02b Data Structures Datasets

8/19/2019 02b Data Structures Datasets

1/96

Data Analysis & DataScience with R

Data structures in R.Build-in Datasets

By Marin Fotache

Al.I. Cuza University of Iași

Faculty of Economics and Business Administration

Department of Accounting, Information ystems andtatistics


2/96

Data structures in R


3/96

Tutorials (and code) on DataStructures

Data structures !Advanced " #y $adley %ic&'am(

'ttp)**adv+r.'ad.co.nz*Data+structures.'tml

.- aria#les !aria#les and Data tructures(

'ttps)**///.youtu#e.com*/atc'0v1D2345f6/

- + Introduction to " ) Atomic Classes

'ttps)**///.youtu#e.com*/atc'0v1-3F8A4av4E

'ttp)**repidemiology./ordpress.com*introduction+to+r+code*

.7 ectors !aria#les and Data tructures(

'ttps)**///.youtu#e.com*/atc'0v19yg:/33$s6

7+ Introduction to " ) ectors

'ttps)**///.youtu#e.com*/atc'0v1;2p'/m


4/96

Tutorials on Data Structures (cont.)

.? @ists and Data Frames !aria#les and Data tructures(

'ttps)**///.youtu#e.com*/atc'0v1Uv#">el7&9. @ogical ectors and perators !aria#les and Data

tructures(

'ttps)**///.youtu#e.com*/atc'0v129#37?-c

>+ Introduction to " ) ;atri, @ist and Data Frame'ttps)**///.youtu#e.com*/atc'0v1cEi


5/96

R script associated with thispresentation

-#KdataKstructuresKKdatasets."

'ttp)**drv.ms*s4ll@B

http://1drv.ms/1sYllLBhttp://1drv.ms/1sYllLB


6/96


7/96

Vectors o nu!"ers withse#uences

ectors can also #e created /it' a seuence> ten&integer'1 - 5*14

> ten&integer'1

[1] 5 + 7 1. 11 12 13 14

or

> ten&integer'2 - 'e/(0ro=5, to=14, y=1)> ten&integer'2

[1] 5 + 7 1. 11 12 13 14

Declare a vector of descending num#ers

> 'e/(0ro=5, to=-5, y=-1)

[1] 5 4 3 2 1 . -1 -2 -3 -4 -5

Com#ine seuences and c function> &ector - c( 2*4, *14)

> &ector

[1] 2 3 4 1. 11 12 13 14


8/96

Vectors containin$ a ran$e odates

2enerating a vector /it' dates #et/eeneptem#er -Lt' and cto#er -nd -> asMpureM dates◦ First solution:

> 'e/('te("2.146.62"), y = "y", 8engtho9t = 4)

◦ Second solution:

> 'e/('te("2.146.62"), 'te("2.1461.6.2"),

"y'")

In #ot' cases t'e result is)[1] "2.14-.-2" "2.14-.-3." "2.14-1.-.1" "2.14-1.-.2"


9/96

Vectors containin$ a ran$e oti!esta!ps

2enerating a vector /it' dates #et/eeneptem#er -Lt' and cto#er -nd -> astimestamps

◦ First solution

> 'e/(c(:%;te(2.14,,2)), y = "%Ty", 8engtho9t = 4)

◦ Second solution

> x - ' 0ort('e/(x, y="y", 8engtho9t=),

"?@-?-? ?A")

◦ Third solution

> 1-:%;te(yer=2.14,onth=,y=25,tz="BCT")

> 'e/(0ro=1,y="y",8engtho9t=)


10/96

Vectors $enerated ro! thenor!al distri"ution

ector o#ect named % contains Nve rando! values dra/n from t'e standard normaldistri#utionO values are not ordered

> x - rnor(5)

> x

[1] -.27++5++ .72+2... .55.5-.34.3+ -.5124+

5um#ers are etracted randomly, so t'at t'esame function /ill dra/ ot'er Nve num#ers)> x - rnor(5)

> x

[1] 1.3.714 -1713177 -.227+++.3+275 .42.3.14


11/96

Vectors created with unction rep (repeat)

ector %.rep contains a seuence ofnum#ers !?, 3, ( repeated t'ree times

> xreD - reD(c(5, 7, 11), 3)

> xreD[1] 5 7 11 5 7 11 5 7 11

ee t'e diPerence /it' version /'ic' useseach clause)

> xreD2 - reD(c(5, 7, 11), ech=2,tie'=3)

> xreD2

[1] 5 5 7 7 11 11 5 5 7 7 11 115 5 7 7 11 11

l " il i (


12/96

%a!ple o "uilt-in (syste!de'ned) ectors

> $etter'

[1] "" "" "c" "" "e" "0" "g" "h" "i" "E" "" "8" "" "n""o" "D" "/" "r" "'" "t" "9" "" "w" "x" "y" "z"

> $!TT!R%[1] "#" "F" "G" "" "!" "" "B" "H" ":" "I" "J" "$" "C" "K"";" " 'ttere[1] 51+. 5757 113. 531.4


13/96

Vectors o actors

Factors are nominal varia#les /'ose values 'ave a num#er oflevelsery important in data analysis and visualizationE) t/o vectors)

◦ student names

◦

student genresBot' vectors initially contain c'aracters

> ne' - c( " c8''(genre)

[1] "chrcter"


14/96

Vectors o actors (cont.)

