mobile=[['apple','ios','100','10'],['pear','android','200','20'],['apple','ios','500','50'],['pear','android','600','60']] mobiledict={} for elem in mobile: key=(elem[0],elem[1]) if key in mobiledict: mobiledict[key][0]+=int(elem[2]) mobiledict[key][1]+=int(elem[3]) else: mobiledict[key]=[int(elem[2]),int(elem[3])] print(mobiledict)