R语言 列联表。总说找不到对象。为什么啊。

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R语言 列联表。总说找不到对象。为什么啊。,第1张

可以用：

attach(weightBJ_data)

cor.test(first,second)

#或者

cor.test(weightBJ_data$first,weightBJ_data$second)

#或者

cor.test(weightBJ_data[,1],weightBJ_data[,2])

用过attach(weightBJ_data)之后。

first才能识别，但应该是没有逗号的。

扩展资料：

R语言中的基本运算函数：

1、log(1:3)：对于base未指定，默认为自然对数，取以自然对数为底，分别为1,2,3的对数

2、print(“Hello World!”)：打印

3、abs(x<–8)：取绝对值

4、log(x,base=2)：取对数

5、log(1:3)：对于base未指定，默认为自然对数，取以自然对数为底，分别为1,2,3的对数

6、exp(2)：自然对数e的2次方

Sys.Date( ) returns today's date.

date() returns the current date and time.

# print today's date

today <-Sys.Date()

format(today, format="%B %d %Y")

"June 20 2007"

# convert date info in format 'mm/dd/yyyy'

strDates <- c("01/05/1965", "08/16/1975")

dates <- as.Date(strDates, "%m/%d/%Y")

# convert dates to character data

strDates <- as.character(dates)

--------------------------------------

>as.Date('1915-6-16')

[1] "1915-06-16"

>as.Date('1990/02/17')

[1] "1990-02-17"

>as.Date('1/15/2001',format='%m/%d/%Y')

[1] "2001-01-15"

>as.Date('April 26, 2001',format='%B %d, %Y')

[1] "2001-04-26"

>as.Date('22JUN01',format='%d%b%y') # %y is system-specificuse with caution

[1] "2001-06-22"

>bdays = c(tukey=as.Date('1915-06-16'),fisher=as.Date('1890-02-17'),

+ cramer=as.Date('1893-09-25'), kendall=as.Date('1907-09-06'))

>weekdays(bdays)

tukey fisher cramer kendall

"Wednesday""Monday""Monday""Friday"

>dtimes = c("2002-06-09 12:45:40","2003-01-29 09:30:40",

+"2002-09-04 16:45:40","2002-11-13 20:00:40",

+"2002-07-07 17:30:40")

>dtparts = t(as.data.frame(strsplit(dtimes,' ')))

>row.names(dtparts) = NULL

>thetimes = chron(dates=dtparts[,1],times=dtparts[,2],

+ format=c('y-m-d','h:m:s'))

>thetimes

[1] (02-06-09 12:45:40) (03-01-29 09:30:40) (02-09-04 16:45:40)

[4] (02-11-13 20:00:40) (02-07-07 17:30:40)

>dts = c("2005-10-21 18:47:22","2005-12-24 16:39:58",

+ "2005-10-28 07:30:05 PDT")

>as.POSIXlt(dts)

[1] "2005-10-21 18:47:22" "2005-12-24 16:39:58"

[3] "2005-10-28 07:30:05"

>dts = c(1127056501,1104295502,1129233601,1113547501,

+ 1119826801,1132519502,1125298801,1113289201)

>mydates = dts

>class(mydates) = c('POSIXt','POSIXct')

>mydates

[1] "2005-09-18 08:15:01 PDT" "2004-12-28 20:45:02 PST"

[3] "2005-10-13 13:00:01 PDT" "2005-04-14 23:45:01 PDT"

[5] "2005-06-26 16:00:01 PDT" "2005-11-20 12:45:02 PST"

[7] "2005-08-29 00:00:01 PDT" "2005-04-12 00:00:01 PDT"

>mydate = strptime('16/Oct/2005:07:51:00',format='%d/%b/%Y:%H:%M:%S')

[1] "2005-10-16 07:51:00"

>ISOdate(2005,10,21,18,47,22,tz="PDT")

[1] "2005-10-21 18:47:22 PDT"

>thedate = ISOdate(2005,10,21,18,47,22,tz="PDT")

>format(thedate,'%A, %B %d, %Y %H:%M:%S')

[1] "Friday, October 21, 2005 18:47:22"

>mydate = as.POSIXlt('2005-4-19 7:01:00')

>names(mydate)

[1] "sec" "min" "hour" "mday" "mon" "year"

[7] "wday" "yday" "isdst"

>mydate$mday

[1] 19

将日期字符串作为日期对象处理即可，结果如下：

>max(as.Date("2019/1/7"),as.Date("2019/1/6"),as.Date("2018/1/7"))

[1] "2019-01-07"

>min(as.Date("2019/1/7"),as.Date("2019/1/6"),as.Date("2018/1/7"))

[1] "2018-01-07"