Plotting

Question 1

generate random normal variates, with a given mean and std dev

Answer 1

rnorm()

Question 2

evaluate the normal probability density, for a given mean and standard deviation

Answer 2

dnorm() - evaluates the lower tail by default

Question 3

generate random binary random variable

Answer 3

rbinom() - binomial distribution

Question 4

Take a sample from a range of numbers without replacement or with replacement

Answer 4

sample(1:10, 4) will get 5 2 1 9

sample(1:10, 4, replacement = T) will get 5 2 1 5

Question 5

How to see the parameters of the base graphics system

Answer 5

type in :

?par - “coursera - memorize this page”

Question 6

The main two functions of the base plotting system

Answer 6

hist()

plot(x,y)

Question 7

set margins in base plotting

Answer 7

par(mar = c(2,2,2,2)) # this bottom, left, top, right

Question 8

plot line on scatterplot

Answer 8

use abline()
abline(vector, lwd = 3, col = 'blue')

Question 9

Label x and y axis

Answer 9

plot(x,y, xlab = ‘label’, ylab ‘label’, main = ‘scatterplot’)

Question 10

put multiple plots on the page

Answer 10

1. setup par(mfrow=c(2,1)) creates a pane of 2 rows one column
2. plot(x,y) #first plot
3. plot(x,y) #second plot
   you set things up by using par(mfrow =

Question 11

alternate way to setup canvas than mfrow

Answer 11

mfcol() does column, rows

Question 12

add data to existing plots

Answer 12

points()

points(x[g==’Male’], y[g==’Male’], col = ‘Blue’)

Question 13

par variable that controls the type of shape (open circle, filled circle, etc_)

Answer 13

pch

Question 14

see examples of different values for plotting symbols (circle, filled circle, etc)

Answer 14

example(pch)

Question 15

add label to coordinate in scatterplot

Answer 15

text(x,y, ‘label’)

Question 16

add legend to plot

Answer 16

legend(‘topleft’, legend = ‘data’, pch = 20)

Question 17

make a scatterplot in lattice

Answer 17

xyplot(y~x | f) # shows the relationship b/w x and y before men and women separately, whatever after pipe is the condition you want to group by. A separate panel will be created for each categorization.

Question 18

Using functions in the base plotting system in lattice

Answer 18

YOU CANT DO THIS, once you are in the “lattice” world, you can only use lattice functions. There are generally analgous functions to the baseplot in lattice.

Question 19

How do you use the lattice package

Answer 19

library(lattice)

Question 20

View help page on package

Answer 20

package ? lattice

library(help = lattice)

Question 21

scatterplot matrix in lattice package

Answer 21

splom(~dataframe)

Question 22

main function in ggplot

Answer 22

qplot()

Question 23

data type needed for ggplot

Answer 23

data.frame

Question 24

talk about facets parameter of qplot function

Answer 24

the paremeter is defined by rows~columns
facets = .~var then you will have three tables side by side in one row separated by 3 columns
facets = var~. then you will have three tables stack on top of eachother in one column but three rows