> 9nc8''(genre)

[1] "e8e" "C8e" "e8e" "C8e" "e8e" "e8e"Genre can have only two values, so it is converted into a factor

> genre - '0ctor(genre)

> c8''(genre)

[1] "0ctor"

> 9nc8''(genre)

[1] 1 2 1 2 1 1

ttr(,"8ee8'")

[1] "e8e" "C8e"

If a non existing value is added in vector "genre", it isautomatically converted back into character> genre - c(genre, "Foy")

> c8''(genre)

[1] "chrcter"

> 9nc8''(genre)" " " " " " " " " " " " " "

F ti tti t


15/96

Functions or $ettin$ ectortype and len$th

Class returns elements data typeO unclass returns t'evalues

> c8''(ten&integer'1)[1] "integer"

> 9nc8''(ten&integer'1) [1] 5 + 7 1. 11 12 13 14

Internally, factor levels are stored as integers> c8''(genre)[1] "0ctor"

> 9nc8''(genre)[1] 1 2 1 2 1 1

ttr(,"8ee8'")[1] "e8e" "C8e"

> tyDeo0(genre)[1] "integer"

Function lengt' returns t'e num#er of elements in a vector

> 8ength(ten&integer'1)[1] 1.


16/96

Reerencin$ ector ele!entsFirst element in vector teninte$ers.*

> ten&integer'1 [1][1] 5@ast element in vector teninte$ers.*

> ten&integer'1 [8ength(ten&integer'1)]

[1] 14First t'ree elements in vector tenKintegers.

> ten&integer'1 [1*3]

[1] 5 + 7@ast t'ree elements in vector

> ten&integer'1 [(8ength(ten&integer'1)-2) *8ength(ten&integer'1)]

[1] 12 13 14First, t'ird, Nft' and sit' elements

> ten&integer'1 [c(1, 3, 5, +)]

[1] 5 7 1.


17/96


18/96


19/96

%cludin$ ele!ents ro! a ector(cont.)

Ecluding Nrst t'ree elements and t'e t'

element and t'e 6t' element

> ten&integer'1 [-(c(1*3,+,))]

[1] 11 13 14

Ecluding t'e Nrst t/o elements and

t'e last t/o elements of t'e vector)

> ten&integer'1 [-c((1*2),(8ength(ten&integer'1)-1) *8ength(ten&integer'1))]

[1] 7 1. 11 12


20/96

Vector 'lterin$

Filter vector elements + select only elements

greater t'an > ten&integer'1 [ten&integer'1 > 1.]

[1] 11 12 13 14

$o/ many elementes are greater t'an 0

> 8ength(ten&integer'1 [ten&integer'1 > 1.])[1] 4

Display I5DICE of elements greater t'an > which (ten&integer'1 > 1.)

[1] 7 1.Filter vector elements + select only elementsgreater t'an Q ver. -

> in - which (ten&integer'1 > 1.)

> ten&integer'1 [in]

[1] 11 12 13 14


21/96

Sortin$+orderin$ a ector

Initial vector

> ne' - c( " ne' - 'ort(ne')

> ne'

[1] "ointe : Kico8et" "Benete : #9re8i"":one'c9 M Miore8" "$zr T :on9t"

[5] "


22/96

R as a ectori,ed lan$ua$e


23/96

R as a ectori,ed lan$ua$e(cont.)

perations can #e applied on t/o or more vectors

> n9ec3 - n9ec1 O n9ec2> n9ec3

[1] 1.2 1.+ 11. 114 15. 74 14

Compare a vector /it' a value

> x

[1] -.5+757455 -...734 .243715+ -.5132523 ..32.27> x >= .

[1] #$%! #$%! TR! #$%! TR!

> x1 - x >= .

> x1

[1] #$%! #$%! TR! #$%! TR! Hesting if at least one of t'e vector elements fulNls t'e predicate> x

[1] -.5+757455 -...734 .243715+ -.5132523 ..32.27

> ny(x > .)

[1] TR!


24/96

R as a ectori,ed lan$ua$e(cont.)

Hesting if all t'e vector elements fulNll t'epredicate !function 88(> 88(x > .)

[1] #$%!

> 88(x > -25)[1] TR!

For a c'aracter vector, display t'e num#er ofc'aracters for eac' element

> y

[] "one" "two" "three" "eight"

> nchr(y)

[1] 3 3 5 5

>


25/96

a!in$ ector ele!ents

rovide a name for eac' vector element> n9&ro = c (one = "9n9", two="oi", three="trei",0o9r="Dtr9")

> n9&ro

one two three 0o9r

"9n9" "oi" "trei" "Dtr9"

H'e same result can #e accomplis'ed /it')> n9&ro = c ("9n9", "oi", "trei", "Dtr9")

> n9&ro

[1] "9n9" "oi" "trei" "Dtr9"

> ne'(n9&ro) = c ("one", "two", "three", "0o9r")

> n9&ro

one two three 0o9r

"9n9" "oi" "trei" "Dtr9"


26/96

Descriptie statistics on ectors

A vector !age( containing t'e age of persons

!8a#acoP, -(> ge = c(1,3,5,2,11,,3,,12,3)

Anot'er vector containing t'e /eig't of a#ove people> weight = c(44,53,72,52,5,73,+.,1.4,1.2,+1)

uppose a#ove /eig'ts /ere in U metric system, /e 'adconvert t'em from l#s into &g

> weightg - weight P .454

Compute t'e mean of peopleRs /eig't> en(weight)

[1] 7.+Compute t'e standard deviation of peopleRs /eig't> '(weight)

[1] 2.774

Compute correlation #et/een age and /eig't> cor e wei ht


27/96

Matrices

H/o+dimensional arrays /'ere eac' element 'ast'e same type !numeric,c'aracter, or logical(

Created /it' t'e trix function. Format)> Cyytrix - trix(ector, nrow=n9er&o0&row',

nco8=n9er&o0&co89n', yrow=8ogic8&89e, ine'=8i't( chr&ector&rowne',chr&ector&co8ne'))

◦ vector contains the elements for the matrix

◦ nrow and ncol secify the row and column dimensions

◦ dimnames contains otional row and column labels stored in

character vectors!

