気温の近似曲線を描く

kion_kinji.r

library(ggplot2)

kion = read.csv("kion_20160501.csv", header = T, colClasses = c("POSIXct", "numeric"))
head(kion)
summary(kion)

g = ggplot(kion, aes(1:nrow(kion), temp)) + geom_line(colour="blue") + labs(title="2016/05/01")
plot(g)

x = 1:nrow(kion)
y = kion[,2]

kinji = nls(y ~ a * x^3 + b * x^2 + c * x + d, start=c(a=0, b=0, c=0, d=0))
summary(kinji)

predict.c = predict(kinji)
kd = data.frame(predict.c)
kd$num = 1:nrow(kion)

coef = coefficients(kinji)
coef[1]
coef[2]
coef[3]
coef[4]

k = geom_line(aes(kd$num, kd$predict.c), colour="red")
a = annotate("text", label= "y = -0.009 * x^3 + 0.285 * x^2 -1.64 * x + 14.62", x=7, y=25, col="red")
plot(g + k + a)