Python是忽略我的if

Question

有人能告訴我爲什麼這個循環忽略了if？ （編輯：這是整個代碼 - 這還給了一些功能。）

time_now = time() 
number = np.loadtxt("11.txt", unpack=True, dtype='int64') 
lenx = len(number[0,:]) 
leny = len(number[:,0]) 
lennum = 4 
#prods = np.zeros(lenx*leny*4).reshape(lenx,leny,4) 
maxnum = 0 

for m in range(0,leny): 
    for n in range(0,lenx): 
     prods = lookaround(n,m) 

     if prods > maxnum: 
      maxnum = prods 

time_end = time(); 

elapsed = time_end - time_now 

print(prods, elapsed) 

Answer 1

也許是因爲prods始終小於或等於maxnum？你用什麼值初始化maxnum？它應該設置在循環之前的非常小的數字上，比如maxnum = float("-inf")。另一種可能是lookaround正在返回一個不正確的值，即單元測試函數。

Answer 2

你可以只寫它：

from itertools import product 

time_now = time() 

number = np.loadtxt("11.txt", unpack=True, dtype='int64') 
lenx = len(number[0,:]) 
leny = len(number[:,0]) 

maxnum = max(lookaround(n, m) for n, m in product(range(lenx), range(leny))) 

time_end = time();  
elapsed = time_end - time_now 

print(maxnum, elapsed) # <== maxnum not prods