In a medium pot, place cranberries, sugar, water and pineapple juice, and stir. Bring to a boil over medium-high heat. Add cinnamon, lower heat to medium-low and stir. Cover and let simmer for about 15 minutes, stirring occasionally until cranberries have become “sauce-like.” The consistency should be semi-thick. If it is too thin, uncover and continue to simmer until the right consistency is achieved. Take of heat and add pineapple tidbits and walnuts. Mix thoroughly.