转换数据框中的日期列

Question

R版本:3.1.0

已读取以下线程: - 格式化数据框中的日期列 - 将带有日期列的数据框转换为时间序列

关于这个话题的其他几个信息没有任何运气.

我只需要从.csv文件导入一个数据框,我需要索引是Date列指定的日期列.

df <- read.csv(sti, header=TRUE)
df$Date <- as.Date(df$Date, format="%Y%m%d")

(我尝试了其他几种日期格式)

这应该相当简单,但结果是填充了N/As的列,具有错误日期的列和错误消息.

我的csv文件包含Excel日期格式,我尝试更改Windows中的语言设置.

我知道这是日期格式,但我不知道是什么.即使是头部的dput()似乎也没有了.这是一个缩短版本:

structure(list(Date = c("30/12/2013", "27/12/2013", "23/12/2013", 
"20/12/2013", "19/12/2013", "18/12/2013"), MAERSKA = c(11180, 
11150, 10900, 10770, 10670, 10500), WDH = c(527, 522, 515.5, 
515.5, 512, 504.5), VWS = c(160.2, 159.8, 157, 156.6, 156.5, 
153), TRYG = c(524.5, 523, 520.5, 519, 504, 484), TOP = c(142.8, 
142.5, 141.9, 141.5, 139.9, 136.5), TDC = c(52.6, 52.7, 52.45, 
51.95, 51.65, 51.85), Pandora = c(294, 301.2, 304, 300.3, 296.1, 
293.1), NOVOB = c(198.8, 197.2, 195.1, 196.3, 195.6, 190.7), 
    Nordea = c(72.05, 71.35, 70.6, 70.1, 68.65, 67.8), COLOB = c(359, 
    358.3, 353.4, 353.2, 350.2, 342), CHR = c(215.4, 215.7, 212.3, 
    209.1, 206.3, 204.2), CARLB = c(600, 596, 586.5, 586, 584, 
    573), MAERSKB = c(11770, 11740, 11510, 11310, 11210, 11070
    ), JYSKE = c(292.5, 288, 284.4, 282.8, 276.9, 275.7), GN = c(133.2, 
    132.3, 130.5, 129, 127.8, 126.2), GENMAB = c(212, 214.9, 
    217.4, 222.5, 221.6, 216.7), FLS = c(296.1, 290.3, 280.3, 
    278.1, 273.6, 267.1), DSV = c(177.8, 178.2, 176.8, 174, 171.2, 
    169.3), DANSKE = c(124.4, 124.3, 124.3, 123.7, 121, 120.3
    ), NOVOZYMESB = c(228.9, 229.9, 228.5, 230.4, 219.9, 215.6
    )), .Names = c("Date", "MAERSKA", "WDH", "VWS", "TRYG", "TOP", 
"TDC", "Pandora", "NOVOB", "Nordea", "COLOB", "CHR", "CARLB", 
"MAERSKB", "JYSKE", "GN", "GENMAB", "FLS", "DSV", "DANSKE", "NOVOZYMESB"
), row.names = c(NA, 6L), class = "data.frame")

附加信息:

> sessionInfo()
R version 3.1.0 (2014-04-10)
Platform: x86_64-w64-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=English_United Kingdom.1252 
[2] LC_CTYPE=English_United Kingdom.1252   
[3] LC_MONETARY=English_United Kingdom.1252
[4] LC_NUMERIC=C                           
[5] LC_TIME=English_United Kingdom.1252    

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

我希望有人知道可能导致问题的原因.稍后我需要将数据帧转换为zoo对象,因为PerformanceAnalytics包需要它作为输入.

Answer 1

使用您在上面发布的数据,Date列是一个字符.由于您的日期看起来像"30/12/2013"​​格式应该是"%d /%m /%Y"而不是"%Y%m%d".使格式正确以进行转换非常重要.因此你应该能够做到

df$Date <- as.Date(df$Date, format="%d/%m/%Y")

有了样本数据,

> class(df$Date)=="Date"
[1] TRUE
> sum(is.na(df$Date))==0
[1] TRUE

所以一切都很好看.