嵌套循環全部

Question

我正在使用python。這個任務很簡單，我理解這個概念，我對計算機編程毫無知識，所以請溫和一些，並且儘量詳細地解釋一切，就好像我什麼都不知道，我正在努力學習。這表明用所有組合ijk，ikj，jik，jki，kij和kji返回相同的結果。下一步是用4000做同樣的事情（試着想象如何把4000放在矩陣中，拍攝自己。） 我知道有些東西像numpy，但我不知道如何使用它，但是我打算嘗試從基礎開始，直接從Windows終端。我想感謝你的時間，並幫助這裏的傢伙！謝謝！在這裏輸入

enter code here 

    X = [[1,2,3,4,5], 
     [6,7,8,9,10]] 



    Y = [[1,2], 
     [3,4], 
     [5,6], 
     [7,8], 
     [9,10]] 



    result = [[0,0], 
      [0,0]] 
    empty = [[0,0], 
      [0,0]] 

     for i in range(len(X)): 
      for j in range(len(Y[0])): 
        for k in range(len(Y)): 
         result[i][j] += X[i][k] * Y[k][j] 
for r in result: 
    print r 
    result = empty 
    del r[:] 


print"" 

for i in range(len(X)): 
    for k in range(len(Y)): 
     for j in range(len(Y[0])): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
    del r[:] 


print"" 

for i in range(len(X)): 
    for k in range(len(Y)): 
     for j in range(len(Y[0])): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
    result = empty 
    del r[:] 
    del range[:] 

print"" 

for j in range(len(Y[0])):  
    for i in range(len(X)): 
     for k in range(len(Y)): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
    result = empty 
    del r[:] 

for j in range(len(Y[0])): 
    for k in range(len(Y)): 
     for i in range(len(X)): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
    result = empty 
    del r[:] 

for k in range(len(Y)): 
    for i in range(len(X)): 
     for j in range(len(Y[0])): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
    result = empty 
    del r[:] 

for k in range(len(Y)): 
    for j in range(len(Y[0])): 
     for i in range(len(X)): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
    result = empty 
    del r[:] 

問題代碼，是該指數，爲第3集運行代碼的時候，沒有與該指數的一個問題，我不明白這一點。

  result[i][j] += X[i][k] * Y[k][j] 
     IndexError: list index out of range 

Answer 1

for i in range(len(X)): 
    for k in range(len(Y)): 
     for j in range(len(Y[0])): 
      result[i][j] += X[i][k] * Y[k][j] 

result[i][j]是2x2矩陣len(X)和len(Y)均爲2。同時k一路高達5。這是什麼給你你的list index out of range錯誤

你必須使你的矩陣大小匹配。

Answer 2

我打印i，j，k和result[i][j]，X[i][k]，Y[k][j]在第三組發現：

你忘result = empty

但還有另一個問題：result = empty不重複名單，而是將相同列表爲兩個變量。因此，當您刪除r[:]時，您將刪除result和empty，並獲得空列表[]並且甚至不存在result[0][0]。

您需要result = empty[:]才能複製empty並指定爲result。

X = [[1,2,3,4,5], 
    [6,7,8,9,10]] 

Y = [[1,2], 
    [3,4], 
    [5,6], 
    [7,8], 
    [9,10]] 

result = [[0,0], 
     [0,0]] 

empty = [[0,0], 
     [0,0]] 


for i in range(len(X)): 
    for j in range(len(Y[0])): 
      for k in range(len(Y)): 
       result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
print 

result = empty[:] 

for i in range(len(X)): 
    for k in range(len(Y)): 
     for j in range(len(Y[0])): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
print 

result = empty[:] 

for i in range(len(X)): 
    for k in range(len(Y)): 
     for j in range(len(Y[0])): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
print 

result = empty[:] 

for j in range(len(Y[0])):  
    for i in range(len(X)): 
     for k in range(len(Y)): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
print 

result = empty[:] 

for j in range(len(Y[0])): 
    for k in range(len(Y)): 
     for i in range(len(X)): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
print 

result = empty[:] 

for k in range(len(Y)): 
    for i in range(len(X)): 
     for j in range(len(Y[0])): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
print 

result = empty[:] 

for k in range(len(Y)): 
    for j in range(len(Y[0])): 
     for i in range(len(X)): 
      result[i][j] += X[i][k] * Y[k][j] 

for r in result: 
    print r 
print 

result = empty[:]