Originally posted by: mcastello

Hi everyone,

I'm currently working on a scheduling project with docplex using the CP optimizer.

I'm using the cp.utils_visu functions to create and display a gantt chart, which works great, but I would like to automatically save thig gantt as a .png file, and I don't see any 'savefig' function in utils_visu.

Here is my code to create and display my gantt chart:

import docplex.cp.utils_visu as visu

if msol and visu.is_visu_enabled():
    visu.timeline('Solution per orders')
    for l in dict_sorted_orders_by_line.keys():
        for order in dict_sorted_orders_by_line[l]:
            visu.sequence(name=str(order))
            for s in SKILLS:
                wt = msol.get_var_solution(wtasks[(order, s)])
                if wt.is_present() and (wt.get_end()-wt.get_start()>0):
                        wtname = compact_name(s.worker , 4)
                        visu.interval(wt,int(l), wtname)
    visu.show()

Do you have any idea how I could do it ?

Thanks for your help.

    import matplotlib.pyplot as plt
    class Show:
        '''Simple context manager to temporarily reroute plt.show().

        This context manager temporarily reroutes the plt.show() function to
        plt.savefig() in order to save the figure to the file specified in the
        constructor rather than displaying it on the screen.'''
        def __init__(self, name):
            self._name = name
            self._orig = None
        def _save(self):
            plt.savefig(self._name)
            if False:
                # Here we could show the figure as well
                self._orig()
        def __enter__(self):
            self._orig = plt.show
            plt.show = lambda: self._save()
            return self
        def __exit__(self, type, value, traceback):
            if self._orig is not None:
                plt.show = self._orig
                self._orig = None​

Then you can do

    with Show('figure.png'):
        visu.show()

to write the image to a file rather than displaying it on screen.

import docplex.cp.utils_visu as visuif msol and visu.is_visu_enabled():    visu.timeline('Solution per orders')    for l in dict_sorted_orders_by_line.keys():        for order in dict_sorted_orders_by_line[l]:            visu.sequence(name=str(order))            for s in SKILLS:                wt = msol.get_var_solution(wtasks[(order, s)])                if wt.is_present() and (wt.get_end()-wt.get_start()>0):                        wtname = compact_name(s.worker , 4)                        visu.interval(wt,int(l), wtname)    visu.show()