如何使用MapReduce在python中相乘矩阵？

Question

假设我有两个如下所示的2X2矩阵。

A,0,0,1
A,0,1,0
A,1,0,0
A,1,1,1
B,0,0,2
B,0,1,3
B,1,0,4
B,1,1,5

例如，B,1,0,4表示矩阵B，行1，列0，值4。

如何使用MapReduce方法获取此输出：

0,0,2
0,1,3
1,0,4
1,1,5

Answer 1

我制作了一个cache.txt文件来输入矩阵的尺寸。 （row_a，col_b，col_a）

input.txt包含矩阵。

下面是代码。

cache_info = open("cache.txt").readlines()[0].split(",")
row_a, col_b, col_a = map(int, cache_info)

mapperOutput = open("mapperOutput.txt", "w")

for line in open("input.txt"):
    matrix_index, row, col, value = line.rstrip().split(",")
    if matrix_index == "A":
        for i in range(0, col_b):
            key = row + "," + str(i)
            mapperOutput.write("%s\t%s\t%s" % (key, col, value) + "\n")
    else:
        for j in range(0, row_a):
            key = str(j) + "," + col
            mapperOutput.write("%s\t%s\t%s" % (key, row, value) + "\n")
mapperOutput.close()

numbers1 = list()
for line in open("mapperOutput.txt"):
    curr_index, index, value = line.rstrip().split("\t")
    index, value = map(int, [index, value])
    numbers1.append((curr_index, index, value))
numbers2 = numbers1
initValue1 = list()
initValue2 = list()
for i in numbers1:
    checker = 0
    for j in numbers2:
        if i == j:
            if checker == 0:
                checker += 1
                continue
        if i[0] == j[0]:
            if i[1] == j[1]:
                initValue1.append([i[0],str(i[1]),i[2]*j[2]])

initValue2 = initValue1
myOut = dict()
counter = 0
for i in initValue1:
    if counter > (row_a*col_b*col_a):
        break
    if i[0] in myOut.keys():
        counter += 1
        continue
    counter += 1
    myOut[i[0]] = i[2]
    inercounter = 0
    for j in initValue2:
        if i[0] == j[0]:
            if i[1] != j[1]:
                inercounter += 1
                if inercounter > col_b - 1:
                    continue
                myOut[i[0]] += j[2]

for key,value in myOut.items():
    print(key,value)

输出将是：

0,0 2
0,1 3
1,0 4
1,1 5