xtsInternals(xts)
xtsInternals()所属R语言包：xts
Internal Documentation
内部文件
译者：生物统计家园网 机器人LoveR
描述----------Description----------
This help file is to help in development of xts, as well as provide some clarity and insight into its purpose and implementation.
此帮助文件是帮助XTS的发展，以及提供一些清晰和洞察其目的和实现。
Last modified: 2008-08-06 by Jeffrey A. Ryan Version: 0.5-0 and above
最后更新：2008-08-06由Jeffrey A.瑞安版本：0.5-0及以上
The xts package xts designed as a drop-in replacement for the very popular zoo package. Most all functionality of zoo has been extended or carries into the xts package.
xts包XTS下降的替代品非常流行的zoo包。几乎所有功能的动物园一直延伸到XTS包或进行。
Notable changes in direction include the use of time-based indexing, at first explicitely, now implicitely.
显着的变化方向，包括使用基于时间的索引，第一次明确地，现在implicitely。
An xts object consists of data in the form of a matrix, an index - ordered and increasing, either numeric or integer, and additional attributes for use internally, or for end-user purposes.
一个xts对象组成中的数据的形式的矩阵，一个索引 - 订购和增加，无论是数字或整数，和额外的属性为内部使用，或为最终用户的目的。
The current implementation enforces two major rules on the object. One is that the index must be coercible to numeric, by way of as.POSIXct. There are defined types that meet this criteria. See timeBased for details.
目前实施强制执行的对象的两个主要规则。其一是该指数必须转换成数字方式的as.POSIXct。有符合此标准的定义的类型。见timeBased的详细信息。
The second requirement is that the object cannot have rownames. The motivation from this comes in part from the work Matthew Doyle has done in his data.table class, in the package of the same name. Rownames in R must be character vectors, and as such are inefficient in both storage and conversion. By eliminating the rownames, and providing a numeric index of R internal type REAL or INTEGER, it is possible to maintain a connection to standard R date and time classes via the POSIXct functions, while at at the same time maximizing efficiencies in data handling.
第二个要求是，该对象可以没有行名。这样做的动机是在马修·多伊尔已完成在他的data.table类，包中的相同名称的工作的一部分。行名R中必须是字符向量，并作为这些都是在两个存储和转换效率低下。通过消除的行名，并提供一个数字索引R内部类型REAL或INTEGER，它能够维持一个连接到标准的R日期和时间类经由POSIXct功能，同时在同一时间，最大限度地提高数据处理的效率。
User level functions index, as well as conversion to other classes proceeds as if there were rownames. The code for index automatically converts time to numeric in both extraction and replacement functionality. This provides a level of abstraction to facilitate internal, and external package use and inter-operability.
用户级的功能，index，以及转换成其他类所得款项，如果有行名。 index自动将时间数字的提取和替换功能的代码。这提供了一个抽象层，以方便内部和外部的程序包使用和互操作性。
There is also new work on providing a C-level API to some of the xts functionality to facilitate external package developers to utilize the fast utility routines such as subsetting and merges, without having to call only from R. Obviously this places far more burden on the developer to not only understand the internal xts implementation, but also to understand all of what is documented for R-internals (and much that isn't). At present the functions and macros available can be found in the "xts.h" file in the src directory.
C级API提供一些的XTS功能的，以方便外部包开发人员能够利用快速的实用程序，如子集和合并，而无需调用只能从R.显然，这更多的负担，也有新的工作开发人员不仅要了解内部XTS实现，而且要了解所有的东西记录R-内部（很多是没有）。目前可用的函数和宏，可以发现在“xts.h”的文件，在src目录下。
There is no current documentation for this API. The adventure starts here. Future documentation is planned, not implemented.
目前没有任何此API的文档。冒险从这里开始。未来的计划文件，未实现。
（作者）----------Author(s)----------
Jeffrey A. Ryan
转载请注明:出自 生物统计家园网(http://www.biostatistic.net)。
注：
注1：为了方便大家学习，本文档为生物统计家园网机器人LoveR翻译而成，仅供个人R语言学习参考使用，生物统计家园保留版权。
注2：由于是机器人自动翻译，难免有不准确之处，使用时仔细对照中、英文内容进行反复理解，可以帮助R语言的学习。
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发表于 2012-10-2 07:28:50
