cmb-s4 / s4sim

Simulation tools

CMB-S4 Package s4sim

This package contains simulation tools that will be used for modeling of instrument properties useful for trade studies and forecasts.

Package Installation

This package uses setuptools for package installation. You can use the setup.py directly for installation or use pip. Using pip makes it possible to uninstall the package cleanly. Installation to a specific location can be done with:

%>  pip3 install . --prefix=/some/place

OR

%>  python3 setup.py install --prefix /some/place

If you specify a --prefix option, then that location should already be in your PATH / PYTHONPATH environment. For example, you must have previously set up your environment with:

%>  export PATH="/some/place/bin:${PATH}"
%>  export PYTHONPATH="/some/place/lib/python3.x/site-packages:${PYTHONPATH}"

Where 3.x is the actual python version you are using. If you do not specify a --prefix option, the package will be installed to your python installation prefix. If you are using a virtualenv or a conda environment for your development work (always a good idea!) then it is safe to leave out the --prefix option and install the package into your environment.

If you have used pip to do the installation, then you can uninstall with:

%>  pip3 uninstall s4sim

If you want to be able to edit the source and have those changes show up in your environment without re-installing, then you can use the package in develop / editable mode. This is done slightly differently depending on whether you use setup.py directly or pip:

%>  pip3 install -e . --prefix=/some/place

OR

%>  python3 setup.py develop --prefix /some/place

These commands will fail unless the prefix is in your PYTHONPATH.

Running Unit Tests

The unit tests are contained within the package itself. This has the benefit that we are certain to be running the tests on the installed package, rather than running tests against a locally built (and perhaps different) version of the package. After installing the package (or using the develop / editable option), run tests with:

%> python3 -c 'import s4sim.tests; s4sim.tests.run()'

Package Development

When developing the code, you should install (e.g. with pip or conda) the "black" python formatting package. When making changes to the source, and before committing, run the format_source.sh script in the top directory. This applies formatting rules to all the source files.

See DocDB XXXX for relevant coding guidelines.

Hardware Configuration Package

The baseline hardware configuration is stored in the s4sim.hardware module and is called via the get_example function.

• config.py defines the basic structure of the experiment including the detector and readout properties, the wafer properties, the tube properties, and the telescope properties

• sim.py defines the wafer layout and distribution of wafers in each optics tube

The reference instrument model is available in this spreadsheet on Google Docs

Example usage

The reference design is included in the config.py module and is generated by calling the get_example() function:

from s4sim.hardware.config import get_example
hardware = get_example()

hardware has a data attribute which is a dictionary that contains all the instrument parameters, for example you can access the noise and bandpass properties:

> hardware.data["bands"]["HFS1"]
OrderedDict([('center', 220.0),
             ('low', 195.8),
             ('high', 244.2),
             ('bandpass', ''),
             ('NET', 747.0),
             ('fknee', 50.0),
             ('fmin', 0.01),
             ('alpha', 3.5),
             ('A', 0.3),
             ('C', 0.58)])

or the beam:

> hardware.data["telescopes"]["SAT5"]["fwhm"]
OrderedDict([('LFS1', 72.8),
             ('LFS2', 54.8),
             ('MFLS1', 25.5),
             ('MFLS2', 15.1),
             ('MFHS1', 22.7),
             ('MFHS2', 14.2),
             ('HFS1', 13.0),
             ('HFS2', 10.0)])

It also includes facilities to dump and load the instrument configuration from a TOML file, see the dump and load methods. You can also output to a TOML file by running 's4_hardware_sim.py' from the 's4sim.scripts' package. This TOML file can be trimmed with 's4_hardware_trim.py' and visualized with 's4_hardware_plot.py".