Python - 循環通過嵌套循環打印項目，如果它發生變化

Question

我正在循環幾個嵌套循環。如果它發生變化，我想打印第一個循環的項目。我怎樣才能做到這一點？

for slope in slopeList: 
    for yarddist in yardDistList: 
         for chiptreesperacre in chipAcreList: 
          for chipvolpertree in chipVolList: 
           for smalllognumber in smallAcreList: 
            for smalltreevolpertree in smallVolList: 
             for largelogperacre in largeAcreList: 
              for largetreevolpertree in largeVolList: 
               data = [slope, yarddist, chiptreesperacre, chipvolpertree, smalllognumber, smalltreevolpertree, largelogperacre, largetreevolpertree] 
               if slope changes: 
                print data 

Answer 1

商店的價值，你以前看到的，並加以比較：

previous_slope = None 
for slope in as_many_loops_as_you_like: 
    data = [slope, other_stuff] 
    if slope != previous_slope: 
     print data 
     previous_slope = slope 

Answer 2

你可以添加previous_slope到set和另外在內部循環後看它的長度：

slope = set() 
slope.add(previous_slope) 
old_length = len(slope) 
for first_loop: 
    slope.add(current_slope) 
    if len(slope) > old_length: 
    print 'Changed!' 
    break 

對每個內部循環重複此模式。