version 2.07.00. Type `help var calc` for details.
>>>

The s object now contains all the functions and commands that are available to control the SPEX session. For example, we can send SPEX the following command-line commands:

>>> s.command('var calc new')
 Now using SPEXACT version 3.05.00
0
>>> s.com('cie')
 You have defined    1 component.
0
>>> s.calc()
0

With these commands SPEX calculates a CIE spectrum for a temperature of 1 keV.

Although it is possible to call s.command('quit'), the session will be terminated automatically once python is closed or s is reassigned.

Using the command function only does not provide an advantage over the regular command line of SPEX. To really benefit from PYSPEX, you need to use the additional classes which are described in the next sections.

6.1.2.2. The command function

The PYSPEX module contains a general function to send SPEX commands to the SPEX session. This function is especially helpful for SPEX commands that have not been implemented (yet) in PYSPEX. The function returns 0 when the command was successfully executed. If not a non-zero value is returned.

Session.command(comm)[source]

Send a command to SPEX. The command string uses the same syntax as the SPEX commands on the command line.

Parameters

comm (str) – SPEX command.