修复R中的日期格式

Question

我在R中有三个数据表。每个数据表都有一个日期列。表格为dat <- structure(list(Design.ID = c("KCLRI7-00VU-INSGN1", "KPBK4K-00VU-INSGN1", "KGLGI7-00VU-FETTI1", "KUWB08-00VU-INSGN1", "KUWB08-00VU-INSGN1", "KGLGI7-00VU-FETTI1", "KPBK4K-00VU-INSGN1", "KCLRI7-00VU-INSGN1", "KBAMI7-00VU-INSGN1", "KCLRI7-0FLA-WAVE01", "K510WL-0WEB-PRIME1", "K110MS-0WEB-PRIME1", "KCLRI6-0GON-INSGN1"), Glados.SKU = c("", "", "", "", "", "", "", "", "", "", "K510WL-0WEB-PRIME1", "K110MS-0WEB-PRIME1", "KCLRI6-0GON-INSGN1;KCLRI7-0GON-INSGN1;KCLR7X-0GON-INSGN1;KCLR6X-0GON-INSGN1" )), .Names = c("Design.ID", "Glados.SKU"), row.names = c(NA, -13L), class = "data.frame") 。它们的格式如下：

vix_data,gold_ohlc_data,btc_ohlc_data

如何更改head(vix_data$Date) [1] 1/2/04 1/5/04 1/6/04 1/7/04 1/8/04 1/9/04 3435 Levels: 1/10/05 1/10/06 1/10/07 1/10/08 1/10/11 ... 9/9/16 head(gold_ohlc_data$date) [1] 8/23/17 8/22/17 8/21/17 8/18/17 8/17/17 8/16/17 2519 Levels: 1/10/08 1/10/11 1/10/12 1/10/13 1/10/14 ... 9/9/16 head(btc_ohlc_data$Date) [1] "2017-08-23" "2017-08-22" "2017-08-21" "2017-08-20" "2017-08-19" [6] "2017-08-18" 和vix_data表格中的日期列以匹配gold_ohlc_data格式？我尝试了几种方法，例如使用btc_ohlc_data来转换每一列 - 但这通常会混淆值并插入很多N / A

Answer 1

选项是使用包lubridate中的函数。用户需要知道哪一天是哪一天，哪一个月是选择要使用的正确功能，例如dmy或mdy

# Load package
library(lubridate)

# Create example string
date1 <- c("1/2/04", "1/5/04", "1/6/04", "1/7/04", "1/8/04", "1/9/04")
date2 <- c("8/23/17", "8/22/17", "8/21/17", "8/18/17", "8/17/17", "8/16/17")

# Convert to date class
dmy(date1)
# [1] "2004-02-01" "2004-05-01" "2004-06-01" "2004-07-01" "2004-08-01" "2004-09-01"
mdy(date1)
# [1] "2004-01-02" "2004-01-05" "2004-01-06" "2004-01-07" "2004-01-08" "2004-01-09"
mdy(date2)
# [1] "2017-08-23" "2017-08-22" "2017-08-21" "2017-08-18" "2017-08-17" "2017-08-16"

Answer 2

查看包lubridate。 lubridate::dmy()和ymd()应处理此问题。

Answer 3

看起来您的数据是作为因素读入的，因此首先您必须将它们更改为字符。然后，您可以将其转换为日期并指定输入格式，其中%m代表数字月份，%d代表日期，%y代表2位数年份。

x <- c('1/2/04', '1/5/04', '1/6/04', '1/7/04', '1/8/04', '1/9/04')
y <- as.Date(x, format = "%m/%d/%y")
y
[1] "2004-01-02" "2004-01-05" "2004-01-06" "2004-01-07" "2004-01-08"
[6] "2004-01-09"

Answer 4

您确定要正确指定while (mycursor.moveToNext) { String mytext = mycursor.getString(mycursor.getColumnIndex("mycolumn")); mytextView.setText(mytext); } mycursor.close(); 吗？例如，您有as.Date而不是%y吗？

我做了以下工作并且有效：

%Y