Question

我正在以在线方式处理时间序列，所以我需要按顺序提取日期（一次一个）。我用过：

dates<- seq(as.Date(today), by="days", length=10)
dates[1]
           [,1]
2016-06-24   NA

我想像在矩阵中那样提取每个元素，例如：

mat<- matrix(c(1,2),ncol=1, nrow=2)
mat[1,1]
[1] 1

如何通过索引或循环获取日期部分，即2016-06-24？

Answer 1

如果我误解了你的问题，请告诉我。这会将它们按顺序排列并将其打印到屏幕上：

dates<- seq(as.Date(Sys.Date()), by="days", length=10)

for(i in 1:length(dates)){
  print(paste("I have extracted the following date:", dates[i]))
}

[1] "I have extracted the following date: 2016-06-25"
[1] "I have extracted the following date: 2016-06-26"
[1] "I have extracted the following date: 2016-06-27"
[1] "I have extracted the following date: 2016-06-28"
[1] "I have extracted the following date: 2016-06-29"
[1] "I have extracted the following date: 2016-06-30"
[1] "I have extracted the following date: 2016-07-01"
[1] "I have extracted the following date: 2016-07-02"
[1] "I have extracted the following date: 2016-07-03"
[1] "I have extracted the following date: 2016-07-04"

Answer 2

使用paste()函数一次打印所有文本并将其与dates对象合并。

  today <- Sys.Date()
  today
  # [1] "2016-06-26"

  dates<- seq(as.Date(today), by="days", length=10)
  dates
  #  [1] "2016-06-26" "2016-06-27" "2016-06-28" "2016-06-29" "2016-06-30"
  #  [6] "2016-07-01" "2016-07-02" "2016-07-03" "2016-07-04" "2016-07-05"

  paste("I have extracted the following date: ",dates)
  # [1] "I have extracted the following date:  2016-06-26"
  # [2] "I have extracted the following date:  2016-06-27"
  # [3] "I have extracted the following date:  2016-06-28"
  # [4] "I have extracted the following date:  2016-06-29"
  # [5] "I have extracted the following date:  2016-06-30"
  # [6] "I have extracted the following date:  2016-07-01"
  # [7] "I have extracted the following date:  2016-07-02"
  # [8] "I have extracted the following date:  2016-07-03"
  # [9] "I have extracted the following date:  2016-07-04"
  #[10] "I have extracted the following date:  2016-07-05"

在R中提取日期

2 个答案: