Common Objects - Answers

Preface

Open Rstudio to do the practicals. Note that tasks with * are optional.

R packages

In this practical, a number of R packages are used. The packages used (with versions that were used to generate the solutions) are:

• survival (version: 3.5.7)

R version 4.3.2 (2023-10-31 ucrt)

Dataset

For this practical, we will use the heart and retinopathy data sets from the survival package. More details about the data sets can be found in:

https://stat.ethz.ch/R-manual/R-devel/library/survival/html/heart.html

https://stat.ethz.ch/R-manual/R-devel/library/survival/html/retinopathy.html

Always check your data.

Task 1

Explore the heart and retinopathy data sets - print the first six and last six rows.

Hint 1

Use the functions head(…) and tail(…) to investigate the data set. Replace the dots with the name of the data set.

Solution 1

library(survival)
head(heart)

  start stop event        age      year surgery transplant id
1     0   50     1 -17.155373 0.1232033       0          0  1
2     0    6     1   3.835729 0.2546201       0          0  2
3     0    1     0   6.297057 0.2655715       0          0  3
4     1   16     1   6.297057 0.2655715       0          1  3
5     0   36     0  -7.737166 0.4900753       0          0  4
6    36   39     1  -7.737166 0.4900753       0          1  4

tail(heart)

    start stop event        age        year surgery transplant  id
167     0   21     1   1.834360  6.23408624       0          0  99
168     0   38     0 -12.939083  6.39561944       1          0 100
169    38   39     0 -12.939083  6.39561944       1          1 100
170     0   31     0   1.516769  6.41752225       0          0 101
171     0   11     0  -7.608487  6.47227926       0          0 102
172     0    6     1  -8.684463 -0.04928131       0          0 103

head(retinopathy)

  id laser   eye age     type trt futime status risk
1  5 argon  left  28    adult   1  46.23      0    9
2  5 argon  left  28    adult   0  46.23      0    9
3 14 argon right  12 juvenile   1  42.50      0    8
4 14 argon right  12 juvenile   0  31.30      1    6
5 16 xenon right   9 juvenile   1  42.27      0   11
6 16 xenon right   9 juvenile   0  42.27      0   11

tail(retinopathy)

      id laser   eye age     type trt futime status risk
389 1727 argon right  33    adult   1  49.97      0    9
390 1727 argon right  33    adult   0   2.90      1   10
391 1746 argon right   3 juvenile   1  45.90      0   10
392 1746 argon right   3 juvenile   0   1.43      1   10
393 1749 argon right  32    adult   1  41.93      0    9
394 1749 argon right  32    adult   0  41.93      0    9

Common R Objects

It is important to distinguish the different object in R.

Vectors

Let’s investigate some vectors.

Task 1

View the vectors event and age from the heart data set.

Hint 1

Use the dollar sign to select the variables.

Solution 1

heart$event

  [1] 1 1 0 1 0 1 1 1 0 1 1 1 0 1 0 1 1 0 1 0 1 1 0 1 1 0 1 1 0 1 0 1 0 1 0 1 0 1 0 0 0 1 0 1 1 0 1
 [48] 1 0 1 0 0 0 0 1 0 1 0 1 0 1 0 1 0 0 0 0 1 1 1 0 1 0 1 0 1 1 0 0 0 1 0 1 1 0 1 1 0 1 0 0 1 0 1
 [95] 0 0 0 1 1 1 0 0 0 1 0 1 1 0 1 0 1 0 0 0 1 0 0 0 0 0 1 0 1 1 0 0 1 0 0 0 1 0 0 0 0 0 0 1 0 1 1
[142] 0 0 0 1 0 0 0 1 0 1 1 0 0 0 0 0 1 0 1 0 0 0 0 0 0 1 0 0 0 0 1

