数据表错误找不到函数“”。

本文介绍了数据表错误找不到函数“”。的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在尝试运行以下代码。每当我尝试运行代码时，都会出现以下错误： eval（expr，envir，enclos）中的错误：找不到函数。 如何我修理它？有人可以帮忙吗？

I am trying to run the following piece of code. Whenever I try to run the code I get the following error: Error in eval(expr, envir, enclos) : could not find function "." How can I fix it? Could someone help?

data(mtcars) library(data.table) mtcarsDT <- data.table(mtcars) mtcarsDT[ mpg > 20, .(AvgHP = mean(hp), "MinWT(kg)" = min(wt * 453.6)), # wt lbs by = .(cyl, under5gears = gear < 5) ]

这是会话信息

> sessionInfo() R version 3.1.2 (2014-10-31) Platform: x86_64-apple-darwin10.8.0 (64-bit) locale: [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8 attached base packages: [1] stats graphics grDevices utils datasets methods base other attached packages: [1] data.table_1.9.2 loaded via a namespace (and not attached): [1] digest_0.6.8 htmltools_0.2.6 plyr_1.8.1 Rcpp_0.11.3 reshape2_1.4.1 rmarkdown_0.3.3 stringr_0.6.2 [8] tools_3.1.2

推荐答案

显然，我2.5年前提供的说明仍然适用于使用过时版本的用户假设您已安装Xcode和命令行工具，则首先需要a）重新启动R（不加载任何版本的data.table。，reshape2和dplyr），或b）删除所有已加载的命名空间。可能与测试加载能力冲突新软件包：

Apparently the instructions I offered 2.5 years ago are still current for people using out-of-date versions of Mac R. Assuming you have Xcode and the Command Line Tools installed, you need to first either a) restart R (without loading any of the versions of data.table., reshape2, and dplyr), or b) remove any loaded Namespaces that might conflict with the ability to test-load the new packages:

unloadNamespace('data.table') unloadNamespace('reshape2') unloadNamespace('plyr')

然后从源代码构建：

install.packages("data.table", type="source", dependencies=TRUE)

在安装二进制软件包时可能无法从源代码进行构建的原因是前一种策略可以使您更好地检查版本依赖性。

The reason that building from source might work when installing a binary package might not is that the former strategy gets you better checking for version dependencies.