Plotting

Question 1

plot(x)

Answer 1

plot of the values of x (on the y-axis) ordered on the x-axis

Question 2

plot(x, y)

Answer 2

bivariate plot of x (on the x-axis) and y (on the y-axis)

Question 3

hist(x)

Answer 3

histogram of the frequencies of x

Question 4

barplot(x)

Answer 4

histogram of the values of x; use horiz=FALSE for horizontal

bars

Question 5

dotchart(x)

Answer 5

if x is a data frame, plots a Cleveland dot plot (stacked plots
line-by-line and column-by-column)

Question 6

pie(x)

Answer 6

circular pie-chart

Question 7

boxplot(x)

Answer 7

“box-and-whiskers” plot

Question 8

sunflowerplot(x, y)

Answer 8

id. than plot() but the points with similar coor-
dinates are drawn as flowers which petal number represents the num-
ber of points

Question 9

stripplot(x)

Answer 9

plot of the values of x on a line (an alternative to

boxplot() for small sample sizes)

Question 10

coplot(x ̃y | z)

Answer 10

bivariate plot of x and y for each value or interval of

values of z

Question 11

interaction.plot (f1, f2, y)

Answer 11

if f1 and f2 are factors, plots the
means of y (on the y-axis) with respect to the values of f1 (on the x-axis) and of f2 (different curves); the option fun allows to choose the summary statistic of y (by default fun=mean)

Question 12

matplot(x,y)

Answer 12

bivariate plot of the first column of x vs. the first one of y, the second one of x vs. the second one of y, etc.

Question 13

fourfoldplot(x)

Answer 13

visualizes, with quarters of circles, the association be- tween two dichotomous variables for different populations (x must be an array with dim=c(2, 2, k), or a matrix with dim=c(2, 2) if k = 1)

Question 14

assocplot(x)

Answer 14

Cohen–Friendly graph showing the deviations from inde- pendence of rows and columns in a two dimensional contingency ta- ble

Question 15

mosaicplot(x)

Answer 15

‘mosaic’ graph of the residuals from a log-linear regres- sion of a contingency table

Question 16

pairs(x)

Answer 16

if x is a matrix or a data frame, draws all possible bivariate plots between the columns of x

Question 17

plot.ts(x)

Answer 17

if x is an object of class “ts”, plot of x with respect to time, x may be multivariate but the series must have the same frequency and dates

Question 18

ts.plot(x)

Answer 18

id. but if x is multivariate the series may have different dates and must have the same frequency

Question 19

qqnorm(x)

Answer 19

quantiles of x with respect to the values expected under a nor- mal law

Question 20

qqplot(x, y)

Answer 20

quantiles of y with respect to the quantiles of x

Question 21

contour(x, y, z)

Answer 21

contour plot (data are interpolated to draw the curves), x and y must be vectors and z must be a matrix so that
dim(z)=c(length(x), length(y)) (x and y may be omitted)

Question 22

filled.contour(x, y, z)

Answer 22

id. but the areas between the contours are

coloured, and a legend of the colours is drawn as well

Question 23

image(x, y, z)

Answer 23

id. but with colours (actual data are plotted)

Question 24

persp(x, y, z)

Answer 24

id. but in perspective (actual data are plotted)

Question 25

stars(x)

Answer 25

if x is a matrix or a data frame, draws a graph with segments or a
star where each row of x is represented by a star and the columns are
the lengths of the segments

Question 26

symbols(x, y, …)

Answer 26

draws, at the coordinates given by x and y, sym-
bols (circles, squares, rectangles, stars, thermometres or “boxplots”)
which sizes, colours . . . are specified by supplementary arguments

Question 27

termplot(mod.obj)

Answer 27

plot of the (partial) effects of a regression model

mod.obj

Question 28

add=FALSE

Answer 28

if TRUE superposes the plot on the previous one (if it exists)

Question 29

axes=TRUE

Answer 29

if FALSE does not draw the axes and the box

Question 30

type=”p”

Answer 30

specifies the type of plot, “p”: points, “l”: lines, “b”: points
connected by lines, “o”: id. but the lines are over the points, “h”: vertical lines, “s”: steps, the data are represented by the top of the vertical lines, “S”: id. but the data are represented by the bottom of the vertical lines

Question 31

xlim=, ylim=

Answer 31

specifies the lower and upper limits of the axes, for exam- ple with xlim=c(1, 10) or xlim=range(x)

Question 32

xlab=, ylab=

Answer 32

annotates the axes, must be variables of mode character

Question 33

main=

Answer 33

main title, must be a variable of mode character

Question 34

sub=

Answer 34

sub-title (written in a smaller font)