◦ byrow indicates whether the matrix should be filled in by row

byrow=TRUE # or by column byrow=FALSE #$ the default is by

column!


28/96

Matrices (cont.)m. is a ? > matri

> 1 - trix(1*2., nrow=5, nco8=4)> 1

[,1] [,2] [,3] [,4]

[1,] 1 + 11 1+

[2,] 2 7 12 17

[3,] 3 13 1

[4,] 4 14 1

[5,] 5 1. 15 2.

m.- is a - - matri, Nlled #y ro/s> ce88' - c(1,2+,24,+)

> rowne' - c("Row1", "Row2")

> co8ne' - c("Go81", "Go82")

> 2 - trix(ce88', nrow=2, nco8=2, yrow=TR!,

O ine'=8i't(rowne', co8ne'))


29/96

Matrices (cont.)

Display m.-

> 2

Go81 Go82

Row 1 1 2+

Row 2 24 +

m.7 is a - - matri, Nlled #y columns

list is a data structure presented after data frame

> 3 - trix(ce88', nrow=2, nco8=2,

yrow=#$%!,


> 3

Go81 Go82

Row 1 1 24

Row 2 2+ +


30/96


31/96

Accesin$ !atri% ele!ents> 1

[,1] [,2] [,3] [,4]

[1,] 1 + 11 1+

[2,] 2 7 12 17

[3,] 3 13 1

[4,] 4 14 1

[5,] 5 1. 15 2.

Display t'e 7rd ro/> 1[3,]

[1] 3 13 1

Display t'e 7rd column

> 1[,3][1] 11 12 13 14 15

Display t'e element at t'e intersection of t'e -ndro/ and t'e 7rd column> 1 [2,3]

[1] 12

A i t i l t


32/96

Accesin$ !atri% ele!ents(cont.)

Display t/o elements from t'e same ro/) m. S-,7Tand m.S-,>T

> 1 [2, c(3,4)]

[1] 12 17

Display t'ree elements from t'e same column)m.S,-T, mS-,-T and m.S7,-T

> 1 [c(1,2, 3), 2]

[1] + 7

Display a Msu#matriM, from m S-,-T to m-S>.>T> 1 [ c(2,3,4), c(2,3,4)]

[,1] [,2] [,3]

[1,] 7 12 17

[2,] 13 1


33/96

Basic statistics on !atri%> 4

co81 co82 co83row1 1 2 3

row2 4 5 +

row3 7

row4 1. 11 12

Compute mean of all t'e cells in matri m.>

> en(4)

[1] +5

Compute mean of all t'e cells on t'e t'ird column

> en(4[,3])

[1] 75

Compute mean of all t'e cells on t'e t'ird ro/

> en(4[3,])[1]


34/96

Basic statistics on !atri% (cont.)

Compute sum of all t'e cells in matri m.>> '9(4)

[1] 7

Compute sum of all t'e cells on t'e t'ird column

> '9(4[,3])

[1] 3.

Compute sum of all t'e cells on t'e t'ird ro/

> '9(4[3,])[1] 24

Compute sum of all t'e cells in matri m.>

> '9(4)

[1] 7


35/96

rowSu!s+colSu!sro/ums calculates t'e sum of t'e cells for eac' ro/ of a

matri> row%9'(4)

row1 row2 row3 row4

+ 15 24 33

colums calculated t'e sums of t'e cells for eac' column of

a matri> co8%9'(4)

co81 co82 co83

22 2+ 3.

ro/;eans*col;eans calculate mean of t'e every ro/*column

> rowCen'(4)

row1 row2 row3 row4

2 5 11

> co8Cen'(4)

co81 co82 co8355 +5 75

Addin$ total rows and colu!ns to


36/96

Addin$ total rows and colu!ns toa !atri%

> 4 co81 co82 co83

row1 1 2 3

row2 4 5 +

row3 7

row4 1. 11 12

Add total column> 4 - cin(4, row%9'(4))

etting t'e name for t'e total column

> co89nne' - co8ne'(4)

> co89nne'[1] "co81" "co82" "co83" ""

> co89nne'[8ength(co89nne')] -

"co8tot8"

> co8ne'(4) - co89nne'

Addi t t l d l t


37/96

Addin$ total rows and colu!ns toa !atri% (cont.)

C'ec& t'e operation> 4

co81 co82 co83 co8tot8

row1 1 2 3 +

row2 4 5 + 15

row3 7 24row4 1. 11 12 33

Add total ro/

> 4 - rin(4, co8%9'(4))

etting t'e name for t'e total column> rowne' - rowne'(4)

> rowne'

[1] "row1" "row2" "row3" "row4" ""

> rowne'[8ength(rowne')] - "rowtot8"

> rowne'(4) - rowne'


38/96

Addin$ total rows and colu!ns toa !atri% (cont.)

