阿呆錯誤 - 沒有看到它

Question

我有浮點值數據集：

dog-auto  dog-bird  dog-cat   dog-dog   Result 
41.9579761457 41.7538647304 36.4196077068 33.4773590373 0 
46.0021331807 41.33958925  38.8353268874 32.8458495684 0 
42.9462290692 38.6157590853 36.9763410854 35.0397073189 0 
41.6866060048 37.0892269954 34.575072914 33.9010327697 0 
39.2269664935 38.272288694 34.778824791 37.4849250909 0 
40.5845117698 39.1462089236 35.1171578292 34.945165344 0 
45.1067352961 40.523040106 40.6095830913 39.0957278345 0 
41.3221140974 38.1947918393 39.9036867306 37.7696131032 0 
41.8244654995 40.1567131661 38.0674700168 35.1089144603 0 
45.4976929401 45.5597962603 42.7258732951 43.2422832585 0 

這是一個SFrame。我試圖編寫一個函數，使用if/an語句來確定dog-dog的值是否小於dog-ct和dog-auto和dog-bird的值。

我已經經歷了這個4小時的更好的一部分。無可否認，我是Python的新手 - 我犯了一個錯誤，只是沒有看到它。

如果聲明：

def is_dog_correct(row): 
    if (dog_distances[dog_distances['dog-dog']] < dog_distances[dog_distances['dog-cat']]) & (dog_distances[dog_distances['dog-dog']] < dog_distances[dog_distances['dog-bird']]) & (dog_distances[dog_distances['dog-dog']] < dog_distances[dog_distances['dog-auto']]): 
     dog_distances['Result'] = 1 
    else: 
     dog_distances['Result'] = 0 

然後我調用函數：

dog_distances.apply(is_dog_correct) 

如果這是正常工作，我會看到「0」中的每一行，但第五記錄英寸我的if語句有什麼問題？

完全披露 - 這是課程，但花了4個小時後，我正在尋求幫助！

Answer 1

將&更改爲並且如前面的評論所示。另外，我建議你把這樣長的if語句分成多行，這樣它就更清晰易讀了。

def is_dog_correct(row): 
    if (dog_distances[dog_distances['dog-dog']] < dog_distances[dog_distances['dog-cat']]) and 
     (dog_distances[dog_distances['dog-dog']] < dog_distances[dog_distances['dog-bird']]) and 
     (dog_distances[dog_distances['dog-dog']] < dog_distances[dog_distances['dog-auto']]): 
     dog_distances['Result'] = 1 
    else: 
     dog_distances['Result'] = 0 

Answer 2

通過查找所有值的min（最小值），使您的第一條語句更加乾淨。這可以確保「狗狗」小於所有的休息：

def is_dog_correct(row): 
    if dog_distances[dog_distances['dog-dog']] < min([dog_distances[dog_distances['dog-'+x]] for x in ['cat','bird','auto']]): 
     dog_distances['Result'] = 0 
    else: 
     dog_distances['Result'] = 1 

編輯：對於debuggin目的使用以下命令：

def is_dog_correct(row): 
    print 'dog is {}'.format(dog_distances[dog_distances['dog-dog']]) 
    print 'everyone else is {}'.format([dog_distances[dog_distances['dog-'+x]] for x in ['cat','bird','auto']]) 
    if dog_distances[dog_distances['dog-dog']] < min([dog_distances[dog_distances['dog-'+x]] for x in ['cat','bird','auto']]): 
     print 'Yay dog is faster' 
     dog_distances['Result'] = 0 
    else: 
     print 'Awww, dog is not faster' 
     dog_distances['Result'] = 1