轉換因子迄今爲止R中

Question

我有這樣的數據集，並試圖轉換爲日期，這樣我可以列爲圖表：

dput(y) 
structure(c(23L, 17L, 41L, 1L, 47L, 35L, 29L, 7L, 63L, 58L, 53L, 
12L, 24L, 18L, 42L, 2L, 48L, 36L, 30L, 8L, 64L, 59L, 54L, 13L, 
25L, 19L, 43L, 3L, 49L, 37L, 31L, 9L, 65L, 60L, 55L, 14L, 26L, 
20L, 44L, 4L, 50L, 38L, 32L, 10L, 66L, 61L, 56L, 15L, 27L, 21L, 
45L, 5L, 51L, 39L, 33L, 11L, 67L, 62L, 57L, 16L, 28L, 22L, 46L, 
6L, 52L, 40L, 34L), .Label = c("APR-07", "APR-08", "APR-09", 
"APR-10", "APR-11", "APR-12", "AUG-07", "AUG-08", "AUG-09", "AUG-10", 
"AUG-11", "DEC-07", "DEC-08", "DEC-09", "DEC-10", "DEC-11", "FEB-07", 
"FEB-08", "FEB-09", "FEB-10", "FEB-11", "FEB-12", "JAN-07", "JAN-08", 
"JAN-09", "JAN-10", "JAN-11", "JAN-12", "JUL-07", "JUL-08", "JUL-09", 
"JUL-10", "JUL-11", "JUL-12", "JUN-07", "JUN-08", "JUN-09", "JUN-10", 
"JUN-11", "JUN-12", "MAR-07", "MAR-08", "MAR-09", "MAR-10", "MAR-11", 
"MAR-12", "MAY-07", "MAY-08", "MAY-09", "MAY-10", "May-11", "MAY-12", 
"NOV-07", "NOV-08", "NOV-09", "NOV-10", "NOV-11", "OCT-07", "OCT-08", 
"OCT-09", "OCT-10", "OCT-11", "SEP-07", "SEP-08", "SEP-09", "SEP-10", 
"SEP-11"), class = "factor") 

我試圖

y1 <- strptime(y, format = "%b-%y") 

Y1讓所有NA，任何想法？

Answer 1

你需要一天的時間，將其轉換爲一個日期：

##Make each date the first of the month 
strptime(paste("1", as.character(y)), format="%d %b-%y") 

Answer 2

如果你將時間序列上月規模regualr基礎上開展工作，你可能也想看看動物園包，其中作爲不需要添加「每月第一天價值」的「年度日曆」課程。它有許多相關的繪圖和計算方法。廣泛使用的'xts'包基於'動物園'結構。

require(zoo) 
zym <- as.yearmon(as.character(y), "%b-%y") 
str(zym) 
#Class 'yearmon' num [1:67] 2007 2007 2007 2007 2007 ... 
head(zym) 
#[1] "Jan 2007" "Feb 2007" "Mar 2007" "Apr 2007" "May 2007" "Jun 2007" 
format(head(zym), "%b %y") 
#[1] "Jan 07" "Feb 07" "Mar 07" "Apr 07" "May 07" "Jun 07"