当范围每天都在变化时，如何使用 plot() 调整 x 轴？答案

【问题标题】：How to adjust x-axis using plot() when range is changing daily?当范围每天都在变化时，如何使用 plot() 调整 x 轴？
【发布时间】：2016-03-29 12:35:20
【问题描述】：

我想在绘制一些预测时更改 x 轴。该模型每天通过 crontab 更新。 x 比例必须包括日期的每日增加量：

示例数据：

# where dates changes according to Sys.Date-1
dates <- seq(as.Date("2015-01-01"), Sys.Date()-1, by = "days")
# where x is updated daily
x <- diffinv(rnorm(length(dates)-1))
df<-data.frame(dates,x)

# split data and train model
 df$x<-as.ts(df$x)

# required libraries
library(caret)
library(forecast)
library(plyr) 

# the time series is updated on daily basis
date1 <- strptime("2016-02-04", format="%Y-%m-%d")
date2 <- strptime(Sys.time()-1, format="%Y-%m-%d")
date3<-difftime(date2,date1,units="days")

 # here I split data into time and test data according to initialWindow "2016-02-04"
 timeSlices <- createTimeSlices(1:nrow(df), 
                           initialWindow = 400, horizon = date3, fixedWindow = TRUE)

#extract data for fitting the model
trainSlices <- timeSlices[[1]]
testSlices <- timeSlices[[2]]

# here I calculate the fit and forecast
fit <- tbats(df[trainSlices[[1]],]$x, seasonal.periods=c(7,365), use.trend=TRUE, use.parallel=TRUE)
 pred <- forecast(fit,h=length(df[testSlices[[1]],]$x))

# here I plot actual vs. predicted values
 plot(forecast(fit,h=length(df[testSlices[[1]],]$x)),ylab = "x ",xlab="Daily units from 2015-01-01 to CurrentDate", main="Forecast", include=30)
 lines(x = as.numeric(rownames(df[testSlices[[1]],])), df[testSlices[[1]],]$x, col = "red")
 legend(x = "topleft", legend = c("Prediction", "Actual Data"), col = c("blue", "red"), lty = c(1, 1))

我想把每日单位改成dates scale又名2015-07-01等等，这也在每日更新中有所体现。我尝试使用xaxt="n" 并添加dates scale 和Sys.Date()-1：

dates <- seq(Sys.Date()-30, Sys.Date()-1, by = "days")
plot(xaxt="n",forecast(fit,h=length(df[testSlices[[1]],]$x)),ylab = "x ",xlab="Daily units from 2015-01-01 to CurrentDate", main="Forecast", include=30)
 lines(x = as.numeric(rownames(df[testSlices[[1]],])), df[testSlices[[1]],]$x, col = "red")
 legend(x = "topleft", legend = c("Prediction", "Actual Data"), col = c("blue", "red"), lty = c(1, 1))
   # here I wanted to add the new scale
axis(1, at = dates,labels = TRUE)

但这并没有绘制 x 比例。

【问题讨论】：

您是否仅限于基础地块或也可以使用ggplot 解决方案？
我不受限制。我只使用base，因为library(forecast)不支持ggplot，至少我不能使用它。
另见here和here。

标签： r plot

【解决方案1】：

axis() 不显示的原因是include =30 只显示窗口中的最后 30 个元素，但实际上轴从 1 开始。

如果您将轴滑动到当前窗口，则会显示：

plot(xaxt="n",forecast(fit,h=length(df[testSlices[[1]],]$x-1)),ylab = "x ",xlab="Daily units from 2015-01-01 to CurrentDate", main="Forecast", include=30)
lines(x = as.numeric(rownames(df[testSlices[[1]],])), df[testSlices[[1]],]$x, col = "red")
legend(x = "topleft", legend = c("Prediction", "Actual Data"), col = c("blue", "red"), lty = c(1, 1))
at  <-  seq(1,as.integer(date3),length.out=4)
dates <- seq(date1, date2, by="days")[at]
axis(1, at = at+400, labels = dates)

【讨论】：