To be used with the i3 window manager (and i3-py). Takes a command 'save' or 'restore'. When 'save' is used it will store the monitor that each workspace is assigned to. When 'restore' is used it will restore those workspaces to the monitor that it was

i3plug.py

import os
import i3
import sys
import pickle

def showHelp():
    print(sys.argv[0] + " <save|restore>")

def get_visible_workspace():
    for workspace in i3.get_workspaces():
        if workspace['visible']:
            return workspace['name']

if __name__ == '__main__':
    if len(sys.argv) < 2:
        showHelp()
        sys.exit(1)

    if sys.argv[1] == 'save':
        print("Storing...")
        workspace_mapping = {}
        for workspace in i3.get_workspaces():
            workspace_mapping[workspace['name']] = workspace['output']
        pickle.dump(workspace_mapping, open("%s/.i3/workspace_mapping" % os.path.expanduser("~"), "wb"))
    elif sys.argv[1] == 'restore':
        print("Restoring")
        try:
            workspace_mapping = pickle.load(open("%s/.i3/workspace_mapping" % os.path.expanduser("~"), "rb"))
        except Exception:
            print("Can't find existing mappings...")
            sys.exit(1)
        current_workspace = get_visible_workspace()
        for workspace in i3.get_workspaces():
            if workspace['name'] in workspace_mapping:
                i3.msg('command', 'workspace %s' % workspace['name'])
                i3.msg('command', 'move workspace to output %s' % workspace_mapping[workspace['name']])
        i3.msg('command', 'workspace %s' % current_workspace)
    else:
        showHelp()
        sys.exit(1)