以月为单位计算R中的天数

我在R中有这样的数据帧

cambridgeparking <- read.csv("camparking.csv")

Ticket.Issue.Date   Issue.Time   Location      Violation.Description
January 1, 2014     1:24AM       Green ST      NO PARKING
January 2, 2014     10:45AM      Gore ST       NO STOPPING
January 6, 2014     3:00PM       Franklin ST   HANDICAP RAMP
..                  ..           ..            ..
March 9, 2014       3:29AM       Green ST      NO PARKING
..                  ..           ..            ..
November 10, 2014   9:30PM       Marshall ST   METER PASSED
November 30, 2014   10:20PM      Erie ST       METER PASSED

---

cambridgeparking我们可以从“Ticket.Issue.Date”中提取月份，方法是使用
sub
删除月份后的部分子字符串，然后使用
table
获取每月的计数

table(sub(' .*', '', camparking$Ticket.Issue.Date))

# January    March November 
#   3        1        2 

如果我们只需要“一月”

sum(sub(' .*', '', camparking$Ticket.Issue.Date)=='January')
#[1] 3

数据
露营成功了！！有没有办法提取每个月（例如1月、2月、3月、4月等）的总数然后打印结果？@MichaelCKang第一个选项是
表格
，它可以让您获得所有的月份计数。如果您要连续使用日期和时间，我建议您查看
lubridate
包。处理这类问题非常好。
sum(sub(' .*', '', camparking$Ticket.Issue.Date)=='January')
#[1] 3

camparking <- structure(list(Ticket.Issue.Date = c("January 1, 2014", 
"January 2, 2014", 
"January 6, 2014", "March 9, 2014", "November 10, 2014", 
"November 30, 2014"
), Issue.Time = c("1:24AM", "10:45AM", "3:00PM", "3:29AM", "9:30PM", 
"10:20PM"), Location = c("Green ST", "Gore ST", "Franklin ST", 
"Green ST", "Marshall ST", "Erie ST"), Violation.Description = c("NO PARKING", 
"NO STOPPING", "HANDICAP RAMP", "NO PARKING", "METER PASSED", 
"METER PASSED")), .Names = c("Ticket.Issue.Date", "Issue.Time", 
"Location", "Violation.Description"), class = "data.frame",
 row.names = c(NA, -6L))