# Week 2

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## 2. Basic ideas

### 2.2. aesthetic mapping

2.2.1. how data are mapped to color, size

2.2.2. aes parameter

### 2.3. geoms

2.3.1. geometric objects

### 2.4. facets

2.4.1. for conditional plots

### 2.5. stats

2.5.1. Statistical transformations

### 2.6. scales

2.6.1. mappings like: males - blue, female - red

### 2.8. Plots build in layers

2.8.1. PLot data

2.8.2. Overlay a summary

### 2.9. ggplot() returns an object - can assign it to object

2.9.1. g <- ggplot(...)

2.9.2. p <- g + geom_point()

2.9.2.1. geom_line()

2.9.3. print(p)

2.9.4. p + geom_smooth(method = "lm")

2.9.5. p + facet_grid(. ~ bmicat)

### 2.11. theme() for global options

2.11.1. theme(legend.position = "none")

2.11.2. prebuilt theme

2.11.2.1. theme_gray() = default

2.11.2.2. theme_bw()

### 2.12. Как можно убрать outlier из графика

2.12.1. g + geom_line() + coord_cartesian(ylim = c(-3, 3))

2.12.2. график будет ограничен между -3 и 3

### 2.13. Если надо построить график зависимости от непрерывной переменной, то надо разрезать её на factor'ы

2.13.1. cutpoints <- quantile(data, seq(0, 1, length = 4), na.rm = T)

2.13.2. fac <- cut(data, cutpoints)

2.13.3. use fac to build the chart

## 3. Lattice

### 3.2. lattice package

3.2.1. depends on grid package

3.2.1.1. rarely used by user

### 3.4. Functions

3.4.1. xyplot

3.4.1.1. xyplot(y ~ x | f * g, data)

3.4.1.1.1. f * g - conditional variables, по ним идет фильтрация

3.4.1.1.2. xyplot(Ozone ~ Wind | Month, data =airquality, layout = c(5,1))

3.4.2. bwplot

3.4.3. histogram

3.4.4. stripplot

3.4.5. dotplot

3.4.6. splom

3.4.7. levelplot

3.4.8. contourplot

### 3.5. Returns object of type trellis

3.5.1. trellis plot object is plotted due to auto-print of R

3.5.2. Can write: p <- xyplot(...) print(p) # here graph will appear

### 3.6. Panel functions

3.6.1. Controls what happens in panels

3.6.3. Argument in xyplot function

3.6.4. Every function should be from lattice package or your own, not from base package

## 4. ggplot2

### 4.3. qplot()

4.3.1. Looks for data

4.3.2. plots are made up of aesthetics and geoms

4.3.3. Uses factors heavilty to subset data

4.3.3.1. They should be labeled

4.3.3.2. qplot(displ, hwy, data = mpg, color = drv)

4.3.3.3. Legend is created automatically

4.3.3.4. qplot(displ, hwy, mpg, geom = ("point", "smooth")

4.3.3.4.2. Can specify model by parameter method = "lm"

4.3.3.5. Histogram: qplot(hwy, data = mpg, fill = drv)

4.3.3.6. geom = "density" draws density smooth

4.3.4. facets - panels in Lattice

4.3.4.1. qplot(displ, hwy, data = mpg, facets = . ~ drv)

4.3.4.1.1. . ~ drv говорит, что должно быть по колонке на каждое значение drv

4.3.4.2. qplot(displ, hwy, data = mpg, facets = drv ~ ., bandwidth = 2)

4.3.4.2.1. drv ~ . говорит, что по строчке, на каждое значение drv