heart$age

  [1] -17.15537303   3.83572895   6.29705681   6.29705681  -7.73716632  -7.73716632 -27.21423682
  [8]   6.59548255   2.86926762   2.86926762  -2.65023956  -0.83778234  -5.49760438  -5.49760438
 [15]  -0.01916496  -0.01916496   5.19370294   6.57357974   6.57357974   6.01232033   6.01232033
 [22]   5.81519507   1.44832307   1.44832307 -27.66872005   8.84873374   8.84873374  11.12388775
 [29]   7.27994524   7.27994524  -4.65708419  -4.65708419  -5.21560575  -5.21560575  10.35728953
 [36]  10.35728953   3.80013689   3.80013689 -14.77618070 -14.77618070 -17.46475017 -39.21423682
 [43]   6.02327173   6.02327173   2.43394935  -3.08829569  -3.08829569   6.88569473  16.40793977
 [50]  16.40793977   0.90349076   0.90349076  -7.44695414  -7.44695414  -4.53388090   0.92539357
 [57]   0.92539357  13.50034223  13.50034223  -6.52977413  -6.52977413   2.51882272   2.51882272
 [64]   0.48186174   0.48186174  -2.69678303  -2.69678303 -11.55920602  -4.60780287  -5.42094456
 [71] -11.81656400 -11.81656400   0.61054073   0.61054073  -0.90075291  -0.90075291   8.03559206
 [78] -11.34565366 -11.34565366  -2.11362081  -2.11362081   0.73374401   0.73374401  -6.75154004
 [85]  -0.65708419  -0.65708419  -0.20807666   4.45448323   4.45448323  -9.25667351  -9.25667351
 [92]  -6.73511294   0.01642710   0.01642710  -6.61738535  -6.61738535   1.05407255   1.05407255
 [99]   4.56399726  -8.64613279 -15.34017796 -15.34017796   0.81587953   0.81587953   3.29363450
[106]   3.29363450   5.21286790 -28.44900753 -28.44900753  -2.75975359  -2.75975359  -0.01095140
[113]  -0.01095140   5.00205339   5.00205339  -0.59137577  -0.59137577 -21.27310062 -21.27310062
[120]   8.33127995   8.33127995 -18.83367556 -18.83367556   4.18069815   4.08487337   4.08487337
[127]  -6.88843258   0.70362765   0.70362765   5.78234086   5.78234086  -1.55509925  -1.55509925
[134]   4.89253936   4.89253936 -18.79808350   5.30869268   5.30869268  -5.28131417  -5.28131417
[141]  -0.01916496   0.91991786   0.91991786  -1.74674880  -1.74674880   6.36276523   6.36276523
[148]   3.04722793   3.04722793   4.03285421   4.03285421  -0.40520192  -3.01711157  -3.01711157
[155]  -0.24914442  -0.24914442  -4.15879535  -4.15879535  -7.71800137  -7.71800137 -21.34976044
[162] -21.34976044 -24.38329911 -24.38329911 -19.37029432 -19.37029432   1.83436003 -12.93908282
[169] -12.93908282   1.51676934  -7.60848734  -8.68446270

Task 2

View the vectors eye and risk from the retinopathy data set.

Hint 2

Use the dollar sign to select the variables.

