Page History
...
| Warning | ||
|---|---|---|
| ||
The Pandeia Engine API may change at any time. The following information and examples are for Pandeia Engine 2.0.x only, and are not guaranteed to be accurate or functional for previous or future releases. Updates (and information about planned pending API changes) can be found on the Pandeia Engine News page. |
...
Engine inputs take the form of a heirarchical Python dictionary describing, in different sections, the instrument setup, the scene with definitions of all sources within it, and the flux extraction strategy.
Such input dictionaries are available in JWST Webapp download files (as a JSON-formatted file named input.json, suitable for reading in with the built-in Python 'json' module), or default versions can be created with the function build_default_calc() and then edited (this is the only option for Roman Space Telescope calculations)
| Warning | ||
|---|---|---|
| ||
The Pandeia Engine expects a specific hierarchical format, but does not generally validate the format. It may silently replace missing or misplaced information with defaults, and it generally will not warn about keys in the wrong place. |
Create a default calculation
| Code Block | ||||||
|---|---|---|---|---|---|---|
| ||||||
from pandeia.engine import calc_utils from pandeia.engine import perform_calculation resultcalculation = calc_utils.build_default_calc("jwst","nircam","sw_imaging") results = perform_calculation.perform_calculation(calculation) |
where "calculation" is a hierarchical input dictionary describing a scene of sources, an instrument setup, and an extraction strategy, and "result" is a hierarchical output dictionary.
...
The command above produces the NIRCam SW Imaging calculation below, and then runs it through the engine. "results" will be a dictionary, defined in the Output API documentation
| Warning | ||
|---|---|---|
| ||
In the event that there is a typo in the mode name ("sw_imaging", above), the function will substitute the default mode for that instrument. |
Load a calculation from the JWST Webapp
Calculation downloads from the JWST Webapp contain the engine inputs in a JSON-formatted text file called input.json.
| Code Block | ||||
|---|---|---|---|---|
| ||||
import json from pandeia.engine import calc_utils calculation = calc_utils.build_default_calc("jwst","nircam","sw_imaging") |
The command above produces the NIRCam SW Imaging calculation below.
...
| title | API Default |
|---|
perform_calculation
with open("input.json") as infile:
calculation = json.load(infile)
results = perform_calculation.perform_calculation(calculation) |
The command above reads a file called "input.json" in the current directory, loads it into a Python dictionary, and runs it through the engine. "results" will be a dictionary, defined in the Output API documentation. Results should match the JWST Webapp
...
.
Full API
The full API documentation, with all possible options and combinations for any instrument, can be found in this link.
...
The following calculation defines a JWST NIRCam observation in SW Imaging mode using the full subarray and rapid readout pattern and f070w filter, for a flat-spectrum (in fnu) point source normalized to 0.001 mJy, intended to be observed with a 0.2" aperture. Note that it specifies a background precomputed for a specific date and celestial locationthe JWST minzodi benchmark position; actual user-configured backgrounds are available in the JWST web ETC Webapp (and can be downloaded from there)
...
