Question

我有一个问题，我一直在工作。我有一个日期数据集（以数据框格式），我需要搜索并查找每个月的最后一天并将它们放入新的数据框中。下一栏中还有一个与之相关的值。下面是日期的样本。

   [1] "2015-05-21" "2015-05-20" "2015-05-19" "2015-05-18" "2015-05-15" "2015-05-14"
   [7] "2015-05-13" "2015-05-12" "2015-05-11" "2015-05-08" "2015-05-07" "2015-05-06"
  [13] "2015-05-05" "2015-05-04" "2015-05-01" "2015-04-30" "2015-04-29" "2015-04-28"
  [19] "2015-04-27" "2015-04-24" "2015-04-23" "2015-04-22" "2015-04-21" "2015-04-20"
  [25] "2015-04-17" "2015-04-16" "2015-04-15" "2015-04-14" "2015-04-13" "2015-04-10"
  [31] "2015-04-09" "2015-04-08" "2015-04-07" "2015-04-06" "2015-04-02" "2015-04-01"
  [37] "2015-03-31" "2015-03-30" "2015-03-27" "2015-03-26" "2015-03-25" "2015-03-24"
  [43] "2015-03-23" "2015-03-20" "2015-03-19" "2015-03-18" "2015-03-17" "2015-03-16"
  [49] "2015-03-13" "2015-03-12" "2015-03-11" "2015-03-10" "2015-03-09" "2015-03-06"
  [55] "2015-03-05" "2015-03-04" "2015-03-03" "2015-03-02" "2015-02-27" "2015-02-26"
  [61] "2015-02-25" "2015-02-24" "2015-02-23" "2015-02-20" "2015-02-19" "2015-02-18"
  [67] "2015-02-17" "2015-02-13" "2015-02-12" "2015-02-11" "2015-02-10" "2015-02-09"
  [73] "2015-02-06" "2015-02-05" "2015-02-04" "2015-02-03" "2015-02-02" "2015-01-30"
  [79] "2015-01-29" "2015-01-28" "2015-01-27" "2015-01-26" "2015-01-23" "2015-01-22"
  [85] "2015-01-21" "2015-01-20" "2015-01-16" "2015-01-15" "2015-01-14" "2015-01-13"
  [91] "2015-01-12" "2015-01-09" "2015-01-08" "2015-01-07" "2015-01-06" "2015-01-05"
  [97] "2015-01-02" "2014-12-31" "2014-12-30" "2014-12-29" "2014-12-26" "2014-12-24"
 [103] "2014-12-23" "2014-12-22" "2014-12-19" "2014-12-18" "2014-12-17" "2014-12-16"
 [109] "2014-12-15" "2014-12-12" "2014-12-11" "2014-12-10" "2014-12-09" "2014-12-08"
 [115] "2014-12-05" "2014-12-04" "2014-12-03" "2014-12-02" "2014-12-01" "2014-11-28"
 [121] "2014-11-26" "2014-11-25" "2014-11-24" "2014-11-21" "2014-11-20" "2014-11-19"
 [127] "2014-11-18" "2014-11-17" "2014-11-14" "2014-11-13" "2014-11-12" "2014-11-11"
 [133] "2014-11-10" "2014-11-07" "2014-11-06" "2014-11-05" "2014-11-04" "2014-11-03"
 [139] "2014-10-31" "2014-10-30" "2014-10-29" "2014-10-28" "2014-10-27" "2014-10-24"
 [145] "2014-10-23" "2014-10-22" "2014-10-21" "2014-10-20" "2014-10-17" "2014-10-16"
 [151] "2014-10-15" "2014-10-14" "2014-10-13" "2014-10-10" "2014-10-09" "2014-10-08"
 [157] "2014-10-07" "2014-10-06" "2014-10-03" "2014-10-02" "2014-10-01" "2014-09-30"
 [163] "2014-09-29" "2014-09-26" "2014-09-25" "2014-09-24" "2014-09-23" "2014-09-22"
 [169] "2014-09-19" "2014-09-18" "2014-09-17" "2014-09-16" "2014-09-15" "2014-09-12"

这是一小部分。有5700行...

Answer 1

1）请尝试@Override public boolean onTouchEvent(MotionEvent event) { if(event.getAction() == MotionEvent.ACTION_UP) { ImageVIew view ...; Drawable drawable = view.getBackground(); Rect myRect = drawable.getBounds(); if (myRect.contains((int) event.getX(), (int) event.getY())) { //you can compare the distance and choose what to do ! //means pressed on your imageView } return true; } else { return false; } }，如下所示：

tapply

或者这个：

dates <- c("2015-05-13", "2015-05-12", "2015-05-11", "2015-04-27", 
      "2015-04-24", "2015-04-23")

tapply(dates, substr(dates, 1, 7), max)

2）如果日期在数据框中：

library(zoo)
tapply(dates, as.yearmon(dates), max)

或将DF <- data.frame(dates, stringsAsFactors = FALSE) aggregate(DF["dates"], list(month = substr(DF$dates, 1, 7)), max)替换为substr(...)。

3）这会挑出每个月的最后一行。在这种情况下，as.yearmon(DF$dates)返回一个字符变量，因此需要使用ave将其转换为逻辑：

as.logical

或使用isMax <- function(x) seq_along(x) == which.max(as.Date(x)) subset(DF, as.logical(ave(dates, substr(dates, 1, 7), FUN = isMax)))代替as.yearmon(dates)。 substr(...)的以下定义可以替换

isMax

并给出相同的结果，除非有多个最大值。在这种情况下，它只给出第一个，而早期的定义给出了所有。由于isMax <- function(x) seq_along(x) == which.max(as.Date(x))不适用于which.max类，因此我们将日期转换为"character"类。

下次请使用"Date"显示您的数据或以其他方式提供可重复的格式，如上所述。同时将其降低到说明问题所需的最小量。

Answer 2

以下是一种替代解决方案，使用dplyr按月和年分组，然后过滤max，即每年的最后日期：

df <- data.frame(dates=as.Date(c("2015-05-21", "2015-05-20", "2015-05-19", "2015-05-18",
                 "2015-05-15", "2015-05-14","2014-12-05", "2014-12-04", "2014-12-03",
                 "2014-12-02", "2014-12-01", "2014-11-28")))

library(dplyr)

df %>% 
  group_by(strftime(dates, "%Y-%m")) %>% #Groups by the yearmonths
  filter(dates == max(dates)) %>%        #Take the last date of each group
  .$dates                                #Returns the filtered dates as a vector

导致：

[1] "2015-05-21" "2014-12-05" "2014-11-28"

感谢@akrun提供有关修复和改进代码的提示。

Answer 3

如果你有一个数据框，＆＃39; a＆＃39;包括日期变量，＆＃39; date＆＃39;，

ClassNotFoundExeption

例如：

library(dplyr)
a<-mutate(a,endmonth=as.Date(paste0(as.numeric(format(date,"%Y%m"))+1,"01"),"%Y%m%d")-1)

在数据框中查找每个月的最后日期

3 个答案: