Spectra
Visually explore series of spectra with no spatial information.
- Inputs
- Data
input dataset
- Data Subset
subset of the data
- Outputs
- Selection
selected spectra
The Spectra widget allows visual exploration of multiple spectra. To output some spectra, select them by clicking. For multiple selection, hold the modifier key (Ctrl or Cmd) or use line selection (see the menu). Selected spectra will appear dashed.

Open the plot options menu
A spectrum
The X and Y position of the cursor
The legend (appears only is spectra are colored)
Navigation
Click + drag: move the plot
Right-click: zoom to fit
Right-click + drag: zoom with mouse movement
Scroll: zoom X axis
Scroll + modifier: zoom Y axis
Plot options
Resample curves (R): resample the displayed a subset (only a subset is displayed for performance)
Resampling reset (Mod + R): resample to the default view
Zoom in (Z): zoom to a region (selected afterwards)
Zoom to fit (Backspace): return to the original plot
Rescale Y to fit (D): rescale the Y axis to fit the screen (useful if zoomed-in)
Show averages (A): show the average and standard deviation (per group)
Show grid (G): show the grid for a better inspection of the plot
Invert X (X): invert the order of the X axis
Select (line) (S): select the spectra touching a line (draw a line with a mouse)
Save graph (Mod + S): export the visualization to an imags
Define view range: define a specific range to display
Color by: a categorical feature for coloring
Title, X-axis, Y-axis: annotate the plot
Example
The Spectra widget is used to visualize spectral data. X axis normally shows wavenumbers, while the Y axis shows the absorbance. We will plot the Liver spectroscopy data from the Datasets widget as an example.
We have used Color by option to display the type of each spectrum. Or you can also press ‘C’ and the plot will show colors.
Now, let’s say I am interested in those spectra, that are quite separated from the rest at wavenumber around 1027. I will press ‘S’, click once where I want my selection to start and once where I want it to end. This will select the spectra under the line I have dragged.
I can observe the selection in another Spectra widget or use it for further analysis.
