R:在绘制日期时找到刻度线的位置

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我正在运行一个R脚本，该脚本使用 plot 随时间绘制数据并以 as.Date 提取一些数据.然后，我使用 grid 添加以添加如下准则:

I'm running an R script which plots data over time using plot and some data taken as.Date. I am then adding using grid to add guidelines like so:

plot(as.Date(data[["Date"]]), -data[["dbns"]], lwd=1, col = colours[i], type="l",ylim=ylimit, xlim=xlimit, xlab="", ylab =ylabel) grid(NULL,NULL,lwd=1)

下面是一个如何显示结果的示例(实际上是在将此图循环3次以添加每行之后的示例)

Below is an example of how this comes out (actually example is after this plot is looped over 3 times to add each line)

我遇到的问题是，在 grid 中添加的指南与 plot 中添加的默认刻度线不一致.默认情况下，plot函数每10年添加一次滴答，这就是我想要的.查看 axTicks(1)给我 0 5000 10000 15000 ，它是准则的位置，以1970年1月1日之后的天数为单位.

The problem I am having is that the guidelines added with grid do not line up with the default tick marks added by plot. The plot function by default adds tick every 10 years, which is what I want. Looking at axTicks(1) gives me 0 5000 10000 15000 which is the locations of guidelines in units of days after 1/1/1970.

是否有办法找出已添加的刻度线的位置?而且更重要的是，然后有一种方法可以设置准则以匹配这些位置吗?

Is there a way to find out the location of the tickmarks that have been added? And more importantly, is there then a way to set the guidelines to match these locations?

我意识到，在这个示例中，刻度是 [0，365.25 * 10，365.25 * 20等] ，但是解决一般情况的答案会很好.

I realise that for this example the ticks are [0, 365.25*10, 365.25*20 etc.] but an answer which solves a general case would be nice.

谢谢

JP

这是一个可复制的示例，用于确切说明我的意思.

Here is a reproducible example to show exactly what I mean.

data <- read.csv("test.csv"), header =TRUE) data[["Date"]] <- as.Date(data[["Date"]], format = "%d/%m/%Y") data<-data[order(as.Date(data$Date)),] plot(as.Date(data[["Date"]]), -data[["dbns"]], type="l", xlim=xlimit) grid(NULL,NULL,lwd=3)

文件test.csv如下所示(实际数据的提取)

Where the file test.csv looks like this (extract of actual data)

bore Date dbns 42230210A 20/01/2009 13.13 42230210A 8/05/2009 13.21 42230210A 18/06/2009 13.19 42230210A 3/08/2009 13.2 42230210A 2/09/2009 13.25 42230210A 1/10/2009 13.3 42230210A 3/12/2009 13.32 42230210A 24/02/2010 13.3 42230210A 18/05/2010 13.3 42230210A 25/04/2012 11.45 42230210A 27/09/1966 11.18 42230210A 28/10/1969 11.14 42230210A 6/01/1970 11.03 42230210A 5/06/1973 10.68 42230210A 28/08/1973 10.63 42230210A 2/10/1973 10.73 42230210A 4/12/1973 10.7 42230210A 20/02/1980 11.39 42230210A 29/04/1980 11.45 42230210A 27/08/1980 11.45 42230210A 22/06/1988 11.14 42230210A 27/02/1996 11.78 42230210A 6/08/1996 11.68 42230210A 8/02/2000 11.64 42230210A 8/06/2000 11.71 42230210A 7/09/2000 11.75 42230210A 15/07/2008 13.01

其输出如下.准则偏离了刻度线?

The output of which is below. The guidelines are offset from the tick marks?

推荐答案

所以检查?grid 表明发生了什么事，它是根据默认"刻度线位置放置网格线，但由于您已绘制日期对象，因此R并未使用默认值"(在将日期视为数字变量的意义上)来放置刻度线.

So checking ?grid suggests that what's going on is that it is placing the grid lines based on the "default" tick mark locations, but since you plotted a date object, R didn't use the "default" (in the sense of treating the date as a numeric variable) to place the tick marks.

文档进一步指出，如果需要更好的控制，则应使用 abline 直接放置它们.

The documentation further notes that if you need finer control, you should use abline to place them directly.

所以您可能想这样做:

plot(as.Date(data[["Date"]]), -data[["dbns"]], type="l") grid(NA,NULL,lwd=3) v <- as.numeric(as.Date(paste0(c(1970,1980,1990,2000,2010),'-01-01'))) abline(v = v,lty = "dotted",col = "lightgray",lwd = 3)