L1code

1 赋值符

1.1 左箭头<-

# 赋值符：左箭头<- 
# 快捷键Windows系统：Alt + - 
# 快捷键Mac系统：Option + -

a <- 1
a

[1] 1

1.2 等号=

# = 也可以赋值，但是不推荐使用
# = 用于给函数的参数赋值

round(pi, digits = 2)

[1] 3.14

2 常用函数

2.1 数学运算

# 加法
2+3

[1] 5

# 减法
2-3

[1] -1

# 乘法
2*3

[1] 6

# 除法
9 / 2

[1] 4.5

# 次方
2 ^ 3

[1] 8

# 取余
9 %% 2

[1] 1

# 整除
9 %/% 2

[1] 4

# 自然对数
log(2)

[1] 0.6931472

# 以10为底的对数
log10(2)

[1] 0.30103

# 平方根
sqrt(2)

[1] 1.414214

# 绝对值
abs(-2)

[1] 2

# 向上取整
ceiling(2.1)

[1] 3

# 向下取整
floor(2.1)

[1] 2

# 四舍五入
round(2.1)

[1] 2

# 圆周率
pi

[1] 3.141593

# 圆周率保留6位小数
round(pi,6)

[1] 3.141593

2.2 随机数函数

# 生成100个在0至1之间均匀分布的随机数
runif(100)

# 生成100个服从标准正态分布的随机数
rnorm(100)

# 生成100个服从泊松分布的随机数
rpois(100,lambda=2)

2.3 统计函数

x <- rnorm(1000, mean = 10, sd = 2)


mean(x)

[1] 10.11319

median(x)

[1] 10.16237

sd(x)

[1] 2.006202

var(x)

[1] 4.024846

range(x)

[1]  4.160856 17.511642

quantile(x)

       0%       25%       50%       75%      100% 
 4.160856  8.813064 10.162370 11.443974 17.511642 

summary(x)

   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
  4.161   8.813  10.162  10.113  11.444  17.512 

2.4 关系运算符

# 等于
2 == 3

[1] FALSE

# 不等于
2 != 3

[1] TRUE

# 大于
2 > 3

[1] FALSE

# 小于
2 < 3

[1] TRUE

# 大于等于
2 >= 3

[1] FALSE

# 小于等于
2 <= 3

[1] TRUE

3 调用R自带数据集

data(mtcars)
mtcars

                     mpg cyl  disp  hp drat    wt  qsec vs am gear carb
Mazda RX4           21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
Mazda RX4 Wag       21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
Datsun 710          22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
Hornet 4 Drive      21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
Hornet Sportabout   18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2
Valiant             18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1
Duster 360          14.3   8 360.0 245 3.21 3.570 15.84  0  0    3    4
Merc 240D           24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2
Merc 230            22.8   4 140.8  95 3.92 3.150 22.90  1  0    4    2
Merc 280            19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4
Merc 280C           17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4
Merc 450SE          16.4   8 275.8 180 3.07 4.070 17.40  0  0    3    3
Merc 450SL          17.3   8 275.8 180 3.07 3.730 17.60  0  0    3    3
Merc 450SLC         15.2   8 275.8 180 3.07 3.780 18.00  0  0    3    3
Cadillac Fleetwood  10.4   8 472.0 205 2.93 5.250 17.98  0  0    3    4
Lincoln Continental 10.4   8 460.0 215 3.00 5.424 17.82  0  0    3    4
Chrysler Imperial   14.7   8 440.0 230 3.23 5.345 17.42  0  0    3    4
Fiat 128            32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1
Honda Civic         30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2
Toyota Corolla      33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1
Toyota Corona       21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1
Dodge Challenger    15.5   8 318.0 150 2.76 3.520 16.87  0  0    3    2
AMC Javelin         15.2   8 304.0 150 3.15 3.435 17.30  0  0    3    2
Camaro Z28          13.3   8 350.0 245 3.73 3.840 15.41  0  0    3    4
Pontiac Firebird    19.2   8 400.0 175 3.08 3.845 17.05  0  0    3    2
Fiat X1-9           27.3   4  79.0  66 4.08 1.935 18.90  1  1    4    1
Porsche 914-2       26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2
Lotus Europa        30.4   4  95.1 113 3.77 1.513 16.90  1  1    5    2
Ford Pantera L      15.8   8 351.0 264 4.22 3.170 14.50  0  1    5    4
Ferrari Dino        19.7   6 145.0 175 3.62 2.770 15.50  0  1    5    6
Maserati Bora       15.0   8 301.0 335 3.54 3.570 14.60  0  1    5    8
Volvo 142E          21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2

