# Working with a split-screen brain¶

The split-screen view can be activated by using the argument hemi='split'. Using this option will put views of the left hemisphere in consecutive vertical frames on the left, and views of the right hemisphere in consecutive vertical frames on the right. For example, running the following:

brain = Brain('fsaverage', 'split', 'inflated', views=['lat', 'med'])


Will produce a window with two columns (hemispheres) and two rows (the lateral and medial views, respectively), shown below.

Data can be added to either hemisphere using the same functions that are normally used, e.g. add_data, add_overlay, add_morphometry. The objects are automatically shown on all views of the brain. When calling these functions, the hemi keyword argument can be set to hemi='lh' or hemi='rh' to specify the hemisphere to plot to. In some instances (e.g., add_morphometry), if no keyword argument is provided, PySurfer will attempt to load data or both hemispheres automtically.
Note that the show_view method accepts arguments for the row and col values, which allow the user to control which Brain panel gets the updated view.
The multi-view support is available thanks to the capabilities of the TraitsUI framework. However, due to some limitations in the implementation of TraitsUI, there is no guarantee that a set of scripted commands will result in a painted window when the user may think it will. For example, making a series of calls to brain.add_label() followed by brain.save_image('out.png') may result in some or all of the labels being absent from the saved out.png. While we have implemented some workarounds to help prevent this occurrance, we cannot guarantee it will work. Thus we recommend that for critical non-interactive plotting (e.g., if scripting figure generation for a paper) only a single view is used with hemi set to 'lh', 'rh', or 'both'. This will use a single, pure Mayavi window, thereby bypassing TraisUI entirely – this helps guarantee that drawing commands result in updated visual display.