Question

我正在尝试更新在方法/函数开始时初始化的字典，以后应使用函数中的计数器变量更新键的相应值。但是，由于某些原因，我的词典没有更新。请告知。

代码：

def quizresult(quiz_df):
maxmarks=10.0
noofpresent,lessthanfifty,betweenfiftyandsixty,betweensixtyandseventy,betweenseventyandeighty,greaterthaneighty=0.0,0.0,0.0,0.0,0.0,0.0
quiz_result={'noofpresent':None,'lessthan50':None,'between50and60':None,'between60and70':None,'between70and80':None,'greaterthan80':None}
for i in range(len(quiz_df)):

    noofpresent=len(quiz_df.index)
    if(float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)<0.5:
        lessthanfifty += 1
    if((float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)>=0.5 and (float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)<0.6):
        betweenfiftyandsixty += 1
    if((float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)>=0.6 and (float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)<0.7):
        betweensixtyandseventy += 1
    if((float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)>=0.7 and (float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)<0.8):
        betweenseventyandeighty += 1
    if(float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)>=0.8:
        greaterthaneighty += 1
quiz_result.update({'noofpresent':noofpresent,'lessthan50':lessthanfifty,'between50and60':betweenfiftyandsixty,'between60and70':betweensixtyandseventy,'between70and80':betweenseventyandeighty,'greaterthan80':greaterthaneighty})

return quiz_result

P.S：缩进在这里不是问题。我收到以下消息：

“ SettingWithCopyWarning：试图在DataFrame的切片副本上设置一个值。尝试改用.loc [row_indexer，col_indexer] = value

请参阅文档中的警告：http://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copy 从sys.path中删除cwd之后。”

Answer 1

您可以手动执行以下操作，以使用计数器变量更新字典的值。例如，

quiz_result['noofpresent'] = noofpresent #You can do the following for all other keys.

编辑：

您能尝试以下代码并告诉我会发生什么吗？请保留缩进。除此之外，还要确保len（quiz_df）> 0。

def quizresult(quiz_df):
    maxmarks=10.0
    noofpresent,lessthanfifty,betweenfiftyandsixty,betweensixtyandseventy,betweenseventyandeighty,greaterthaneighty=0.0,0.0,0.0,0.0,0.0,0.0
    quiz_result={'noofpresent':0,'lessthan50':0,'between50and60':0,'between60and70':0,'between70and80':0,'greaterthan80':0}
    for i in range(len(quiz_df)):

        noofpresent=len(quiz_df.index)
        if(float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)<0.5:
            lessthanfifty += 1
        if((float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)>=0.5 and (float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)<0.6):
            betweenfiftyandsixty += 1
        if((float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)>=0.6 and (float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)<0.7):
            betweensixtyandseventy += 1
        if((float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)>=0.7 and (float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)<0.8):
            betweenseventyandeighty += 1
        if(float(quiz_df.loc[i,'Grade/10.00'])/maxmarks)>=0.8:
            greaterthaneighty += 1
    quiz_result.update(noofpresent =noofpresent ,lessthan50=lessthanfifty ,between50and60=betweenfiftyandsixty,between60and70=betweensixtyandseventy, between70and80=betweenseventyandeighty,greaterthan80= greaterthaneighty)

return quiz_result

我确信您的错误与循环未运行或循环内的条件语句失败有关，因此不会增加值

Answer 2

您确定缩进正确吗？我运行了以下代码，并获得了预期的字典（字典值为0.0）：

date = [self.tableWidget.item(row, 0).text() for row in range(self.tableWidget.rowCount())]
name = [self.tableWidget.item(row, 1).text() for row in range(self.tableWidget.rowCount())]

location = [self.tableWidget.item(row, 2).text() for row in range(self.tableWidget.rowCount())]
item1 = [self.tableWidget.item(row, 3).text() for row in range(self.tableWidget.rowCount())]
item2 = [self.tableWidget.item(row, 4).text() for row in range(self.tableWidget.rowCount())]
item3 = [self.tableWidget.item(row, 5).text() for row in range(self.tableWidget.rowCount())]
item4 = [self.tableWidget.item(row, 6).text() for row in range(self.tableWidget.rowCount())]
item5 = [self.tableWidget.item(row, 7).text() for row in range(self.tableWidget.rowCount())]
item6 = [self.tableWidget.item(row, 8).text() for row in range(self.tableWidget.rowCount())]
conn = sqlite3.connect('test.db')
conn.execute("INSERT INTO maintable(date,name,location,item1,item2,item3,item4,item5,item6) \
     VALUES ('%s', '%s','%s', '%s', '%s', '%s', '%s', '%s', '%s')" %(''.join(date),
                                                                     ''.join(name),
                                                                     ''.join(location),
                                                                     ''.join(item1),
                                                                     ''.join(item2),
                                                                     ''.join(item3),
                                                                     ''.join(item4),
                                                                     ''.join(item5),
                                                                     ''.join(item6)))

循环运行后，使用字典的值更新多个键，并更新用于更新字典的值

2 个答案: