将两个多维列表相乘

Question

For example,

Price = [['1', '5'], ['4', '9']]

Quantity = [['50.00', '0'], ['10.00', '20.00']]

want to have

Revenue = [['50.00', '0'], ['40.00', '180.00']]

Tried using list comprehension, but don't know how it works for this two-dimension lists.

Answer 1

You can do so without any modules by using the built-in function zip :

Revenue = []
for ps, qs in zip(Price, Quantity):
    rs = []
    for p, q in zip(ps, qs):
        rs.append('%.2f' % (float(p) * float(q)))
    Revenue.append(rs)

Answer 2

Using list comprehensions

>>> [ [str(float(p[0]) * float(q[0])), str(float(p[1]) * float(q[1]))]  for p, q in 
zip(price, quantity) ]
[['50.0', '0.0'], ['40.0', '180.0']]

Answer 3

不是最易读的，但可能有一种衬纸可以做到这一点：

Revenue = [map(lambda (price,quantity) : str(float(price)*float(quantity)), zip(Price[i],Quantity[i])) for i in range(len(Price))]

Answer 4

This is easy and obvious to write in Numpy (or Pandas ) if either of these an option for you, then it's just:

Revenue = Price*Quantity

In the full program:

import numpy as np
Price = np.array( [[1, 5], [4, 9]] )
Quantity = np.array( [[50.0, 0], [10.00, 20.00]] )

Revenue = Price*Quantity

# [[  50.    0.]
#  [  40.  180.]]

Note, that here I abandoned the OP's string notation. I assume that it's a beginner's mistake, and that they want numbers to be numbers, and plan on doing more calculations than this simple one.