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And this is because I don't have something I would really like to have, which is data hiding.
也就是数据隐藏,你们会看到关于,这个概念的很多定义，我认为数据隐藏。
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I'm going to define a class, and in particular, what I'm going to do, is walk through what that says.
我们碰到了一个问题，这个问题就是，我们想要建立，一个抽象数据类型。
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As we all know, this only works if there is a pointee, which kind of gets back to rule number one.
众所周知，只有当有指针数据时，这个才起作用，这有点像第一条规则。
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Perhaps the data rate was a little bit faster than you were accustomed to, but you had some familiarity.
可能这个数据速度,相比你所熟悉的有些快，但是你有一些亲切感。
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There's a problem with that and the problem is that countries that are less successful don't keep data--that's a problem.
但这个研究方法也有问题,在那些不太成功的国家里,数据并不充分,这是个问题
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In class we'll have more data to present to you and we'll be eager to talk about some of the ways that people will be using the site and what the potential impact will be.
课堂上将会呈现更多的数据,我们渴望谈论,人们用这个网站的方法,以及潜在的影响。
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Four years later, as of today, 76% I think we have about 76% of the Chinese search traffic.
而四年之后的今天，这个数据已经上升到。
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they won't say, "Oh, because of this experiment, that experiment, " this data set and that data set."
他们不会说，“因为理论得到了这个实验，那个实验，这套数据，那套数据的支持“
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By 1852-53,Boston and New York think about this--Boston-- although we're getting close to that again Boston and New York had 50% foreign-born populations.
在1852年到1853年间,波士顿和纽约,你们听听这个数据,虽然我们现在又快接近这个比例了,那时移民占据波士顿和纽约人口的50%
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We did a study using the Framingham data ourselves several --some years ago where we were interested in the issue of weight cycling.
几年前我们用弗明汉研究的数据做过研究,我们对体重循环这个问题很感兴趣
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It's the various programs you run on your computer along with the various data files that you have saved on your hard drive,and so forth.
是你自身这个电脑中运行的各种程序,硬盘存有的各种数据和文件，类似种种。
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At least if we look at the statistics, just about every single one of you, after you leave Harvard,will join an organization, an organization that is a social enterprise, not for profit,something to better the world.
看一下统计数据，你们每个人，离开哈佛后，都将加入公司，这个组织是个社会企业，非盈利机构，只为贡献社会而存在的。
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We want to have that definition clear because in fact we're going to, we might want tabulate heats of reaction, right, and of course want to know what the conditions are for the tabulated values apply. And we're going to want to calculate them from other quantities and again, we're going to need to know each case what are the relevant conditions?
我们想要明确这个定义,因为实际上我们会想把,反应热制成表格，当然我们会,想知道表中的数据在什么样的,条件下是有效的，我们会,想要从其他的量中算出它们,再一次，我们需要知道,每种情形下相关的条件是什么？
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Again, I don't have data to back this up, but just common sense suggests to me that the common case is if I'm on the subway platform I want to get on that train and maybe I want to get back and where are those two buttons, right?
此外，我没有数据来备份这个，但是常识告诉我，常见的情况是,如果我站在地铁站台上，我想乘上地铁,可能我还想回来,那么哪里能找到这两个按钮，对不？
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So in fact, it is the case, if you look at data, and by the way, that's the way I ended up setting a lot of these parameters and playing with it, was comparing what my simulation said to historical stock data.
所以实际上，在这个例子中，如果你看到数据，顺便说一下，这就是我设置很多变量,然后编程的方式，也就是把我的仿真程序得到的结果,和历史股票数据进行比较。
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x >> Okay. I'll dereference the pointer x 42 to store the number 42 into its pointee.
>，好的，我废除这个指针,在指针数据中存储数字。
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I shouldn't put down a name of a company because I can't reproduce this diagram for Microsoft.
我不应该用这个公司名,因为我没法重现它的数据
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Now we have all this data, and this Aristotelian model is looking goofier and goofier.
现在我们拥有这些数据，这个亚里士多德模型,看起来已经越来越愚蠢了。
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In our--in this particular study we had some people estimate things low and some people estimate things high, but overall, this--these would represent overestimates.
在这个实验中,有些人低估了,而有些人高估了数据,但总体来说,结果显示人们高估了数据
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I've added the ability to have more complex data structures here. But I dropped a hint in the first lecture about what you could computer with things. In fact if you think for a second about that list, you could ask what can I compute with just that set of constructs?
我添加了使用更复杂的数据结构的能力,但是我在第一节课给大家了了一个,关于你可以用什么来做计算的暗示,实际上如果你思考,这个列表一会儿的话,你会问我可以用？
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You try to design actually I'm going to come back to that in a second. It's like you're trying to use a hash function that spread things out pretty evenly. But the places you store into in those lists may have to themselves have a small list in there, and when you go to check something, you may have to do a linear search through the elements in that list.
你尝试着去设计,实际上过会儿我会回头讲解这个问题,类似于你需要用一个哈希函数,非常平均的将物体分发出去,但是在列表中你数据,映射到的地方可能会有自己的一小段列表，当你回头查找数据的时候,你可能需要在那一小段列表中做线性查找。
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I don't find that my analysis is profound in the final answer, I just took some estimates using my data and, again, we could-- if someone wanted to argue with us they could argue with my estimates of the expected returns of the standard deviations and the covariances, but not with this theory.
我在计算过程中并没有做太深入的分析，我只是用我的数据做了一下大概的估计,我再说一次，我们可以-,如果有人想就这个问题与我们争辩,他们可以争论我对期望收益的估计,或是争论标准差和协方差的估计值，但并不会针对理论本身。
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So but the diary is a way to get more sophisticated information on individuals for dietary counseling purposes and the like, but it's pretty labor intensive and then it requires either a computer to analyze the diet or some human being who is trained in this to sit down and make sense of the data.
日记这个办法,可获得更加精确的个体信息,用以进行饮食咨询等,但这更像是劳动密集型工作,然后还需要一台电脑,来分析食物数据,有些人学的就是,坐在电脑前弄明白这些数据
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Instead if we want this pointer to represent the address of something in as much as it points at that address let's just draw an arrow.
如果我们想要让这个指针表示,数据的地址，它指向的地址,我用一个箭头表示。
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Toward the end of the semester, we'll talk about database design.
到这个学期的期末，我们会讨论数据库的设计。
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> No, this doesn't touch the pointees.
>，不会，这个不会触及到指针数据。
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That's what I got using this sample period.
这就是用这个取样期间的数据得出的结果。
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Where do I have that here?
我找找这个数据
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I don't have the latest data -this is from 1998 -but there were 11,000 credit unions -that's the number of credit unions in the United States in 1998 -and there were only 9,000 commercial banks; that's the number of banks.
我手上没有最新的数据,这个是1998年的,共有11000个信用合作社,这是1998年全美信用合作社的数量,与此同时,商业银行只有9000家,这是银行的数量
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So we're to assume we can get to any piece of data, any instruction in constant time, and the second assumption we're going to make is that the basic primitive steps take constant time, same amount of time to compute. Again, not completely true, but it's a good model, so arithmetic operations, comparisons, things of that sort, we're all going to assume are basically in that in that particular model.
因此如果我们假设在恒定的时间内,我们可以取得任何一块数据,任何一种数据结构的话,我们要做的第二个假设就是,基本的原始操作计算花费的时间是恒定的,这个假设也不是完全正确的，但这个模型其实挺不错的，因此算法操作，比较，这一类的事情，我们在这个特定的模型中都假设是基本的,操作，花费的时间是恒定相同的。
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