Using !-string and #-string commands

!-strings are for setting simulation parameters

!-strings are a convenient way of accessing multiple layers of a nested dictionary structure with a single string using the format:

"!<ALIAS>.<sub-dict>...<sub-dict>.<param>"

Any level of the nested dictionary can be reached by truncating the keyword.

Note: !-strings only work on ``UserCommands`` objects

Below is an example of how to use !-strings, using the example optical train.

import scopesim as sim
opt = sim.load_example_optical_train()

opt.cmds["!ATMO"]

opt.cmds["!ATMO.background"]

opt.cmds["!ATMO.background.filter_name"]

#-strings are for accessing Effect object parameters

Similar to !-strings, #-strings allow us to get at the preset values inside the Effect-objects of the optical system. #-strings allow us to pring the contents of an effect’s meta dictionary.

Note: !-strings only work on ``OpticalTrain`` objects

Here, we’re again using the example optical train defined above. First let’s list the effects:

opt.effects

We list the meta dictionary contents by using the string format

"#<effect-name>."

Note: The ``.`` at the end is important, otherwise the optical train will look for a non-existant effect named ``#<effect-name>``

opt["#exposure_action."]

We print a specific meta parameter by adding it after the .

opt["#exposure_action.ndit"]

Notice that the value of this dictionary entry is itself a !-string. We can resolve this by adding a ! to the end of the string, to force it to get the actual value from opt.cmds:

opt["#exposure_action.ndit!"]