C'ec& t'e operationO notice t'e

names of ro/s and columns and t'e

content of last ro/ and column

> 4


row1 1 2 3 +

row2 4 5 + 15

row3 7 24

row4 1. 11 12 33

rowtot8 22 2+ 3. 7


39/96

Arrays

imilar to matrices #ut can 'ave more t'ant/o dimensions

Elements must #e of t'e same type

Created /it' array function)

> yrry - rry(ector,O ien'ion', ine')

◦ vector contains the data for the array

◦ dimensions is a numeric vector giving the maximal

index for each dimension

◦ dimnames % otional list of dimension labels!

Elements in arrays are accessed similar to

t'ose in matrices


40/96


41/96

reate and access arrays (cont.)

display a matri from

elements of A and B for Nrstro/*column of C

> 1 [,,1]

F1 F2 F3

#1 1 3 5

#2 2 4 +

display elements of A for t'e7rd Mro/M of B and -ndro/*columns of C

> 1 [,3,2]

#1 #2

11 12

& display a su#array containg all

elements from Nrst t/oro/s*columns of A, B and C

> 1 [c(1,2),c(1,2),c(1,2)]

, , G1

F1 F2

#1 1 3

#2 2 4

, , G2

F1 F2

#1 7

#2 1.


42/96

Data Fra!es

;ost important data structure in " !at leastfor us(

A data frame is a structure in " t'at 'oldsdata and is similar to t'e datasets found in

standard statistical pac&ages !for eample,A, , and tata( and data#ases

H'e columns are varia#les and t'e ro/s

are o#servationsaria#les can 'ave diPerent types !for

eample, numeric, c'aracter( in t'e samedata frame


43/96

reate an e!pty data ra!e

> 't9ent&gi - t0re('t9ent: = n9eric(),

ne = chrcter(), ge = n9eric(),

'cho8r'hiD = chrcter(),

8&''e''ent = chrcter(),

0in8&gre = n9eric())

> c8''('t9ent&gi)[1] "t0r e"

> 'tr('t9ent&gi)

Qt0r eQ* . o' o0 + ri8e'*

't9ent: * n9 n e * ctor w 6 . 8ee8'*

ge * n9

'cho8r'hiD * ctor w 6 . 8ee8'*

8&''e'' ent* ctor w 6 . 8ee8'*

0in8&gre * n9


44/96

reate a data ra!e ro! ectors

Create t'e vectors

> 't9ent: - c(1, 2, 3, 4, 5)

> ne - c("


45/96


46/96

/seul unctions or displayin$


47/96

/seul unctions or displayin$so!e data ra!e properties

5um#er of o#servations !ro/s(

> nrow('t9ent&gi)[1] 5

5um#er of varia#les !columns(> nco8('t9ent&gi)

[1] +

Bot' t'e num#er of o#servations !ro/s( and varia#les!columns(> i('t9ent&gi)

[1] 5 +

Display t'e names of all t'e varia#les !columns(> ne'('t9ent&gi)

[1] "'t9ent:" "n e" "ge" "'cho8r'hiD""8&''e'' ent" "0in8&gre"

Display t'e names of t'e second, t'ird and fourt'varia#le> ne'('t9ent&gi[2*4])

" " " " " "


48/96


49/96

Selectin$ colu!ns (cont.)elect*display Nrst t/o columns !studentID and

name ( Q ot'er solutions> 't9ent&gi [, c("'t9ent:", "ne")]Using a vector for storing indices of t'e Nrst t/ocolumns

> co8' - c("'t9ent:", "ne")> 't9ent&gi[co8']or

> 't9ent&gi[, ne'('t9ent&gi) ?in? co8']

"eturn MNnalKgradeM varia#le !column( as a vector> 't9ent&gi0in8&gre[1] .. 45 75 .. +..or ... ee on t'e net slide


50/96

Selectin$ colu!ns (cont.)

"eturn MNnalKgradeM varia#le !column( as a vector!cont.(> 't9ent&gi[ , +]or> 't9ent&gi[ , "0in8&gre"]

"eturn MNnalKgradeM varia#le !column( as a one+columndata frame> 't9ent&gi[ , "0in8&gre", roD=#$%!]

0in8&gre

1 ..

2 45

3 75

4 ..

5 +..

S l i


51/96

Selectin$ rows

Display Nrst t/o o#servations !ro/s(

> 't9ent&gi [1*2,] 't9ent: n e ge 'cho8r'hiD

1 1


52/96

attach unctionattach adds t'e data frame to t'e " searc' pat'

> 'erch() [1] "B8o8!n" "too8'*r't9io"[3] "Dcge*'tt'" "Dcge*grDhic'"[5] "Dcge*greice'" "Dcge*9ti8'"[7] "Dcge*t'et'" "Dcge* etho'"[] "#9to8o'" "Dcge*'e"%'en a varia#le name is encountered, data

frames in t'e searc' pat' are c'ec&ed in order tolocate t'e varia#le.