Solution 2

retinopathy$eye

  [1] left  left  right right right right left  left  left  left  right right right right right
 [16] right right right right right left  left  right right left  left  right right right right
 [31] left  left  left  left  right right right right right right left  left  right right right
 [46] right left  left  left  left  right right right right left  left  left  left  left  left 
 [61] left  left  left  left  left  left  left  left  left  left  left  left  right right left 
 [76] left  left  left  right right left  left  right right left  left  right right right right
 [91] left  left  left  left  right right right right right right right right left  left  left 
[106] left  right right left  left  left  left  right right left  left  right right right right
[121] right right left  left  left  left  left  left  left  left  right right left  left  left 
[136] left  right right right right left  left  left  left  right right left  left  left  left 
[151] left  left  left  left  left  left  left  left  right right right right right right left 
[166] left  left  left  left  left  left  left  left  left  right right left  left  left  left 
[181] left  left  right right left  left  right right right right left  left  left  left  right
[196] right left  left  left  left  left  left  left  left  right right right right left  left 
[211] left  left  right right left  left  left  left  left  left  right right left  left  left 
[226] left  left  left  right right left  left  right right left  left  left  left  left  left 
[241] right right left  left  right right left  left  left  left  left  left  left  left  right
[256] right left  left  right right right right right right left  left  left  left  left  left 
[271] left  left  left  left  left  left  right right right right left  left  right right right
[286] right right right right right left  left  right right left  left  right right left  left 
[301] right right right right right right right right left  left  right right left  left  right
[316] right left  left  right right left  left  left  left  right right right right left  left 
[331] right right left  left  right right left  left  left  left  left  left  left  left  right
[346] right right right left  left  right right right right right right right right right right
[361] right right left  left  left  left  left  left  right right left  left  right right right
[376] right left  left  left  left  right right left  left  left  left  left  left  right right
[391] right right right right
Levels: right left

retinopathy$risk

  [1]  9  9  8  6 11 11 11 11  9 10  9  9  8  6  8  9  9 10  9  9  9  9 11 12 11  6  6 10 10  9  9
 [32] 10 12  9  9  9  6  8 11 12  9  9  9 12 10 10 12 11 12  9  9 11  9 11 10 12 11 11 10  9  9  9
 [63] 10  8  9  8  9  9  9 11 11 12 11  8  9  9  9  9 10 12 10  9  8 12 10 12 10 10 11 10 10 10 11
 [94]  9  9  8 10  6  9 12  8  8  9  9  9 10  8  9  9  8 10  9 11 10 10 11  8  9 10  8 10  9  9 10
[125]  9  9  9 10 12 11  9 12  9  8 12 10 10  9  6  9 12 10 11 11  9  6  9 12 12 12  9 12  8  6 11
[156] 12 10  9  8 10 11 11  9 12 12 10  8  8  9 11  9 12 11 11 12  9  9  9 12  9  8  8  9 11 11 11
[187]  9  9 10 12 10 12 10 12 12 12  9 12  9  9  8  6 11 10 10 10  6  8  6 10  6  8 10 10 12 11 10
[218] 12 12 12  9 10 12  9  9  9  9  9  9 10 12 10 11 11 10  9  9 11  8  9 12 12 11  9  9  9  9  9
[249] 11 11 10 11 10 11 10  9  9 10 11 11 12 10  9  9 10  9  9 12 10  9 12 11  9  9 11 12  6 10  8
[280]  8  9  9  9  9  9  9 12 11  9 10 10  9  9  9 10 10 11  8 10  9  9  6 11  9  9 11 10 10 10  9
[311]  6  6 11 11 11 11 10  9  8 12 11 11 11 11  9 10  8 12  9  9  9  8 11  9 11  9  9  9 12 11 10
[342]  9  9  9 12 10 12 11 10  9  9  9  9  9  9 10  8 12  9 10 10 10  9  9  9 12 10 12  6  6 11  9
[373]  9  9 10 12  6  8  9  9 10  8 11 10  8  8 12 11  9 10 10 10  9  9

Task 3

Create a numerical vector that consists of the values: 34, 24, 19, 23, 16. Give the name numbers to this new vector.

Hint 3

Use the c(…) function. Replace the dots with the numbers.

Solution 3

numbers <- c(34, 24, 19, 23, 16)

Task 4

Create a numerical vector that takes the integer values from 1 until 200. Give the name numbers_2 to this new vector.

Hint 4

Use the c(…) function. Replace the dots with the numbers.

Solution 4

numbers_2 <- c(1:200)

Task 5 *

Create a categorical vector that consists of the values: yes, yes, no, no, no, yes. Give the name treatment to this new vector.

