在时间序列的stat\u bin中使用seq.Date作为中断

我可以把你的错误重现如下:

> break.dates <- seq.Date(from=as.Date('2001-01-01'),
                          to=as.Date('2001-04-01'),
                          by="month") 
> break.dates
[1] "2001-01-01" "2001-02-01" "2001-03-01" "2001-04-01"
## add an offset, which increases the dates by a day
> break.dates + 1
[1] "2001-01-02" "2001-02-02" "2001-03-02" "2001-04-02"
## try to add two date objects together - this does not make sense!
> break.dates + break.dates
Error in `+.Date`(break.dates, break.dates) :
  binary + is not defined for Date objects

把两个日期加在一起是没有意义的,因为日期表上没有自然的“零”。然而 + Date

在其他情况下,当我从ggplot2中得到这个错误时,我就可以在用于中断的序列周围使用as.numeric()了。例如,

library(lubridate)
library(ggplot2)
library(scales)

somedates <- ymd(20130101) + ddays(runif(100, 0, 364)) #generate some fake event dates
somedatesformatted <- data.frame(Dates=as.Date(somedates)) #format them as data ggplot likes
monthbins <- as.numeric(seq(as.Date('2013-01-01'), as.Date('2014-01-01'), '1 month')) # generate breaks for binning event dates and wrap in as.numeric()

ggplot(somedatesformatted, aes(x=Dates)) + 
    stat_bin(breaks=monthbins) +
    ylab("Events per Month") +
    ylim(c(0,30)) +
    scale_x_date(breaks = '1 month',
             labels = date_format("%b"),
             limits = c(as.Date('2013-01-01'), as.Date('2013-12-31')))

在我看来,如果你先变换数据,你也能得到同样的结果, 将其传递给plot方法。

例如(以月份为单位的时间序列数据按年份分类):

data(AirPassengers)   # time series in months (supplied w/ default R install)
AP = AirPassengers
library(xts)
X = as.xts(AP)      # need xts object to pass to xts binning method
ndx = endpoints(X, on="years")    # binning method requires indices for desired bin freq
X_yr = period.apply(x=X, INDEX=ndx, FUN=sum)   # X_yr is the binned data