qplot

Why qplot???

qplot makes it easy to

produce complex plots, often requiring several lines of code using other plotting

systems, in one line. qplot() can do this because it's based on the grammar

of graphics, which allows you to create a simple, yet expressive, description

of the plot.

"ggplot2, Hadely wickham"

1. qplot

qplot( x, y, data, geom, facets, colour.fill)

1.1) Colour, Shape

qplot(carat, price, data = diamonds, colour = color )

qplot(carat, price, data = diamonds, shpae= color )

1.2) Transparency

qplot(carat, price, data =diamonds, alpha = I(1/20))

alpha : 투명도

data가 많을 때, 그냥 plot으로 그릴 경우 한눈에 들어오지 않음

1.3) Add Smooth line to chart

qplot(carat, price, data = sample_n(diamonds,1000) , geom = c("point", "smooth"),

      span = 0.2)

span : wiggly (구불거림의 정도 설정)

sample_n : dplyr package

sample size가 클경우 아래 방식을 사용 ( n > 1000)

library(mgcv)

qplot(carat, price, data = dsmall, geom = c("point", "smooth"),

method = "gam", formula = y ~ s(x))

qplot(carat, price, data = dsmall, geom = c("point", "smooth"),

method = "gam", formula = y ~ s(x, bs = "cs"))

library(splines)

qplot(carat, price, data = dsmall, geom = c("point", "smooth"),

method = "lm")

fits linear model

qplot(carat, price, data = dsmall, geom = c("point", "smooth"),

method = "lm", formula = y ~ ns(x,5))

fits natural spline line