Loops

Often you will want to execute the same commands many times with different parameters. This is where python lists and for loops come in handy. This script also shows a simple but crude way of displaying more feedback while operating: it opens the DIS Expose window. We'll see how to display the feedback directly in the script window, plus a better way of formatting exposure commands, in the next lesson.

DISCals script

As always, get permission to use DIS before commanding it.

import TUI.TUIModel

def init(sr):
    """Open the DIS Expose window so the user can see what's going on."""
    tuiModel = TUI.TUIModel.getModel()
    tuiModel.tlSet.makeVisible("None.DIS Expose")

def run(sr):
    """Sample script to take a series of DIS calibration images
    and demonstrate looping through data in Python.
    The exposure times and  # of iterations are short so the demo runs quickly.
    """
    # typeTimeNumList is a list of calibration info
    # each element of the list is a list of:
    # - exposure type
    # - exposure time (sec)
    # - number of exposures
    typeTimeNumList = [
        ["flat", 1, 2],
        ["flat", 5, 2],
        ["bias", 0, 2],
        ["dark", 1, 2],
        ["dark", 5, 2],
    ]
    
    for expType, expTime, numExp in typeTimeNumList:
        if expType == "bias":
            # bias, so cannot specify time
            cmdStr = "%s n=%d name=dis%s" % (expType, numExp, expType)
        else:
            cmdStr = "%s time=%s n=%d name=dis%s" % (expType, expTime, numExp, expType)

        yield sr.waitCmd(
            actor = "disExpose",
            cmdStr = cmdStr,
            abortCmdStr = "abort",
        )

Comments:

• init(sr) runs once, when the script is first loaded. It is often used to add widgets to the script display, but in this case it opens the DIS Expose window to give you feedback as your script runs. We'll use init(sr) to add feedback widgets (eliminating the need to open the DIS Expose window) in the Refinements lesson (NiceDISCals script).
• The TUI model contains information about the internals of TUI, including tlSet, an object containing the main windows in TUI. To learn more about tlSet see Basic Architecture in the Programming manual.
• The for loop is doing two things at once: extracting an item [exposure type, exposure time, number of exposures] from the main data list and "unpacking" that item into three separate variables. That is a common python idiom, equivalent to:

  	for expTypeTimeNum in typeTimeNumList:
  		expType, expTime, numExp = expTypeTimeNum
  	

• The last item in a list may have a comma after it, if desired. I recommend including the comma when each item appears on its own line (as in this example), because it is much easier to add, delete or rearrange items when all lines end with a comma.
• You must place \ at the end of any line being continued unless the line part of code in (), [] or {}. \ is optional (and usually omitted) for continuing lines that are in (), [] or {}. Thus I omitted it in when defining typeTimeNumList.