Arithmetic Widget

The Arithmetic widget allows users to perform basic arithmetic on their spectra that are loaded into Specviz. The arithmetic editor accepts data loaded into the Specviz session and only outputs type specutils.Spectrum1D. This means the editor allows users to perform the same arithmatic operations that are available with specutils.Spectrum1D objects.

Launching Arithmetic Editor

Lets start by loading the arithmetic layer widget located on the tool bar. Upon clicking you will be prompted with the arithmetic dialog

_images/arithmetic-layer.png

From this dialog you can add, edit or remove arithmetic items from the editor. We will start by clicking the New Arithmetic Attribute button located in top left hand corner of the Editor dialog. Upon clicking you will be prompted with the editor dialog

_images/equation_editor.png

Adding Arithmetic

Once the Arithmetic widget is launched, spectra and their components can be added here by typing the names directly surrounded by ‘{}’ or by selecting the spectrum in the dropdown bar and clicking insert. We are going to take the preloaded spectrum (science_spectrum) and create a new spectrum that is double the flux of science_spectrum and call it double science_spectrum.

_images/valid_expression.png

To validate arithmetic, click the OK button located at the bottom right hand corner of the dialog box.

Warning

If the python syntax is invalid, the editor will not allow you to continue! The editor can only return SpecUtils Spectrum1D objects.

Now, there will be a new data item located in the data collection called double science_spectrum.

_images/new_expression.png

To show the result in the plotting window, select the data item by clicking the box next double science_spectrum.

_images/plotted_expression.png

This is a very simple example of the arithmetic you can perform with the SpecViz arithmetic editor. There are more example expressions located at the bottom of the equation editor dialog.