生物信息学生R入门教程–R编程

本教程版权为《糗世界》所有，任何组织或个人不得未经书面许可转载。

在阅读本节前请自测，如果全部都知道正确答案，则可跳过本节。

• 常用函数是否全部掌握（见下表）？
• 请编写一个函数并达到自己的设计要求。
• 为什么R应该尽量避免for循环？
• 什么是引用类(refference class)

常用函数列表

下表是常用函数列表，这里只列出函数名，如果有任何一个函数名称读者感觉陌生的话，请一定使用帮助来查看其内容来填补基础知识的空缺。

# 一切的开始
?, ??, vignette
str

# 帮助
help, ?
help.search
apropos
RSiteSearch
citation
demo
example
vignette

# 环境变量 
ls, exists, rm
getwd, setwd
q
source
install.packages, biocLite
library, require

# 文件与目录
dir
basename, dirname, tools::file_ext
file.path
path.expand, normalizePath
file.choose
file.copy, file.create, file.remove, file.rename, dir.create
file.exists, file.info
tempdir, tempfile
download.file, library(downloader)

# 取值与赋值
=, <-, <<-
%in%, match
$, [, [[, head, tail, subset
with, attach, detach
assign, get

# 逻辑与集合运算 
&, |, !, xor
&&, ||
all.equal, identical
!=, ==, >, >=, <, <=
which 
is.na, is.finite
(is/as).(character/numeric/logical/...)
all, any
intersect, union, setdiff, setequal
sample

# 数学
*, +, -, /, ^, %%, %/%
abs, sign
acos, asin, atan, atan2
sin, cos, tan
ceiling, floor, round, trunc, signif
exp, log, log10, log2, sqrt

max, min, prod, sum
cummax, cummin, cumprod, cumsum, diff
pmax, pmin
range
mean, median, cor, sd, var
rle

# 字符操作
grep, agrep
gsub
strsplit
substr
paste
chartr
nchar
tolower, toupper

# 条件语句
if
for, while
next, break
switch
ifelse

# 函数
function
missing
stop, warning, message
match.arg, dotsMethods
on.exit
return, invisible

# Vectors 和 matrix
c, matrix
# 在类型强制转换时 character > numeric > logical
length, dim, ncol, nrow
cbind, rbind
names, colnames, rownames
t
diag
sweep
as.matrix, data.matrix

# vector相关
c
rep, rep_len
seq, seq_len, seq_along
rev

# Lists & data.frames相关 
list, unlist
data.frame, as.data.frame
split
expand.grid

# Factors 
factor, levels, nlevels
reorder, relevel
cut, findInterval
interaction
options(stringsAsFactors = FALSE)

# Array操作
array
dim
dimnames

# 排序与列表
duplicated, unique
merge
order, rank, quantile
sort
table, ftable

# 排错
traceback
browser
recover
options(error = )
stop, warning, message
tryCatch, try

# 输出
print, cat
message, warning
dput
format
sink, capture.output

# 读写数据
data
count.fields
read.csv, write.csv
read.delim, write.delim
read.fwf
readLines, writeLines
readRDS, saveRDS
load, save
library(foreign)