在python中绕过for循环中的ValueError

vlaaaaaddd • 3 年前 • 1351 次点击

def decade_total_count(decade, name):
    """
    sums up the number of births of the given 
    female baby `name` in a 10-year period
    
    Parameters:
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    decade ... starting year of the decade
    name   ... female name 
           ... str
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    """
    count = 0
    
    for i in range(decade, decade+10):
        yearly = females[(females['name']==name) & (females['year']==i)]['births'].item()
        count = count + yearly
        
    return count

我试图使用上面的函数来获取数据中任何名字的出生数,但只要有一年没有名字出现,我的循环就会停止。在这种情况下,我得到这个值错误:

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
/var/folders/yf/s14dt13x11n82t5kg4260v800000gn/T/ipykernel_4325/1603862037.py in <module>
----> 1 total_count('Jennifer')

/var/folders/yf/s14dt13x11n82t5kg4260v800000gn/T/ipykernel_4325/1143784105.py in total_count(name)
     42 
     43     for i in range(start, end, 10):
---> 44         counts.append(decade_total_count(i, name))
     45 
     46     return counts

/var/folders/yf/s14dt13x11n82t5kg4260v800000gn/T/ipykernel_4325/1143784105.py in decade_total_count(decade, name)
     15 
     16     for i in range(decade, decade+10):
---> 17         yearly = females[(females['name']==name) & (females['year']==i)]['births'].item()
     18         count = count + yearly
     19 

~/Desktop/anaconda3/lib/python3.9/site-packages/pandas/core/base.py in item(self)
    329         if len(self) == 1:
    330             return next(iter(self))
--> 331         raise ValueError("can only convert an array of size 1 to a Python scalar")
    332 
    333     @property

ValueError: can only convert an array of size 1 to a Python scalar

我如何绕过这个错误,即使在数据中不包含给定的“名称”的年份,也能保持循环?我跟你搞砸了 try , except , else 和 finally 子句,但不知怎的,它打破了我的循环,只返回0。

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1351 次点击

文章 [ 2 ] | 最新文章 3 年前

• 1 楼

Sean Xie 3 年前

你还没有表现出你的努力,所以我不知道你到底出了什么问题。然而,在循环中放置try-except块应该可以做到:

def decade_total_count(decade, name):
    """
    sums up the number of births of the given 
    female baby `name` in a 10-year period
    
    Parameters:
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    decade ... starting year of the decade
    name   ... female name 
           ... str
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    """
    count = 0
    
    for i in range(decade, decade+10):
        try:
            yearly = females[(females['name']==name) & (females['year']==i)]['births'].item()
            count = count + yearly
        except ValueError as e:
            print(f"Encountered error: {e}. Skipping.")
        
    return count

• 2 楼

Fed_Dragon 3 年前

抱歉,我没有足够的变量信息 female .

试试这个:

def decade_total_count(decade, name):
    """
    sums up the number of births of the given 
    female baby `name` in a 10-year period
    
    Parameters:
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    decade ... starting year of the decade
    name   ... female name 
           ... str
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    """
    count = 0
    
    for i in range(decade, decade+10):
        try:
            yearly = females[(females['name']==name) & (females['year']==i)]['births'].item()
        except ValueError:
            continue
        count = count + yearly
        
    return count

如果 ValueError 被提出,只需捕捉它并运行下一个迭代。

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