sessionInfo() 查看R中载入的包和版本

writeLines(capture.output(sessionInfo()), "sessionInfo.txt")

 

sink("sessionInfo.txt")
sessionInfo()
sink()

 

data.frame 动态确定列名称

 

var <- "mpg"

#Doesn't work
mtcars$var
#These both work, but note that what they return is different
# the first is a vector, the second is a data.frame
mtcars[[var]]
mtcars[var]

 

 

 

data.frame 列命名

Use the colnames() function:

R> X <- data.frame(bad=1:3, worse=rnorm(3))
R> X
  bad     worse
1   1 -2.440467
2   2  1.320113
3   3 -0.306639
R> colnames(X) <- c("good", "better")
R> X
  good    better
1    1 -2.440467
2    2  1.320113
3    3 -0.306639

You can also subset:

R> colnames(X)[2] <- "superduper"

seq(from = 1, to = 1, by = ((to - from)/(length.out - 1)),
    length.out = NULL, along.with = NULL, ...)

举例----------Examples----------
seq(0, 1, length.out=11)
seq(stats::rnorm(20)) # 
seq(1, 9, by = 2)     # 
seq(1, 9, by = pi)    # 
seq(1, 6, by = 3)
seq(1.575, 5.125, by=0.05)
seq(17) # same as 1:17, or even better seq_len(17)

 

Loops

The most commonly used loop structures in R are for, whileand applyloops. Less common are repeat loops. The break function is used to break out of loops, and next

for(variable in sequence) { 
    statements

}
while(condition) statements
apply(X, MARGIN, FUN, ARGs)

 

保存为Tab分隔的txt文件：

write.table(y, file = paste("Day",a, " ",k, ".txt", sep=""), sep = "\t",row.names=FALSE)

data.frame 添加一行：
First, we create a one-row data frame with the new data:

> newRow <- data.frame(city="West Dundee", county="Kane", state="IL", pop=5428)

Next, we use the rbind function to append that one-row data frame to our existing data frame:

> suburbs <- rbind(suburbs, newRow)

 

data.frame 添加一列：

my.dataframe$new.col <- a.vector
my.dataframe[,"new.col"]<- a.vector
my.dataframe["new.col"]<- a.vector
df <-(b =(6),=(6))
cbind(a =0,)

 

data <- read.table(header=TRUE, text='
 id weight
  1     20
  2     27
  3     24
')



# Ways to add a column
data$size      <- c("small", "large", "medium")
data[["size"]] <- c("small", "large", "medium")
data[,"size"]  <- c("small", "large", "medium")
data$size      <- 0   # Use the same value (0) for all rows


# Ways to remove the column
data$size      <- NULL
data[["size"]] <- NULL
data[,"size"]  <- NULL
data[[3]]      <- NULL
data[,3]       <- NULL
data           <- subset(data, select=-size)

options(stringsAsFactors=FALSE)

A simple function to remove leading and trailing whitespace:

trim <- function( x ) {
  gsub("(^[[:space:]]+|[[:space:]]+$)", "", x)
}

Usage:

> text = "   foo bar  baz 3 "
> trim(text)
[1] "foo bar  baz 3"


在R中合并某一数据框的两列数据
需要解决的问题，需要将某一个数据框的两列值合并为一列。
在R中合并某一数据框的两列数据
浏览示例数据
> mtcars
安装tidyr包，之后加载tidyr包
> library(tidyr)
执行命令
> tidyr::unite(mtcars, "vs_am", vs, am)
将 vs 和 am 两列数据合并后，原数据列被删除了（如果想保留原数据列则通过 remove = FALSE 参数控制），新增了 vs_am 列，得到的结果如下。
在R中合并某一数据框的两列数据
个性化合并
如果在合并时想自定义连接符，可以通过参数 sep 控制，运行
> unite(mtcars, "vs_am", vs, am, sep = "ZSF", remove = FALSE)
得到的结果如下，新增 vs_am 列，连接符为 ZSF，原数据列 vs 和 am 得以保存。