避免在Python中使用多个Try/Except块 [英] Avoiding Multiple Try/Except blocks in Python

问题描述

我有一个有效的代码，但是发现拥有大量try/except块来处理异常非常低效.有一个更好的方法吗?

I have a working code but find that having numerous try/except blocks to handle exceptions very inefficient. Is there a better way to do this?

我当前使用的代码粘贴在下面.我应该执行自定义函数还是for循环?如何创建一个?

The code that I am currently using is pasted below. Should I do a custom function or for loops? How do I create one?

由于要求，代码已被缩短...

Code has been cut short due to requirements...

rows = []
rows.append(['Name','Weight', 'Height', 'Season', 'Age', 'Tm', 'Lg', 'Pos', 'G', 'GS', 'MP', 'FG', 'FGA' , 'FGP' , 'P3' , 'PA3' , 'PP3' , 'P2' , 'PA2', 'PP2', 'eFGP' , 'FT', 'FTA' , 'FTP', 'ORB', 'DRB' , 'TRB', 'AST' , 'STL', 'BLK', 'TOV', 'PF' , 'PTS'])

for result in results[1:len(results)]:
    Name = soup.find(name="h1", attrs={"itemprop":"name"}).text.strip()
    Weight = soup.find(name="span", attrs={"itemprop":"weight"}).text.strip()
    Height = soup.find(name="span", attrs={"itemprop":"height"}).text.strip()
    # find all columns per result

    # data = result.find_all('td')
    try:
        season = result.find_all('a')[0]
        season = season.getText()
    except:
        season = 'NA'
    # check that columns have data 
        # if len(data) == 0: 
            # continue
    Season = season
    Age_find = result.find_all('td', attrs={'data-stat': 'age'})
    Tm_find = result.find_all('td', attrs={'data-stat': 'team_id'})
    Lg_find = result.find_all('td', attrs={'data-stat': 'lg_id'})
    Pos_find = result.find_all('td', attrs={'data-stat': 'pos'})
    G_find = result.find_all('td', attrs={'data-stat': 'g'})
    GS_find = result.find_all('td', attrs={'data-stat': 'gs'})
    MP_find = result.find_all('td', attrs={'data-stat': 'mp_per_g'})
    FG_find = result.find_all('td', attrs={'data-stat': 'fg_per_g'})
    FGA_find = result.find_all('td', attrs={'data-stat': 'fga_per_g'})
    FGP_find = result.find_all('td', attrs={'data-stat': 'fg_pct'})
    P3_find = result.find_all('td', attrs={'data-stat': 'fg3_per_g'})
    PA3_find = result.find_all('td', attrs={'data-stat': 'fg3a_per_g'})
    PP3_find = result.find_all('td', attrs={'data-stat': 'fg3_pct'})
    P2_find = result.find_all('td', attrs={'data-stat': 'fg2_per_g'})
    PA2_find = result.find_all('td', attrs={'data-stat': 'fg2a_per_g'})
    PP2_find = result.find_all('td', attrs={'data-stat': 'fg2_pct'})
    eFGP_find = result.find_all('td', attrs={'data-stat': 'efg_pct'})
    FT_find = result.find_all('td', attrs={'data-stat': 'ft_per_g'})
    FTA_find = result.find_all('td', attrs={'data-stat': 'fta_per_g'})
    FTP_find = result.find_all('td', attrs={'data-stat': 'ft_pct'})
    ORB_find = result.find_all('td', attrs={'data-stat': 'orb_per_g'})
    DRB_find = result.find_all('td', attrs={'data-stat': 'drb_per_g'})
    TRB_find = result.find_all('td', attrs={'data-stat': 'trb_per_g'})
    AST_find = result.find_all('td', attrs={'data-stat': 'ast_per_g'})
    STL_find = result.find_all('td', attrs={'data-stat': 'stl_per_g'})
    BLK_find = result.find_all('td', attrs={'data-stat': 'blk_per_g'})
    TOV_find = result.find_all('td', attrs={'data-stat': 'tov_per_g'})
    PF_find = result.find_all('td', attrs={'data-stat': 'pf_per_g'})
    PTS_find = result.find_all('td', attrs={'data-stat': 'pts_per_g'})

