ggplot2段 - 当x轴是时间时的方向 [英] ggplot2 segment -- direction when x-axis is time
问题描述
我有一个风速和风向时间序列，我正在试图用线段来描绘风速和方向。我需要从每个点（这是我挂起的位置）的线段得到风速对时间（我可以创建）的基点散点图。线的长度必须与风速成比例，该角度需要风向。我正在使用ggplot2和geom_segment，但是因为x是时间，我无法找到正确的公式来用于xend。
下面是一个数据框的例子：
以下是我的代码：
<$ p code $ library $ g $ b $ library $ lub
$ b $ gustav< - read.csv（C：/ Users / ezco3 / My Research / LPBF / Pontchartrain-Maurepas Surge Consortium / Projects / Lake Tilting Effect Graphic / Datasets / Gustav_NewCanal_Hydro& Metero.csv）
Gustav $ TS < - as.POSixct（Gustav $ DateTime，％m /％d /％Y％H：％M，tz =America / Chicago）
Gustav $ DelY < - Gustav $ WINDSPEED_MPH * sin（Gustav $ DIR）/ max（Gustav $ WINDSPEED_MP H，na.rm = TRUE）
Gustav $ DelX< - Gustav $ WINDSPEED_MPH * cos（Gustav $ DIR）/ max（Gustav $ WINDSPEED_MPH，na.rm = TRUE）
plt1 < - ggplot（data = Gustav，aes（x = TS，y = WINDSPEED_MPH））
plt1 + geom_point（color =blue）+
geom_segment（data = Gustav，mapping = aes（x = TS，y = WINDSPEED_MPH，xend = TS + 18000 * DelX，
yend = WINDSPEED_MPH + 5 * DelY），size = .1，color =red）
然后，创建这个：
DelX前面的18000和DelY前面的5个都是通过跟踪和错误找到的任意数字。基本上，最初只使用DelX和DelY（没有乘法器）线是短而垂直的，所以我通过不同的选择，直到我发现这对显示一些方向的线。
然而，角度不正确。在这个阶段，我不明白单元如何与lubridate中的时间序列对象一起工作，所以我迷失于如何计算xend的正确公式。
任何建议都将非常感谢。
谢谢！
使用@ eipi10的建议计算合适的比率并乘以x中的更改，但不明确设置坐标限制，这里有一个正确显示45度风向的解决方案，并且该段的长度对应于风速。
date< - seq（ymd（'2012-04-07'），ymd（'2013-03-22'），by ='day'）
windspeed < - rnorm（n =长度（日期），平均值= 5（sd = 1）
dir < - rep（（c（0,30,45,60,90）*（pi / 180）），times = length（date）/ 5）
data < - data.frame（date，windspeed，dir）
rat <-as.numeric（interval（min（date），max（date）））/（max （风速） - min（风速））
data < - data％>>％
mutate（DelY = windspeed * sin（dir）/（2 * max（windspeed）），
DelX = rat * windspeed * cos（dir）/（2 * max（windspeed））
$ b plt1< - ggplot（data = data， aes（x =日期，y =风速））
plt1 + geom_po int（color =blue）+
geom_segment（aes（x = date，y = windspeed，xend = date + DelX，
yend = windspeed + DelY），size = .1，color =红色）+
coord_fixed（ratio = rat）
I have a wind speed and direction times series and I am trying to make a plot that uses line segments to depict the windspeed and direction. I need to have a basic point scatter plot of windspeed vs time (which I can create) with a line segment from each point (which is where I am getting hung up.) The length of the line has to be proportional to the windspeed and the angle needs to the wind direction. I am using ggplot2 with the geom_segment, but because x is time I cannot figure the right formula to use for xend.
Here is an example of the dataframe:
Here is my code so far:
library(ggplot2)
library(lubridate)
Gustav <- read.csv("C:/Users/ezco3/My Research/LPBF/Pontchartrain-Maurepas Surge Consortium/Projects/Lake Tilting Effect Graphic/Datasets/Gustav_NewCanal_Hydro&Metero.csv")
Gustav$TS <- as.POSIXct(Gustav$DateTime, "%m/%d/%Y %H:%M", tz="America/Chicago")
Gustav$DelY <- Gustav$WINDSPEED_MPH*sin(Gustav$DIR)/max(Gustav$WINDSPEED_MPH, na.rm=TRUE)
Gustav$DelX <- Gustav$WINDSPEED_MPH*cos(Gustav$DIR)/max(Gustav$WINDSPEED_MPH, na.rm=TRUE)
plt1 <- ggplot(data = Gustav, aes(x = TS, y =WINDSPEED_MPH))
plt1 + geom_point(color="blue") +
geom_segment(data = Gustav, mapping=aes(x= TS, y = WINDSPEED_MPH, xend = TS + 18000*DelX,
yend=WINDSPEED_MPH + 5*DelY),size=.1,color="red")
And, that creates this:
The 18000 in front of DelX and the 5 in front of DelY are both arbitrary numbers that I found through trail and error. Basically, initially using just DelX and DelY (without multipliers) the lines were short and vertical, so I worked through different option until I found this pair which showed some direction to the line.
However, the angles are not correct. At this stage, I do not understand how units work with time series objects in lubridate so I am lost as to how to figure the correct formula for xend.
Any advice would be much appreciated.
Thanks!!!
Using the suggestions of @eipi10 to calculate the appropriate ratio and multiply by the change in x but not explicitly setting the coordinate limits, here's a solution that correctly displays wind directions of 45 degrees and the length of the segment corresponds to the windspeed.
date <- seq(ymd('2012-04-07'),ymd('2013-03-22'), by = 'day')
windspeed <- rnorm(n = length(date), mean = 5, sd = 1)
dir <- rep((c(0,30,45,60,90)*(pi/180)), times = length(date)/5)
data <- data.frame(date, windspeed, dir)
rat <-as.numeric(interval(min(date), max(date))) / (max(windspeed) - min(windspeed))
data <- data %>%
mutate(DelY = windspeed * sin(dir)/(2*max(windspeed)),
DelX = rat * windspeed * cos(dir)/(2*max(windspeed)))
plt1 <- ggplot(data = data, aes(x = date, y =windspeed))
plt1 + geom_point(color="blue")+
geom_segment(aes(x= date, y = windspeed, xend = date + DelX,
yend=windspeed + DelY),size=.1,color="red") +
coord_fixed(ratio = rat)
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