Hint 5 *

Use the c(…) function. Replace the dots with the categories.

Solution 5 *

treatment <- c("yes", "yes", "no", "no", "no", "yes")

Matrices and Data Frames

Let’s investigate some matrices and data frames.

Task 1

Create a matrix using the vectors id and age from the heart data set. This matrix should have 2 columns where each column represents each variable.

Hint 1

Use the function matrix(…).

Solution 1

matrix(c(heart$id, heart$age), , 2) 

       [,1]         [,2]
  [1,]    1 -17.15537303
  [2,]    2   3.83572895
  [3,]    3   6.29705681
  [4,]    3   6.29705681
  [5,]    4  -7.73716632
  [6,]    4  -7.73716632
  [7,]    5 -27.21423682
  [8,]    6   6.59548255
  [9,]    7   2.86926762
 [10,]    7   2.86926762
 [11,]    8  -2.65023956
 [12,]    9  -0.83778234
 [13,]   10  -5.49760438
 [14,]   10  -5.49760438
 [15,]   11  -0.01916496
 [16,]   11  -0.01916496
 [17,]   12   5.19370294
 [18,]   13   6.57357974
 [19,]   13   6.57357974
 [20,]   14   6.01232033
 [21,]   14   6.01232033
 [22,]   15   5.81519507
 [23,]   16   1.44832307
 [24,]   16   1.44832307
 [25,]   17 -27.66872005
 [26,]   18   8.84873374
 [27,]   18   8.84873374
 [28,]   19  11.12388775
 [29,]   20   7.27994524
 [30,]   20   7.27994524
 [31,]   21  -4.65708419
 [32,]   21  -4.65708419
 [33,]   22  -5.21560575
 [34,]   22  -5.21560575
 [35,]   23  10.35728953
 [36,]   23  10.35728953
 [37,]   24   3.80013689
 [38,]   24   3.80013689
 [39,]   25 -14.77618070
 [40,]   25 -14.77618070
 [41,]   26 -17.46475017
 [42,]   27 -39.21423682
 [43,]   28   6.02327173
 [44,]   28   6.02327173
 [45,]   29   2.43394935
 [46,]   30  -3.08829569
 [47,]   30  -3.08829569
 [48,]   31   6.88569473
 [49,]   32  16.40793977
 [50,]   32  16.40793977
 [51,]   33   0.90349076
 [52,]   33   0.90349076
 [53,]   34  -7.44695414
 [54,]   34  -7.44695414
 [55,]   35  -4.53388090
 [56,]   36   0.92539357
 [57,]   36   0.92539357
 [58,]   37  13.50034223
 [59,]   37  13.50034223
 [60,]   38  -6.52977413
 [61,]   38  -6.52977413
 [62,]   39   2.51882272
 [63,]   39   2.51882272
 [64,]   40   0.48186174
 [65,]   40   0.48186174
 [66,]   41  -2.69678303
 [67,]   41  -2.69678303
 [68,]   42 -11.55920602
 [69,]   43  -4.60780287
 [70,]   44  -5.42094456
 [71,]   45 -11.81656400
 [72,]   45 -11.81656400
 [73,]   46   0.61054073
 [74,]   46   0.61054073
 [75,]   47  -0.90075291
 [76,]   47  -0.90075291
