setwd("C://path//to//my//prefered//working//directory")
library("ggplot2")
library("RMySQL")
library("foreign")
answer <- readline("What database would you like to connect to? ")
con <- dbConnect(MySQL(),user="root",password="mypass", dbname=answer)

我用mysql数据库做了很多工作，所以马上连接是天赐良机。我只希望有一种方法可以列出可用的数据库，这样我就不必记住所有不同的名称。

这是我的。没什么太创新的。为什么要选择特定的选项:

I went with setting a default for stringsAsFactors because I find it extremely draining to pass it as an argument each time I read a CSV in. That said, it has already caused me some minor vexation when using code written on my usual computer on a computer which did not have my .Rprofile. I'm keeping it, though, as the troubles it has caused pale in comparison to the troubles not having it set everyday used to cause. If you don't load the utils package before options(error=recover), it cannot find recover when placed inside an interactive() block. I used .db for my dropbox setting rather than options(dropbox=...) because I use it all the time inside file.path and it saves much typing. The leading . keeps it from appearing with ls().

话不多说:

if(interactive()) {
    options(stringsAsFactors=FALSE)
    options(max.print=50)
    options(repos="http://cran.mirrors.hoobly.com")
}

.db <- "~/Dropbox"
# `=` <- function(...) stop("Assignment by = disabled, use <- instead")
options(BingMapsKey="blahblahblah") # Used by taRifx.geo::geocode()

.First <- function() {
    if(interactive()) {
        require(functional)
        require(taRifx)
        require(taRifx.geo)
        require(ggplot2)
        require(foreign)
        require(R.utils)
        require(stringr)
        require(reshape2)
        require(devtools)
        require(codetools)
        require(testthat)
        require(utils)
        options(error=recover)
    }
}

我喜欢保存我的R命令历史，并在每次运行R命令时都可用:

在shell或.bashrc中:

export R_HISTFILE=~/.Rhistory

在.Rprofile:

.Last <- function() {
        if (!any(commandArgs()=='--no-readline') && interactive()){
                require(utils)
                try(savehistory(Sys.getenv("R_HISTFILE")))
        }
}

sink(file = 'R.log', split=T)

options(scipen=5)

.ls.objects <- function (pos = 1, pattern, order.by = "Size", decreasing=TRUE, head =     TRUE, n = 10) {
  # based on postings by Petr Pikal and David Hinds to the r-help list in 2004
  # modified by: Dirk Eddelbuettel (http://stackoverflow.com/questions/1358003/tricks-to-    manage-the-available-memory-in-an-r-session) 
  # I then gave it a few tweaks (show size as megabytes and use defaults that I like)
  # a data frame of the objects and their associated storage needs.
  napply <- function(names, fn) sapply(names, function(x)
          fn(get(x, pos = pos)))
  names <- ls(pos = pos, pattern = pattern)
  obj.class <- napply(names, function(x) as.character(class(x))[1])
  obj.mode <- napply(names, mode)
  obj.type <- ifelse(is.na(obj.class), obj.mode, obj.class)
  obj.size <- napply(names, object.size) / 10^6 # megabytes
  obj.dim <- t(napply(names, function(x)
            as.numeric(dim(x))[1:2]))
  vec <- is.na(obj.dim)[, 1] & (obj.type != "function")
  obj.dim[vec, 1] <- napply(names, length)[vec]
  out <- data.frame(obj.type, obj.size, obj.dim)
  names(out) <- c("Type", "Size", "Rows", "Columns")
  out <- out[order(out[[order.by]], decreasing=decreasing), ]
  if (head)
    out <- head(out, n)
  out
}

下面是我发现的两个方便使用窗口的函数。

第一个将\s转换为/。

.repath <- function() {
   cat('Paste windows file path and hit RETURN twice')
   x <- scan(what = "")
   xa <- gsub('\\\\', '/', x)
   writeClipboard(paste(xa, collapse=" "))
   cat('Here\'s your de-windowsified path. (It\'s also on the clipboard.)\n', xa, '\n')
 }

第二个选项在一个新的资源管理器窗口中打开工作目录。

getw <- function() {
    suppressWarnings(shell(paste("explorer",  gsub('/', '\\\\', getwd()))))
}

options(stringsAsFactors=FALSE)

虽然我的. r配置文件中没有这个，因为它可能会破坏我的合作者的代码，但我希望它是默认的。为什么?

1)字符向量使用更少的内存(但只是很少);

2)更重要的是，我们可以避免这样的问题:

> x <- factor(c("a","b","c"))
> x
[1] a b c
Levels: a b c
> x <- c(x, "d")
> x
[1] "1" "2" "3" "d"

and

> x <- factor(c("a","b","c"))
> x[1:2] <- c("c", "d")
Warning message:
In `[<-.factor`(`*tmp*`, 1:2, value = c("c", "d")) :
  invalid factor level, NAs generated

因子在你需要的时候很有用(比如在图中实现排序)，但大多数时候都很麻烦。