如何在R中获得一个大的稀疏矩阵？ （> 2 ^ 31-1） [英] How to get a big sparse matrix in R? (> 2^31-1)
问题描述
我使用一些C ++代码从数据库中获取文本文件，并从 Matrix 包中创建dgcMatrix类型的稀疏矩阵。我第一次尝试建立一个具有2 ^ 31-1个以上非稀疏成员的矩阵，这意味着稀疏矩阵对象中的索引向量也必须长于该限制。不幸的是，向量似乎使用32位整数索引，Rcpp中的NumericVectors也是如此。
I use some C++ code to take a text file from a database and create a dgcMatrix type sparse matrix from the Matrix package. For the first time, I'm trying to build a matrix that has more than 2^31-1 non-sparse members, which means that the index vector in the sparse matrix object must also be longer than that limit. Unfortunately, vectors seem to use 32-bit integer indices, as do NumericVectors in Rcpp.
从头开始编写全新的数据类型，R是否为此提供任何便利？我认为我不能使用过于奇特的解决方案，因为我需要 glmnet 来识别生成的对象。
Short of writing an entire new data type from the ground up, does R provide any facility for this? I don't think I can use too exotic a solution as I need glmnet to recognize the resultant object.
推荐答案
在R的最新版本中，矢量通过 R_xlen_t 类型建立索引，该类型在64位平台上为64位，而在 int 在32位平台上。
In recent versions of R, vectors are indexed by the R_xlen_t type, which is 64 bits on 64 bits platforms and just int on 32 bit platforms.
到目前为止，Rcpp仍然在任何地方都使用 int 。我鼓励您在其问题列表中请求该功能。这并不难，但是需要有技能，时间和意愿的人系统地参与。 Rcpp11 的开发版本使用正确的类型，也许他们可以将其用作模型。
Rcpp so far still uses int everywhere. I would encourage you to request the feature on their issue list. It is not hard, but needs systematic involvement of someone with skills, time and willingness. The development version of Rcpp11 uses the correct type, perhaps they can use that as a model.
但是请注意，即使R在64位平台上使用64位无符号整数，实际上您也受限于 length ，这就是R会给您的。 R没有可以本地表示的64位整数类型，因此当您要求向量的长度时，您会得到 int 或 double 取决于值。
Note however that even though R uses 64 bit unsigned integers on 64 bit plaforms, you are in fact limited to the range that can be handled by the double type, which is what R will give you if you ask for the length of a vector. R has no 64 bit integer type that it can represent natively, so when you ask for the length of a vector you either get an int or a double depending on the value.
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