data.table fread函数 [英] data.table fread function

问题描述

我使用新的 data.table ::: fread 函数（最快的读取函数我在R中使用到目前为止），我得到以下（自我解释）exception：

I am using the new data.table:::fread function (fastest read function I've used in R so far) and I got the following (self explanatory) exception:

R) fread(path)
Erreur dans fread(path) : Coercing integer64 to real needs to be implemented

我的文件（由制表符分隔的csv）确实包含大整数，例如 902160000671352000 。我的问题是，我可以告诉 fread 到＃NOT＃读取第二列（这些怪物int是）

My file (which is a csv separated by tabs) indeed holds big integers like 902160000671352000. My question is then, can I tell fread to #NOT# read the second columns (where those monsters int are)

推荐答案

好问题。还没有，但是你会的。同意所有评论。

Good question. Not yet, but yes you will be able to. Agree with all comments.

TO DO列表位于 readfile.c source 。如果有什么缺失，请让我知道。该列表涵盖允许类型覆盖，实现未实现的强制，并允许跳过列。希望所有将在1.9.0的首次发布。

The TO DO list is at the top of the readfile.c source. If there's anything missing please let me know. That list covers allowing type overrides, implementing the unimplemented coercions and allowing columns to be skipped. Hopefully will all be done for first release in 1.9.0.

fread 目前在v1.8.7在R-Forge的发展。完成后它将作为1.9.0发布到CRAN。 .0表示新功能可能会更改参数名称和行为;即，如果对1.9.1中的 fread 进行后向不可容性更改，则不要感到惊讶。鉴于它的本质，很难想象任何主要会改变，虽然。但是这就是为什么我在R-Forge上公布了它的可用性，以便早日实现这一目标。

fread is currently in v1.8.7 which is in development on R-Forge. When finished it'll be released as 1.9.0 to CRAN. The .0 indicates that new features might possibly change argument names and behaviour; i.e., don't be surprised if backwards incompatabile changes are made to fread in 1.9.1. Given its nature it's hard to imagine anything major will change, though. But that's why I publicised its availability on R-Forge, to get it into the wild early and get things like this right.

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