R作图系列-----ggplot2-qplot
diamonds数据结构
| carat | cut | color | clarity | depth | table | price | x | y | z | |
|---|---|---|---|---|---|---|---|---|---|---|
|
1
|
0.38
|
Ideal
|
E
|
VS1
|
60.8
|
56.0
|
940
|
4.70
|
4.75
|
2.86
|
|
2
|
0.30
|
Ideal
|
E
|
VS2
|
61.7
|
55.0
|
658
|
4.30
|
4.32
|
2.66
|
|
3
|
0.76
|
Very Good
|
G
|
VS2
|
62.1
|
54.0
|
2990
|
5.88
|
5.94
|
3.67
|
|
4
|
2.02
|
Premium
|
G
|
SI2
|
60.1
|
59.0
|
17099
|
8.29
|
8.21
|
4.96
|
|
5
|
0.70
|
Premium
|
F
|
SI2
|
58.4
|
61.0
|
1966
|
5.86
|
5.79
|
3.40
|
|
6
|
1.05
|
Ideal
|
H
|
SI2
|
60.6
|
57.0
|
3234
|
6.59
|
6.55
|
3.98
|
- ggplot2对数据框类型数据十分友好，colour\shape\size必须赋值等于常数或数据框中的分类变量（因子类型数据）
- geom=point/smooth
dsmall <- diamonds[sample(nrow(diamonds), 100), ] qplot(carat, price, data = diamonds) ##1.基本aesthetic attributes :colour\shape\size\alpha qplot(carat, price, data = dsmall, colour = color) qplot(carat, price, data = dsmall, shape = cut) qplot(carat, price, data = diamonds, alpha = I(1/10)) ###You can also manually set the aesthetics using I() #####2.geometric object ###2.1 smooth method到底用什么方法 可以加载不同的包 如MASS 按相应的回归formula输入即可 qplot(carat, price, data = dsmall, geom = c("point", "smooth")) #####默认小样本（小于1000）使用局部回归 qplot(carat, price, data = dsmall, geom = c("point", "smooth"),span = 0.2) #span调整平滑程度 library(mgcv) qplot(carat, price, data = dsmall, geom = c("point", "smooth"),method = "gam", formula = y ~ s(x, bs = "cs")) #####默认大样本（大于1000）的回归算法 qplot(carat, price, data = dsmall, geom = c("point", "smooth"),method = "lm") #最小二乘
- Boxplots and jittered points（扰动点图）
- geom=jitter/boxplot
- how the values of the continuous variables vary with the levels of the categorical variable(一个连续变量、一个分类变量）
qplot(color, price / carat, data = diamonds, geom = "jitter",alpha = I(1 / 5)) #第一个参数是分类变量，第二个是连续变量 qplot(cut,price/carat,data=dsmall,geom=c('jitter','boxplot'),alpha=I(0.5),colour=cut)##jitter boxplot 可以一起用 ##boxplot中colour是外框线颜色，fill是填充颜色,size是线的粗细
- geom=histogram\density\bar
- histogram：binwidth(组距）、xlim=c(...,...)
- density,adjust(取值0到1，平滑程度)
qplot(carat, data = diamonds, geom = "histogram", binwidth = 0.01,xlim = c(0,3)) ##histogram默认Y轴为频数 qplot(carat, data = diamonds, geom = "histogram", fill = color) #使用fill参数可以很快得到堆积柱形图 qplot(color, data = diamonds, geom = "bar", weight = carat) +scale_y_continuous("carat") #y轴不再是频数，而是对给定的weight求和，+号后面的代码是变坐标轴名称count为carat
- geom=line/path
year <- function(x) as.POSIXlt(x)$year + 1900 #as.POSIXlt(x)读取的日期（字符串） 转化为 “Date” 类型数据 qplot(unemploy / pop, uempmed, data = economics,geom = c("point", "path")) qplot(unemploy / pop, uempmed, data = economics,geom = "path", colour =year(date)) + scale_size_area() #按年份更换颜色
- 分组画图 facets
qplot(carat, price, data = dsmall, facets = color ~ .,geom = "point",xlim = c(0, 3)) #facets = row var ∼ col var #指定行变量和列变量拆分绘图窗格
fill = I("blue")显示蓝色 ##用I()告诉R，blue是参数不是变量
xlim, ylim x轴y轴的范围 xlim = c(0, 3)
log 对数变换 log="xy" x轴和y轴都进行对数变换
qplot(carat, price, data = dsmall, log = "xy")
main 图的标题
xlab, ylab x轴y轴的标题 ylab = expression(frac(price,carat)) ##显示为price/carat表达式 更多表达式?plotmath获得
将变量传递给指定的图形属性，如钻石颜色（分类变量）到颜色，这是一个映射过程，官方称作scale，画布上会显示图例。