Commands /it'out attac'> 't9ent&gi0in8&gre> t8e ('t9ent&gi8&''e''ent,'t9ent&gi0in8&gre)

> '9ry('t9ent&gi0in8&gre)


53/96

attach s. with H'e same commands using attach

> ttch('t9ent&gi)> 0in8&gre> t8e (8&''e''ent, 0in8&gre)> '9ry(0in8&gre)> D8ot(ge, 0in8&gre)

detach removes an o#ects from t'e searc' pat'> etch('t9ent&gi)

It is advisa#le to use with instead of attach)> with ('t9ent&gi, 0in8&gre)> with ('t9ent&gi, t8e (8&''e''ent,0in8&gre))> with ('t9ent&gi, D8ot(8&''e''ent,

0in8&gre) )


54/96

ase (row) identi'ers

Act li&e primary*uniue &eys in relational ta#les

Can #e speciNed #y rowna!e option /it'in t'edata.ra!e function

%e allocate ne/ values for studentID !to avoidconfusion /it' ro/ num#ers(O t'e remainingvectors are identical

> 't9ent: - c(1..1, 1..2, 1..3, 1..4,1..5)> ne - c("


55/96

ase (row) identi'ers (cont.)A !slig'tly( ne/ version of t'e data frame)

> 't9ent&gi - t0re('t9ent:, ne,ge,O 'cho8r'hiD, 8&''e''ent,O 0in8&gre, rowne' = 't9ent:)student0D is t'e varia#le to use in la#eling cases

on various printouts and grap'ics produced /it'".

display t'e name of t'e ro/s !o#servations(> rowne'('t9ent&gi)

[1] "1..1" "1..2" "1..3" "1..4" "1..5"> 't9ent&gi 't9ent: n e ge 'cho8r'hiD 8&''e'' ent

1..1 1..1


56/96

ase (row) identi'ers (cont.)display t'e name of t'e ro/s !o#servations(

> rowne'('t9ent&gi)[1] "1..1" "1..2" "1..3" "1..4" "1..5"

5otice t'e leftmost column of t'e data framedisplay

> 't9ent&gi 't9ent: n e ge 'cho8r'hiD 8&''e'' ent1..1 1..1


57/96

ase (row) identi'ers (cont.)Display t'e o#servation !ro/( corresponding to

student 0anos 1. Adriana using 'er caseidentiNer !M-M(> 't9ent&gi["1..2",] 't9ent: n e ge 'cho8r'hiD 8&''e'' ent

1..2 1..2 :no' N #rin 1 %t9i91 orte ine

0in8&gre

1..2 45

Display t'e o#servations corresponding tostudents Ianos %. Adriana and op . Ion usingt'eir case identiNer !M-M and M?M(

> 't9ent&gi[c("1..2", "1..5"),] 't9ent: n e ge 'cho8r'hiD 8&''e'' ent

1..2 1..2 :no' N #rin 1 %t9i91 orte ine

1..5 1..5


58/96

Factors (reprise) In presentation 23a, varia#les /ere descri#ed as

nominal, ordinal, interval, and ratioo!inal varia#les are categorical, /it'out an

implied order. Eamples) ;aritaltatus, e, Go#,;asterrogramme

4rdinal varia#les imply order #ut not amount.Eamples) tatus !poor, improved, ecellent (,@a#Assessment !sla#, #ine, foarteBine, ecelent(

0nteral and Ratio varia#les can ta&e on any

value /it'in some range, and #ot' order andamount are implied. Eamples) @iterser8m,$eig't, %eig't, Final2rade !/it' decimals(

Categorical !nominal( and ordered categorical

!ordinal( varia#les are called actors.

Function factor


59/96

Function factor Factors determine 'o/ data /ill #e analyzed and

presented visually H'e function actor() stores t'e categorical

values as a vector of integers in t'e range S... 5 T!/'ere 5 is t'e num#er of uniue values in t'enominal varia#le(, and an internal vector ofc'aracter strings !t'e original values( mapped tot'ese integers

Initially vector sc'olars'ip is a nominal varia#le> 'cho8r'hiD - c("%oci8", "%t9i91",

"%t9i92", O "Cerit", "%t9i91") 5o/ it /ill #e converted into a factor)> 'cho8r'hiD&0 - 0ctor('cho8r'hiD)> 'cho8r'hiD&0

[1] %oci8 %t9i91 %t9i92 C erit %t9i91$ee8'* C erit %oci8 %t9i91 %t9i92


60/96

Factors in data ra!es


61/96

Factors in data ra!es

"e+create t'e data frame using factors

> 't9ent: - c(1..1, 1..2, 1..3, 1..4, 1..5)> ne - c("


62/96

Factors in data ra!es (cont.)Anot'er version of t'e data frame

> 't9ent&gi - t0re(ne, ge,'cho8r'hiD,O 8&''e''ent, 0in8&gre,O rowne' = 't9ent:)

Display t'e structure of t'e data frame> 'tr('t9ent&gi)Qt0r eQ*5 o' o0 5 ri8e'* n e * ctor w 6 5 8ee8' "Fg : C ri",* 52 3 1 4 ge * n9 23 1 21 22 31 'cho8r'hiD * ctor w 6 4 8ee8' "C erit","%oci8",* 2 34 1 3 8&''e'' ent* ; r0ctor w 6 4 8ee8'"%8" "Fine" * 2 3 4 2 1

0in8&gre * n9 45 75 +

Factors in data ra!es (cont )


63/96

Factors in data ra!es (cont.)Basic statistics a#out varia#les in data frame

> '9ry('t9ent&gi) n e ge 'cho8r'hiD Fg : C ri *1 C in *1. C erit *1:no' N #rin *1 1't L 9*21. %oci8 *1Jocz M :o'e0 *1 C ein *22. %t9i91*2


64/96

Factors and alue la"els

> Dtient: - c(1, 2, 3, 4)

> ge - c(25, 34, 2, 52)> iete' - c("TyDe1", "TyDe2", "TyDe1","TyDe1")> 'tt9' - c("


65/96

Factors and alue la"els (cont.)

