ggpmisc消除了对汇总数据长度的困惑

Question

我收到了这个错误消息"Error in data.frame(mean_Flow，dates)：arguments differing number of rows: 84,30274“，我知道它对我想要拉取哪个日期函数感到困惑，但我不确定如何清除它。我想要将数据汇总为年度平均值。它正确地绘制了这段代码，但没有生成正确的stat_poly_eq。如果有任何帮助，我将不胜感激！

library(dataRetrieval)
library("plyr")
siteNo = "02202500"
pCode = "00060"

daily = readNWISdv(siteNo, pCode, "1800-10-01","2020-09-30", statCd="00003")
daily = renameNWISColumns(daily)
dates= format(as.Date(daily$Date), format = "%Y")
ddply(daily, .(site_no, dates), summarise,
      mean_Flow = mean(Flow)*(0.0283168))

library(dplyr)
library(ggpmisc) # for dealing with stat equations
library(ggplot2) # for making plots 
library(lubridate) # for working with dates
library(scales) #for working with date_format

df=data.frame(mean_Flow, dates)
head(df)
df$dates = as.Date(df$dates, format = "%Y")
my.formula = df$mean_Flow ~ df$dates

p1=ggplot(data = df,aes(dates, mean_Flow)) +
  geom_line(group = 1) +
  geom_smooth(method = "lm", se=FALSE) +
  stat_poly_eq(formula = my.formula,
               eq.with.lhs = "italic(hat(y))~`=`~",
               aes(label = paste(..eq.label.., ..rr.label.., sep = "~~~")))+
  theme_classic()+
  labs(x="", y=(expression(Discharge~(m^{3}~s^{-1}))))+
  scale_x_date(breaks = "5 year", labels = date_format("%Y"))+
  theme(axis.text.x = element_text(angle = 45, hjust = 1))
p1

Answer 1

传递给stat_poly_eq()的公式在"data“中求值，就像在ggplot层中看到的那样:即，必须使用变量映射到的美学的名称，而不是使用df中的变量名称。换句话说，@Richard Telford正确地猜到了问题所在。此行为与stat_smooth()的行为相同，对于该行为，上面的代码使用formula的默认值y ~ x。