 [77,]   48   8.03559206
 [78,]   49 -11.34565366
 [79,]   49 -11.34565366
 [80,]   50  -2.11362081
 [81,]   50  -2.11362081
 [82,]   51   0.73374401
 [83,]   51   0.73374401
 [84,]   52  -6.75154004
 [85,]   53  -0.65708419
 [86,]   53  -0.65708419
 [87,]   54  -0.20807666
 [88,]   55   4.45448323
 [89,]   55   4.45448323
 [90,]   56  -9.25667351
 [91,]   56  -9.25667351
 [92,]   57  -6.73511294
 [93,]   58   0.01642710
 [94,]   58   0.01642710
 [95,]   59  -6.61738535
 [96,]   59  -6.61738535
 [97,]   60   1.05407255
 [98,]   60   1.05407255
 [99,]   61   4.56399726
[100,]   62  -8.64613279
[101,]   63 -15.34017796
[102,]   63 -15.34017796
[103,]   64   0.81587953
[104,]   64   0.81587953
[105,]   65   3.29363450
[106,]   65   3.29363450
[107,]   66   5.21286790
[108,]   67 -28.44900753
[109,]   67 -28.44900753
[110,]   68  -2.75975359
[111,]   68  -2.75975359
[112,]   69  -0.01095140
[113,]   69  -0.01095140
[114,]   70   5.00205339
[115,]   70   5.00205339
[116,]   71  -0.59137577
[117,]   71  -0.59137577
[118,]   72 -21.27310062
[119,]   72 -21.27310062
[120,]   73   8.33127995
[121,]   73   8.33127995
[122,]   74 -18.83367556
[123,]   74 -18.83367556
[124,]   75   4.18069815
[125,]   76   4.08487337
[126,]   76   4.08487337
[127,]   77  -6.88843258
[128,]   78   0.70362765
[129,]   78   0.70362765
[130,]   79   5.78234086
[131,]   79   5.78234086
[132,]   80  -1.55509925
[133,]   80  -1.55509925
[134,]   81   4.89253936
[135,]   81   4.89253936
[136,]   82 -18.79808350
[137,]   83   5.30869268
[138,]   83   5.30869268
[139,]   84  -5.28131417
[140,]   84  -5.28131417
[141,]   85  -0.01916496
[142,]   86   0.91991786
[143,]   86   0.91991786
[144,]   87  -1.74674880
[145,]   87  -1.74674880
[146,]   88   6.36276523
[147,]   88   6.36276523
[148,]   89   3.04722793
[149,]   89   3.04722793
[150,]   90   4.03285421
[151,]   90   4.03285421
[152,]   91  -0.40520192
[153,]   92  -3.01711157
[154,]   92  -3.01711157
[155,]   93  -0.24914442
[156,]   93  -0.24914442
[157,]   94  -4.15879535
[158,]   94  -4.15879535
[159,]   95  -7.71800137
[160,]   95  -7.71800137
[161,]   96 -21.34976044
[162,]   96 -21.34976044
[163,]   97 -24.38329911
[164,]   97 -24.38329911
[165,]   98 -19.37029432
[166,]   98 -19.37029432
[167,]   99   1.83436003
[168,]  100 -12.93908282
[169,]  100 -12.93908282
[170,]  101   1.51676934
[171,]  102  -7.60848734
[172,]  103  -8.68446270