For $ender, la#els !instead of of values( are displayed

> Dtientt Dtient: ge iete' 'tt9' gener1 1 25 TyDe1


66/96


67/96


68/96

Matrices and lists


69/96

Matrices and lists

;atri dimension names !dimnames( o#ect is a list

> 3 - trix(ce88', nrow=2, nco8=2,O yrow=#$%!,


> 3

Go81 Go82

Row1 1 24

Row2 2+ +

> ine'(3)

[[1]]

[1] "Row1" "Row2"[[2]]

[1] "Go81" "Go82"

> 9n8i't(ine'(3))

[1] "Row1" "Row2" "Go81" "Go82"

reatin$ and displayin$ si!ple lists


70/96

reatin$ and displayin$ si!ple lists

Create t/o simple lists

> 8i't1 = 8i't ("9n9", "oi", "trei")

> 8i't2 = 8i't( c("oi", "trei", "Dtr9"))

izualizing lists

> 8i't1

[[1]]

[1] "9n9"

[[2]]

[1] "oi"

[[3]]

[1] "trei"

> 8i't2

[[1]]

reate a !ore co!ple% list


71/96

reate a !ore co!ple% listlist.: contains t/o previous lists, a vector !seuence( and a dataframe)

> 8i't3 = 8i't (8i't1, 8i't2, 3*7, Dtientt)> 8i't3

[[1]]

[[1]][[1]]

[1] "9n9"

[[1]][[2]]

[1] "oi"[[1]][[3]]

[1] "trei"

[[2]]

[[2]][[1]]

[1] "oi" "trei" "Dtr9"

[[3]][1] 3 4 5 + 7

[[4]]

Dtient: ge iete' 'tt9' gener

1 1 25 TyDe1


72/96

reate a !ore co!ple% list (cont.)

Display t'e structure of list.:)> 'tr(8i't3)

$i't o0 4

*$i't o0 3

* chr "9n9"

* chr "oi"

* chr "trei" *$i't o0 1

* chr [1*3] "oi" "trei" "Dtr9"

* int [1*5] 3 4 5 + 7

*Qt0reQ* 4 o' o0 5 ri8e'*

Dtient:* n9 [1*4] 1 2 3 4 ge * n9 [1*4] 25 34 2 52

iete' * ctor w6 2 8ee8' "TyDe1","TyDe2"* 1 2 1 1

'tt9' * ;r0ctor w6 3 8ee8'"!xce88ent"":Droe"* 3 2 1 3

gener * ctor w6 2 8ee8' "8e","0e8e"* 1 2 2 1

Accessin$ list co!ponents


73/96

Accessin$ list co!ponents

Display t'e num#er of o#ects in a list> 8ength(8i't3)

[1] 4

Access t'e Nrst o#ect of t'e list> 8i't3[[1]]

[[1]][1] "9n9"

[[2]]

[1] "oi"

[[3]]

[1] "trei"

> c8''(8i't3[[1]])

[1] "8i't"

Accessin$ list co!ponents (cont)


74/96

Accessin$ list co!ponents (cont)

Access t'e second component of t'e list

> 8i't3[[2]][[1]]

[1] "oi" "trei" "Dtr9"

> c8''(8i't3[[2]])

[1] "8i't"

... and t'e fourt' component> 8i't3[[4]]

Dtient: ge iete' 'tt9' gener

1 1 25 TyDe1


75/96

6ist co!ponent attri"utes+na!es

Function na!es display t'e names of

designated components of a list

H'e Nrst o#ect of list.: is a list /'osecomponents 'ave no name)

> ne'(8i't3[[1]])

K$$

H'e fourt' o#ect of list.: is a data framecalled patientdataO t'is data frame 'ave fourvaria#les !columns( /'ose names can #edisplayed /it' function na!es)

> ne'(8i't3[[4]])

[1] "Dtient:" "ge" "iete'" "'tt9'"

"gener"

Accessin$ co!ponents within co!ponents


76/96

Accessin$ co!ponents within co!ponents

Display t'e t'ird o#ect /it'in t'e Nrst component in list.:> 8i't3[[1]][[3]]

[1] "trei"

Display, in t'e data frame patientdata !t'e data frame ist'e >t' component of t'e list( t'e values of column a$e !t'iscolumn is t'e -nd of t'e data frame(

8i't3[[4]][, 2] or > 8i't3[[4]][, "ge"]

[1] 25 34 2 52Display a$e as a column !not a vector(> 8i't3[[4]][, "ge", roD=#$%!]

ge

1 25

2 34

3 2

4 52

Display age of t'e t'ird patient> 8i't3[[4]][, 2][3]

> 8i't3[[4]][, "ge", roD=#$%!]ge[3]

[1] 2


77/96

/ni-di!ensional ta"les


78/96

/ni di!ensional ta"lesCreate a ta#le /it' freuencies of scholarship in data frame

student$i

> t8e1 - with('t9ent&gi, t8e('cho8r'hiD))> t8e1

'cho8r'hiD

Cerit %oci8 %t9i91 %t9i92

1 1 2 1Display structure of ta#le.