# 报告mtcars描述性统计量
summary(mtcars)

      mpg             cyl             disp             hp       
 Min.   :10.40   Min.   :4.000   Min.   : 71.1   Min.   : 52.0  
 1st Qu.:15.43   1st Qu.:4.000   1st Qu.:120.8   1st Qu.: 96.5  
 Median :19.20   Median :6.000   Median :196.3   Median :123.0  
 Mean   :20.09   Mean   :6.188   Mean   :230.7   Mean   :146.7  
 3rd Qu.:22.80   3rd Qu.:8.000   3rd Qu.:326.0   3rd Qu.:180.0  
 Max.   :33.90   Max.   :8.000   Max.   :472.0   Max.   :335.0  
      drat             wt             qsec             vs        
 Min.   :2.760   Min.   :1.513   Min.   :14.50   Min.   :0.0000  
 1st Qu.:3.080   1st Qu.:2.581   1st Qu.:16.89   1st Qu.:0.0000  
 Median :3.695   Median :3.325   Median :17.71   Median :0.0000  
 Mean   :3.597   Mean   :3.217   Mean   :17.85   Mean   :0.4375  
 3rd Qu.:3.920   3rd Qu.:3.610   3rd Qu.:18.90   3rd Qu.:1.0000  
 Max.   :4.930   Max.   :5.424   Max.   :22.90   Max.   :1.0000  
       am              gear            carb      
 Min.   :0.0000   Min.   :3.000   Min.   :1.000  
 1st Qu.:0.0000   1st Qu.:3.000   1st Qu.:2.000  
 Median :0.0000   Median :4.000   Median :2.000  
 Mean   :0.4062   Mean   :3.688   Mean   :2.812  
 3rd Qu.:1.0000   3rd Qu.:4.000   3rd Qu.:4.000  
 Max.   :1.0000   Max.   :5.000   Max.   :8.000  

#查看R自带的数据集
library(help = "datasets")

4 绘图

# 箱线图
boxplot(mtcars$mpg)

# 箱线图自定义标题，边框，填充颜色，水平放置
boxplot(mtcars$mpg, main = "mpg",
        border = "gray", col = "cyan", horizontal = TRUE)

# 直方图

hist(mtcars$mpg)

# 直方图自定义标题，边框，填充颜色，组距

hist(mtcars$mpg, main = "mpg", breaks = seq(10,34,3),
     border = "black",col = "cyan", xlim = c(10,35), ylim = c(0,10))

# 散点图
plot(mtcars$mpg,mtcars$wt)

# 折线图
plot(mtcars$mpg,type="l")

5 包的安装和加载

5.1 从CRAN安装包

# 安装包
# install.packages("psych")
# 加载包
library(psych)
describe(mtcars$mpg)

   vars  n  mean   sd median trimmed  mad  min  max range skew kurtosis   se
X1    1 32 20.09 6.03   19.2    19.7 5.41 10.4 33.9  23.5 0.61    -0.37 1.07

psych::describe(mtcars$mpg)

   vars  n  mean   sd median trimmed  mad  min  max range skew kurtosis   se
X1    1 32 20.09 6.03   19.2    19.7 5.41 10.4 33.9  23.5 0.61    -0.37 1.07

psych::describe(mtcars)

     vars  n   mean     sd median trimmed    mad   min    max  range  skew
mpg     1 32  20.09   6.03  19.20   19.70   5.41 10.40  33.90  23.50  0.61
cyl     2 32   6.19   1.79   6.00    6.23   2.97  4.00   8.00   4.00 -0.17
disp    3 32 230.72 123.94 196.30  222.52 140.48 71.10 472.00 400.90  0.38
hp      4 32 146.69  68.56 123.00  141.19  77.10 52.00 335.00 283.00  0.73
drat    5 32   3.60   0.53   3.70    3.58   0.70  2.76   4.93   2.17  0.27
wt      6 32   3.22   0.98   3.33    3.15   0.77  1.51   5.42   3.91  0.42
qsec    7 32  17.85   1.79  17.71   17.83   1.42 14.50  22.90   8.40  0.37
vs      8 32   0.44   0.50   0.00    0.42   0.00  0.00   1.00   1.00  0.24
am      9 32   0.41   0.50   0.00    0.38   0.00  0.00   1.00   1.00  0.36
gear   10 32   3.69   0.74   4.00    3.62   1.48  3.00   5.00   2.00  0.53
carb   11 32   2.81   1.62   2.00    2.65   1.48  1.00   8.00   7.00  1.05
     kurtosis    se
mpg     -0.37  1.07
cyl     -1.76  0.32
disp    -1.21 21.91
hp      -0.14 12.12
drat    -0.71  0.09
wt      -0.02  0.17
qsec     0.34  0.32
vs      -2.00  0.09
am      -1.92  0.09
gear    -1.07  0.13
carb     1.26  0.29

5.2 查看包的信息

# 查看包的信息
sessionInfo()

R version 4.4.2 (2024-10-31)
Platform: aarch64-apple-darwin20
Running under: macOS Sequoia 15.1.1

