小编Aug*_*nha的帖子

我正在研究Objective-C,我偶然发现了这个"for ... in"的声明.我搜索它但我仍然没有得到它的工作原理.有人可以用noob友好的方式向我解释这个陈述是如何运作的吗？

我正在尝试绘制一个以日期时间对象列表作为一个轴的图表。我在网上搜索了一下，看来我应该调用 date2num 函数。但是，当我调用它时，我收到属性错误。

这是我写的代码：

listOfDates
[datetime.date(2013, 8, 20), datetime.date(2013, 8, 21)]
dates = mathplotlib.dates.date2num(listOfDates)

这是我得到的错误：

Traceback (most recent call last):
File "<pyshell#30>", line 1, in <module>
  dates = matplotlib.dates.date2num(listOfDates)
AttributeError: 'module' object has no attribute 'dates'

非常感谢

我需要转换样式中的元组列表:

[(day1, name1, value1), (day2, name2, value2), (day3, name3, value3)]... etc

成:

[day1, day2, day3], [name1, name2, name3], [value1, value2, value3]... etc

目前我这样做:

vals is the list of tuples
day = []
name = []
value = []
for val in vals:
    day.append(val[0])
    name.append(val[1])
    value.append(val[2])

它有效,但它看起来很丑......我想知道是否有更"pythonic"的方式来实现相同的结果

我正在尝试创建一个简单的函数,它接受格式为int*int*int的两个日期,如果第一个比第二个更旧,则返回.

fun is_older (date1: (int*int*int), date2: (int*int*int)) =
    val in_days1 = (#1 (date1) * 365) + (#2 (date1) * 30) + #3 date1;
    val in_days2 = (#1 (date2) * 365) + (#2 (date2) * 30) + #3 date1;

    if in_days1 < in_days2
    then true
    else false

我收到此错误:

hwk_1.sml:1.53错误:语法错误:插入EQUALOP

未捕获的异常编译[编译:"语法错误"]

提出于:../ compiler/Pad /main/smlfile.sml:15.24-15.46

../compiler/TopLevel/interact/evalloop.sml:44.55

../compiler/TopLevel/interact/evalloop.sml:296.17-296.20

有人可以帮忙吗？

我在创建reddit对象时遇到此错误.这是代码:

import praw, requests, ctypes
r = praw.Reddit(user_agent="Wallpaper downloader")

这是错误:

Traceback(最近一次调用最后一次):

File "C:/Python27/background.py", line 3, in <module>
    r = praw.Reddit(user_agent="Wallpaper downloader")
  File "C:\Python27\lib\site-packages\praw\__init__.py", line 1028, in __init__
    super(AuthenticatedReddit, self).__init__(*args, **kwargs)
  File "C:\Python27\lib\site-packages\praw\__init__.py", line 502, in __init__
    super(OAuth2Reddit, self).__init__(*args, **kwargs)
  File "C:\Python27\lib\site-packages\praw\__init__.py", line 615, in __init__
    super(UnauthenticatedReddit, self).__init__(*args, **kwargs)
  File "C:\Python27\lib\site-packages\praw\__init__.py", line 280, in __init__
    self.handler = handler or DefaultHandler()
  File "C:\Python27\lib\site-packages\praw\handlers.py", line 70, in __init__
    self.http = Session()  # Each instance should have its own session
  File "C:\Python27\lib\site-packages\requests\sessions.py", line 176, …

我有这个 sqlalchemy 查询：

query = session.query(Store).options(joinedload('salesmen').
                                        joinedload('comissions').
                                        joinedload('orders')).\
        filter(Store.store_code.in_(selected_stores))

stores = query.all()
for store in stores:
    for salesman in store.salesmen:
        for comission in salesman.comissions:
            #generate html for comissions for each salesman in each store

#print html document using PySide

这工作得很好，但是我添加了两个新的过滤器查询：

        filter(Comissions.payment_status == 0).\
        filter(Order.order_date <= self.dateEdit.date().toPython())

如果我只添加第一个过滤器，应用程序会挂起几秒钟，如果我添加两个过滤器，应用程序会无限期挂起

我在这里做错了什么？如何快速进行此查询？

感谢您的帮助

编辑：这是生成的sql，不幸的是类和变量名称是葡萄牙语的，我只是将它们翻译成英语，这样会更容易理解，所以Loja = Store，Vendores = Salesmen，Pedido = Order，Commission = Comissao

生成的查询：

SELECT "Loja"."CodLoja", "Vendedores_1"."CodVendedor", "Vendedores_1"."NomeVendedor", "Vendedores_1"."CodLoja", "Vendedores_1"."PercentualComissao", 
"Vendedores_1"."Ativo", "Comissao_1"."CodComissao", "Comissao_1"."CodVendedor", "Comissao_1"."CodPedido", 
"Pedidos_1"."CodPedido", "Pedidos_1"."CodLoja", "Pedidos_1"."CodCliente", "Pedidos_1"."NomeCliente", "Pedidos_1"."EnderecoCliente", "Pedidos_1"."BairroCliente", 
"Pedidos_1"."CidadeCliente", "Pedidos_1"."UFCliente", "Pedidos_1"."CEPCliente", "Pedidos_1"."FoneCliente", "Pedidos_1"."Fone2Cliente", …

您需要将多少字节存储2^57,885,161 - 1为整数？