> 'tr(t8e1)

Qt8eQ int [1*4(1)] 1 1 2 1

- ttr(P, "ine'")=$i't o0 1

'cho8r'hiD* chr [1*4] "Cerit" "%oci8" "%t9i91""%t9i92"

> c8''(t8e1)[1] "t8e"

Unidimensional ta#les are vectors /it' la#eled elements !eac'

elementRs la#el is a value of t'e attri#ute used in function ta"le(

> ne'(t8e1)

[1] "Cerit" "%oci8" "%t9i91" "%t9i92"

Access+display uni-di!ensional ta"les


79/96

+ p y

ta"les.* is not a data frame, so /e cannot ualify t'e varia#le using

...> t8e1Cerit!rror in t8e1Cerit * oDertor i' in8i 0or toic ector'

... #ut /e can access /it' vector indices> t8e1[1]

Cerit

1... or list indices> t8e1[[1]]

[1] 1

Display #ot' la#el and t'e of t'e 7rd element in ta#le ta"le.*)

> t8e1[3]%t9i91

2

... or

> 9n8i't(t8e1)[3]

%t9i91

2


80/96

Bi-di!ensional ta"les


81/96

Bi di!ensional ta"les

imilar to pivot ta#les in Ecel

Create a contingency !pivot( ta#le /it' freuencies ofscholarship #y la"assess!ent> t8e2 - with('t9ent&gi, t8e('cho8r'hiD, 8&''e''ent))

> t8e2

8&''e'' ent

'cho8r'hiD %8 Fine orte ine !xce8ent

C erit . 1 . . %oci8 . 1 . .

%t9i91 1 . 1 .

%t9i92 . . . 1

tructure of ta"le.3

> 'tr(t8e2) Qt8eQ int [1*4, 1*4] . . 1 . 1 1 . . . .

- ttr(P, "i n e'")= $i't o0 2

'cho8r'hiD * chr [1*4] "C erit" "%oci8" "%t9i91" "%t9i92"

8&''e'' ent* chr [1*4] "%8" "Fine" "orte ine" "!xce8ent"

> c8''(t8e2)

[1] "t8e"

Accessin$ "i-di!ensional ta"les


82/96

ccess $ " d e s o a a" es

Any cell can #e accessed using indices of ro/ and column...

> t8e2[1,2]

[1] 1

... or t'e names*la#els

> t8e2["Cerit", "Fine"]

[1] 1

Display t'e second column !associated /it' value Bine of

la"assess!ent( as a vector using t'e inde !-(...

> t8e2[, 2]

C erit %oci8 %t9i91 %t9i92

1 1 . .

... or t'e name of t'e column !Bine(

> t8e2[, "Fine"]

C erit %oci8 %t9i91 %t9i92

1 1 . .

Accessin$ "i-di!ensional ta"les (cont )


83/96

Accessin$ "i-di!ensional ta"les (cont.)

imilarly, one can access individual !or group of( ro/s

Access particular ro/s and columns in a ta#le

> t8e2[c("Cerit", "%t9i91"), c("%8", "!xce8ent")]

8&''e'' ent

'cho8r'hiD %8 !xce8ent

C erit . .

%t9i91 1 .

Tri-di!ensional ta"les


84/96

Create a t'ree+dimensional ta#le /it' freuencies of scholarship #y

la"assess!ent #y 'nal$rade

> t8e3 - with('t9ent&gi, t8e('cho8r'hiD, 8&''e''ent,0in8&gre))

Display ta"le.:> t8e3

, , 0in8&gre = +

8&''e'' ent


C erit . . . .

%oci8 . . . .

%t9i91 1 . . .

%t9i92 . . . .

, , 0in8&gre =

8&''e'' ent


C erit . 1 . .

%oci8 . 1 . .

%t9i91 . . . .

%t9i92 . . . .

Tri-di!ensional ta"les (cont.)


85/96

( )

Display ta"le.: (cont.)

, , 0in8&gre = 45

8&''e'' ent


C erit . . . .

%oci8 . . . . %t9i91 . . 1 .

%t9i92 . . . .

, , 0in8&gre = 75

8&''e'' ent


C erit . . . .

%oci8 . . . .

%t9i91 . . . .

%t9i92 . . . 1

ta"le


86/96

ta"le improves t'e display of t'ree+dimensional ta#les> 0t8e(t8e3)

0in8&gre + 45 75'cho8r'hiD 8&''e'' ent

C erit %8 . . . .

Fine . 1 . .

orte ine . . . .

!xce8ent . . . .

%oci8 %8 . . . .

Fine . 1 . .

orte ine . . . .

!xce8ent . . . .

%t9i91 %8 1 . . .

Fine . . . . orte ine . . 1 .

!xce8ent . . . .

%t9i92 %8 . . . .

Fine . . . .

orte ine . . . .

!xce8ent . . . 1

Accessin$ three-di!ensional ta"les


87/96

Accessin$ three di!ensional ta"les

Any cell can #e accessed using indices of t'e t'ree aes...

> t8e3[3, 3, 3][1] 1

... or t'e names*la#els> t8e3["%t9i92", "!xce8ent", "75"][1] 1

Display, as an one+dimensional ta#le, t'e values of t'e

la"assess!ent /'ic' corespond to value Studiu2 !>t'( of

scholarship and t'e value 9.75 !>t'( of 'nal$rade

◦ one can use the indexes !!!

