R_basicfun.Rmd

---
title: "R的常用函数与数据结构"
author: "李峰"
date: "2019年4月"
output:
  html_document: 
    number_sections: yes
    theme: lumen
    toc: yes
    toc_depth: 5
---


---


# 基础函数



## 首先要学习的函数

+ ?   
R中的帮助功能

```{r}
? str
```


+ str   
显示对象内部结构
```{r}
x <- 1:7
str(x)
```


## 重要的操作符

+ %in%, match
+ =, <-, <<-
+ $, [, [[, head, tail, subset
+ with
+ assign, get


## 比较

+ all.equal, identical
+ !=, ==, >, >=, <, <=
+ is.na, complete.cases
+ is.finite



## 基础数学

+ *, +, -, /, ^, %%, %/%
+ 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

## 处理函数的函数

+ function
+ missing
+ on.exit
+ return, invisible

## 逻辑与集合

+ &, |, !, xor
+ all, any
+ intersect, union, setdiff, setequal
+ which


## 向量和矩阵

+ c, matrix
+ length, dim, ncol, nrow
+ cbind, rbind
+ names, colnames, rownames
+ t
+ diag
+ sweep
+ as.matrix, data.matrix



## 构建向量

+ c
+ rep, rep_len
+ seq, seq_len, seq_along
+ rev
+ sample
+ choose, factorial, combn
+ (is/as).(character/numeric/logical/...)

## 列表和数据框

+ list, unlist
+ data.frame, as.data.frame
+ split
+ expand.grid


## 控制流

+ if, &&, || (short circuiting)
+ for, while
+ next, break
+ switch
+ ifelse


## apply函数

+ lapply, sapply, vapply
+ apply
+ tapply
+ replicate




# 常见数据结构

## 日期数据

+ ISOdate, ISOdatetime, strftime, strptime, date
+ difftime
+ julian, months, quarters, weekdays
+ library(lubridate)

## 字符处理

+ grep, agrep
+ gsub
+ strsplit
+ chartr
+ nchar
+ tolower, toupper
+ substr
+ paste
+ trimws
+ library(stringr)


## 因子

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

## 数组处理

+ array
+ dim
+ dimnames
+ aperm
+ library(abind)



# 统计函数


## 排序和制表

+ duplicated, unique
+ merge
+ order, rank, quantile
+ sort
+ table, ftable


## 线性模型

+ fitted, predict, resid, rstandard
+ lm, glm
+ hat, influence.measures
+ logLik, df, deviance
+ formula, ~, I
+ anova, coef, confint, vcov
+ contrasts


## 随机变量

+ (q, p, d, r) * (beta, binom, cauchy, chisq, exp, f, gamma, geom, 
  hyper, lnorm, logis, multinom, nbinom, norm, pois, signrank, t, 
  unif, weibull, wilcox, birthday, tukey)


## 矩阵算法

+ crossprod, tcrossprod
+ eigen, qr, svd
+ %*%, %o%, outer
+ rcond
+ solve