Write code in Python for matrix multiplication:

class MatMul(MRJob): #-------------------------- ''' Given a matrix A and a matrix B, compute the product A*B = C '''

#---------------------- @staticmethod def parse_line(line): ''' parse one line of text from the data file. Input: line: one line of text of a data record return: matrix_name: 'A' or 'B' i: row index, an integer (note, the index starts from 1) j: column index (note, the index starts from 1) v: the value of the entry; nr: number of rows in the matrix C nc: number of columns in the matrix C ''' matrix_name = line.split(',')[0] i = int(line.split(',')[1]) j = int(line.split(',')[2]) v = float(line.split(',')[3]) nr = int(line.split(',')[4]) nc = int(line.split(',')[5]) return matrix_name, i,j,v, nr, nc

#---------------------- def mapper(self, in_key, in_value): ''' mapper function, which process a key-value pair in the data and generate intermediate key-value pair(s) Input: in_key: the key of a data record (in this example, can be ignored) in_value: the value of a data record, (in this example, it is a line of text string in the data file, check 'matrix.csv' for example) Yield: (out_key, out_value) :intermediate key-value pair(s). You need to design the format and meaning of the key-value pairs. These intermediate key-value pairs will be feed to reducers, after grouping all the values with a same key into a value list. ''' # parse one line of text data matrix_name, i,j,v, nr, nc = self.parse_line(in_value)

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yield out_key, out_value

#---------------------- def reducer(self, in_key, in_values): ''' reducer function, which processes a key and value list and produces output key-value pair(s) Input: in_key: an intermediate key from the mapper in_values: a list (generator) of values , which contains all the intermediate values with the same key (in_key) generated by all mappers Yield: (out_key, out_value) : output key-value pair(s). ''' ######################################### ## INSERT YOUR CODE HERE

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