> t8e3[4, , 4] %8 Fine orte ine !xce8ent. . . 1

◦ !!! or the label(names

> t8e3[ "%t9i92", , "75" ] %8 Fine orte ine !xce8ent

. . . 1

Accessin$ three-di!ensional ta"les (cont.)


88/96

Accessin$ three di!ensional ta"les (cont.)

Display, as a #i+dimensional ta#le, t'e values of t'e Nrst

!scholarship( and t'e t'ird !'nal$rade( aes associated /it't'e >t' value !Excelent ( of t'e second ais !la"assess!ent(

◦ one can use the index!!!

> t8e3[, 4, ] 0in8&gre

'cho8r'hiD + 45 75 C erit . . . .

%oci8 . . . .

%t9i91 . . . .

%t9i92 . . . 1

◦ !!! or the label(name

> t8e3[, "!xce8ent", ] 0in8&gre

'cho8r'hiD + 45 75

C erit . . . .

%oci8 . . . .

%t9i91 . . . .

%t9i92 . . . 1


89/96

Built-in datasets


90/96

Built in datasets

ome datasets are availa#le in #ase !core( " !e.g. fait'ful(

> he(0ith098, 3) er9Dtion' w iting

1 3+.. 7

2 1.. 54

3 3333 74

;ost data sets are availa#le in pac&ages !e.g. ggplot-, vcd,...(

In most cases, data sets are stored as data frames, e.g.

t'e dataset !oies from pac&age $$plot3

Every pac&age must #e installed !once per computer(> in't88Dcge'("ggD8ot2")

After installation, a pac&age must #e loaded !once for

every "tudio session(

> 8irry(ggD8ot2)

Built-in datasets (cont.)


91/96

Built in datasets (cont.)

Display t'e structure of dataset !oies

> 'tr(oie')Qt0r eQ*57 o' o0 24 ri8e'*

tit8e * chr "" "1... To9chow n" "21 y ; nce C onth" "4.,..."

yer * int 171 13 141 1+ 175 2... 2..22..2 17 117

8ength * int 121 71 7 7. 71 1 3 25 7 +1

9get * int K# K# K# K# K# K# K# K# K# K#

rting * n9 +4 + 2 2 34 43 53 +7 ++ +

ote' * int 34 2. 5 + 17 45 2.. 24 1 51 r1 * n9 45 . . 145 245 45 45 45 45 45

r2 * n9 45 145 . . 45 45 . 45 45 .

r3 * n9 45 45 . . . 45 45 45 45 45

Built-in dataset stored as ta"le


92/96

Built in dataset stored as ta"leData set ;airyeolor in pac&age cd is stored as

t'ree+dimensional ta#le !httD*66crn9'r-DroEectorg6w e6Dcge'6c!xtr6ignette'6c-

t9tori8D0)> in't88Dcge'("c")

> 8irry(c)

> he(Hir!yeGo8or)

[1] 32 53 1. 3 11 5.

> 'tr(Hir!yeGo8or)

t8e [1*4, 1*4, 1*2] 32 53 1. 3 11 5. 1. 3. 1. 25

- ttr(P, "i n e'")= $i't o0 3 Hir* chr [1*4] "F8c" "Frow n" "Re" "F8on"

!ye * chr [1*4] "Frow n" "F89e" "Hze8" "Breen"

%ex * chr [1*2] "C 8e" "e 8e"

> c8''(Hir!yeGo8or)

[1] "t8e"

8ac5a$e datasets


93/96

8ac5a$e datasets" 'as a special pac&age called datasets

> 8irry(t'et')function data displays all t'e datasets in t'is pac&age> t()

isualize all t'e data sets availa#le in all pac&ages)

> t(Dcge = Dcge'(88i88e =TR!))

Display t'e datasets availa#le in pac&age $$plot3> try(t(Dcge = "ggD8ot2") )

...or> t(Dcge = "ggD8ot2")re'98t'

A list !made in --( of all datasets in " is availa#le at

'ttp)**///.pu#lic.iastate.edu*W'ofmann*data in r sor

http://www.public.iastate.edu/~hofmann/data_in_r_sortable.htmlhttp://www.public.iastate.edu/~hofmann/data_in_r_sortable.htmlhttp://www.public.iastate.edu/~hofmann/data_in_r_sortable.html


94/96

Data structures conersion (cont.)


95/96

Data structures conersion (cont.)Convert matri !. &to&01 - 't0re(4)> &to&01


row1 1 2 3 +

row2 4 5 + 15

row3 7 24

row4 1. 11 12 33

rowtot8 22 2+ 3. 7

> 'tr(&to&01)

Qt0reQ* 5 o' o0 4 ri8e'* co81 * n9 1 4 7 1. 22

co82 * n9 2 5 11 2+

co83 * n9 3 + 12 3.

co8tot8* n9 + 15 24 33 7

Data structures conersion (cont.)


96/96

Data structures conersion (cont.)Convert a ta#le into a data frame> t8e&to&t0re =t0re(9n8i't(Hir!yeGo8or))

> he(t8e&to&t0re, 3)

Hir !ye %ex re/

1 F8c Frown C8e 32

2 Frown Frown C8e 53

3 Re Frown C8e 1.

Convert a list into a data frame> 0 - t0re(trix(9n8i't(8i't1), nrow=132,

O yrow=T))

> he(0,3) trix9n8i't8i't1nrow132yrowT

1 9n9

2 oi

Documents

02b Data Structures Datasets