    try:
        Age = Age_find[0].getText()
    except:
        Age = 'NA'

    try:
        Tm = Tm_find[0].getText()
    except:    
        Tm = 'NA'

    try:
        Lg = Lg_find[0].getText()
    except:    
        Lg = 'NA'

    try:
        Pos = Pos_find[0].getText()
    except:    
        Pos = 'NA'

    try:
        G = G_find[0].getText()
    except:
        G = 'NA'

    try:
        GS = GS_find[0].getText()
    except:    
        GS = 'NA'

    try:
        MP = MP_find[0].getText()
    except:    
        MP = 'NA'

    try:
        FG = FG_find[0].getText()
    except:    
        FG = 'NA'

    try:
        FGA = FGA_find[0].getText()
    except:    
        FGA = 'NA'

    try:
        FGP = FGP_find[0].getText()
    except:    
        FGP = 'NA'

    try:    
        P3 = P3_find[0].getText()
    except:    
        P3 = 'NA'

    try:
        PA3 = PA3_find[0].getText()
    except:    
        PA3 = 'NA'

    try:
        PP3 = PP3_find[0].getText()
    except:    
        PP3 = 'NA'

    try:
        P2 = P2_find[0].getText()
    except:    
        P2 = 'NA'

    try:
        PA2 = PA2_find[0].getText()
    except:    
        PA2 = 'NA'

    try:
        PP2 = PP2_find[0].getText()
    except:    
        PP2 = 'NA'

    try:    
        eFGP = eFGP_find[0].getText()
    except:    
        eFGP = 'NA'

    try:    
        FT = FT_find[0].getText()
    except:    
        FT = 'NA'

    try:
        FTA = FTA_find[0].getText()
    except:    
        FTA = 'NA'

    try:
        FTP = FTP_find[0].getText()
    except:    
        FTP = 'NA'

    try:
        ORB = ORB_find[0].getText()
    except:    
        ORB = 'NA'

    try:    
        DRB = DRB_find[0].getText()
    except:    
        DRB = 'NA'

    try:
        TRB = RRB_find[0].getText()
    except:    
        TRB = 'NA'

    try:
        AST = AST_find[0].getText()
    except:    
        AST = 'NA'


    rows.append([Name, Weight, Height, Season, 
                 Age, Tm, Lg, Pos, G, GS, MP, FG, FGA, 
                 FGP, P3, PA3, PP3, P2, PA2, PP2, eFGP, FT,
                 FTA , FTP, ORB, DRB, TRB, AST, STL, BLK, TOV, PF, PTS])

with open('player_zaid.csv','w', newline='') as f_output:
    csv_output = csv.writer(f_output)
    csv_output.writerows(rows)

推荐答案

您有很多代码节基本上可以完成相同的工作，这违反了不要重复自己(DRY)的原则.避免重复的通常方法是编写一个隐藏重复的函数.

You have many sections of code that do basically the same thing, which violates the Don't Repeat Yourself (DRY) principle. The usual way to avoid that repetition is to write a function to hide the repetition.

def get_text_or_NA(container):
    try:
        result = container[0].getText()
    except:
        result = 'NA'
    return result

那么您的基本代码是

Age = get_text_or_NA(Age_find)
Tm = get_text_or_NA(Tm_find)
Lg = get_text_or_NA(Lg_find)

以此类推.

您可以采用类似的方法删除代码中的其他重复-我会将这些重复留给您.正如@roganjosh的评论所指出的那样，在没有给出异常的情况下，您实际上不应该使用 except:.您的方式掩盖了所有问题.更具体些，只隐藏您期望的异常，这样可以在更高层次上捕获意外的异常.

You could similar means to remove other repetitions in your code--I'll leave those to you. And as the comment from @roganjosh states, you really should not use except: without giving an exception. Your way just hides all problem. Be more specific and hide only the exceptions you expect, so unexpected ones can be caught at a higher level.

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