Matrix products: default
BLAS:   /Library/Frameworks/R.framework/Versions/4.4-arm64/Resources/lib/libRblas.0.dylib 
LAPACK: /Library/Frameworks/R.framework/Versions/4.4-arm64/Resources/lib/libRlapack.dylib;  LAPACK version 3.12.0

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

time zone: Asia/Shanghai
tzcode source: internal

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] psych_2.4.3

loaded via a namespace (and not attached):
 [1] digest_0.6.35     fastmap_1.2.0     xfun_0.50         lattice_0.22-6   
 [5] knitr_1.46        parallel_4.4.2    htmltools_0.5.8.1 rmarkdown_2.26   
 [9] cli_3.6.2         grid_4.4.2        mnormt_2.1.1      compiler_4.4.2   
[13] rstudioapi_0.16.0 tools_4.4.2       nlme_3.1-166      evaluate_0.23    
[17] yaml_2.3.8        rlang_1.1.4       jsonlite_1.8.8    htmlwidgets_1.6.4

# 查看包的版本
packageVersion("psych")

[1] '2.4.3'

# 查看包的作者
packageDescription("psych")$Author

[1] "William Revelle [aut, cre] (<https://orcid.org/0000-0003-4880-9610>)"

# 显示R包存储在计算机上的位置
.libPaths()

[1] "/Library/Frameworks/R.framework/Versions/4.4-arm64/Resources/library"

# 查看已安装的包
library()

# 查看已加载的包
search()

 [1] ".GlobalEnv"        "package:psych"     "package:stats"    
 [4] "package:graphics"  "package:grDevices" "package:utils"    
 [7] "package:datasets"  "package:methods"   "Autoloads"        
[10] "package:base"     

5.3 加载包

#频繁使用psych
library(psych) 
describe(mtcars$mpg)

   vars  n  mean   sd median trimmed  mad  min  max range skew kurtosis   se
X1    1 32 20.09 6.03   19.2    19.7 5.41 10.4 33.9  23.5 0.61    -0.37 1.07

describeBy(mtcars$mpg, group = mtcars$cyl)

 Descriptive statistics by group 
group: 4
   vars  n  mean   sd median trimmed  mad  min  max range skew kurtosis   se
X1    1 11 26.66 4.51     26   26.44 6.52 21.4 33.9  12.5 0.26    -1.65 1.36
------------------------------------------------------------ 
group: 6
   vars n  mean   sd median trimmed  mad  min  max range  skew kurtosis   se
X1    1 7 19.74 1.45   19.7   19.74 1.93 17.8 21.4   3.6 -0.16    -1.91 0.55
------------------------------------------------------------ 
group: 8
   vars  n mean   sd median trimmed  mad  min  max range  skew kurtosis   se
X1    1 14 15.1 2.56   15.2   15.15 1.56 10.4 19.2   8.8 -0.36    -0.57 0.68

#偶尔使用psych
psych::describe(mtcars$mpg)

   vars  n  mean   sd median trimmed  mad  min  max range skew kurtosis   se
X1    1 32 20.09 6.03   19.2    19.7 5.41 10.4 33.9  23.5 0.61    -0.37 1.07

psych::describeBy(mtcars$mpg, group = mtcars$cyl)

 Descriptive statistics by group 
group: 4
   vars  n  mean   sd median trimmed  mad  min  max range skew kurtosis   se
X1    1 11 26.66 4.51     26   26.44 6.52 21.4 33.9  12.5 0.26    -1.65 1.36
------------------------------------------------------------ 
group: 6
   vars n  mean   sd median trimmed  mad  min  max range  skew kurtosis   se
X1    1 7 19.74 1.45   19.7   19.74 1.93 17.8 21.4   3.6 -0.16    -1.91 0.55
------------------------------------------------------------ 
group: 8
   vars  n mean   sd median trimmed  mad  min  max range  skew kurtosis   se
X1    1 14 15.1 2.56   15.2   15.15 1.56 10.4 19.2   8.8 -0.36    -0.57 0.68

6 查看帮助文档

# 查看函数帮助文档
?describe

# 查看包帮助文档
?psych

# 查看数据集帮助文档
?mtcars

7 将数据框导出为Excel文件

# install.packages("writexl")
library(writexl)
# 导出的Exel文件放在项目/工作路径中，否则需要写出完整路径
write_xlsx(mtcars, "mtcars.xlsx")

8 将图形导出

# install.packages("export")
library(export)
# 自定义散点图点的颜色、边框、形状、大小、标题
plot(mtcars$mpg, mtcars$wt, col = "red", pch = 19,cex = 2,main = "mpg")

# 导出的图形放在项目/工作路径中，否则需要写出完整路径
# png("mtcars.png")