Task 2

Create a data frame using the vectors id, type and trt from the retinopathy data set. This data frame should have 3 columns, where each column represents each variable.

Hint 2

Use the function data.frame(…).

Solution 2

data.frame(id = retinopathy$id, type = retinopathy$type, trt = retinopathy$trt) 

      id     type trt
1      5    adult   1
2      5    adult   0
3     14 juvenile   1
4     14 juvenile   0
5     16 juvenile   1
6     16 juvenile   0
7     25 juvenile   1
8     25 juvenile   0
9     29 juvenile   1
10    29 juvenile   0
11    46 juvenile   1
12    46 juvenile   0
13    49 juvenile   1
14    49 juvenile   0
15    56 juvenile   1
16    56 juvenile   0
17    61 juvenile   1
18    61 juvenile   0
19    71    adult   1
20    71    adult   0
21   100    adult   1
22   100    adult   0
23   112    adult   1
24   112    adult   0
25   120    adult   1
26   120    adult   0
27   127    adult   1
28   127    adult   0
29   133    adult   1
30   133    adult   0
31   150 juvenile   1
32   150 juvenile   0
33   167    adult   1
34   167    adult   0
35   176 juvenile   1
36   176 juvenile   0
37   185    adult   1
38   185    adult   0
39   190 juvenile   1
40   190 juvenile   0
41   202 juvenile   1
42   202 juvenile   0
43   214    adult   1
44   214    adult   0
45   220 juvenile   1
46   220 juvenile   0
47   243 juvenile   1
48   243 juvenile   0
49   255 juvenile   1
50   255 juvenile   0
51   264 juvenile   1
52   264 juvenile   0
53   266    adult   1
54   266    adult   0
55   284    adult   1
56   284    adult   0
57   295 juvenile   1
58   295 juvenile   0
59   300    adult   1
60   300    adult   0
61   302 juvenile   1
62   302 juvenile   0
63   315 juvenile   1
64   315 juvenile   0
65   324    adult   1
66   324    adult   0
67   328 juvenile   1
68   328 juvenile   0
69   335 juvenile   1
70   335 juvenile   0
71   342 juvenile   1
72   342 juvenile   0
73   349    adult   1
74   349    adult   0
75   357    adult   1
76   357    adult   0
77   368 juvenile   1
78   368 juvenile   0
79   385 juvenile   1
80   385 juvenile   0
81   396    adult   1
82   396    adult   0
83   405 juvenile   1
84   405 juvenile   0
85   409    adult   1
86   409    adult   0
87   419    adult   1
88   419    adult   0
89   429    adult   1
90   429    adult   0
91   433    adult   1
92   433    adult   0
93   445 juvenile   1
94   445 juvenile   0
95   454 juvenile   1
96   454 juvenile   0
97   468 juvenile   1
98   468 juvenile   0
99   480 juvenile   1
100  480 juvenile   0
101  485 juvenile   1
102  485 juvenile   0
103  491    adult   1
104  491    adult   0
105  503    adult   1
106  503    adult   0
107  515    adult   1
108  515    adult   0
109  522 juvenile   1
110  522 juvenile   0
111  538    adult   1
112  538    adult   0
113  547    adult   1
114  547    adult   0
115  550 juvenile   1
116  550 juvenile   0
117  554 juvenile   1
118  554 juvenile   0
119  557 juvenile   1
120  557 juvenile   0
121  561 juvenile   1
122  561 juvenile   0
123  568 juvenile   1
124  568 juvenile   0
125  572 juvenile   1
126  572 juvenile   0
127  576 juvenile   1
128  576 juvenile   0
129  581    adult   1
130  581    adult   0
131  606 juvenile   1
132  606 juvenile   0
133  610 juvenile   1
134  610 juvenile   0
135  615 juvenile   1
136  615 juvenile   0
137  618 juvenile   1
138  618 juvenile   0
139  624 juvenile   1
140  624 juvenile   0
141  631 juvenile   1
142  631 juvenile   0
143  636 juvenile   1
144  636 juvenile   0
145  645 juvenile   1
146  645 juvenile   0
147  653 juvenile   1
148  653 juvenile   0
149  662 juvenile   1
150  662 juvenile   0
151  664 juvenile   1
152  664 juvenile   0
153  683    adult   1
154  683    adult   0
155  687 juvenile   1
156  687 juvenile   0
157  701 juvenile   1
158  701 juvenile   0
159  706    adult   1
160  706    adult   0
161  717    adult   1
162  717    adult   0
163  722 juvenile   1
164  722 juvenile   0
165  731 juvenile   1
166  731 juvenile   0
167  740 juvenile   1
168  740 juvenile   0
169  749    adult   1
170  749    adult   0
171  757 juvenile   1
172  757 juvenile   0
173  760 juvenile   1
174  760 juvenile   0
175  766    adult   1
176  766    adult   0
177  769 juvenile   1
178  769 juvenile   0
179  772 juvenile   1
180  772 juvenile   0
181  778    adult   1
182  778    adult   0
183  780 juvenile   1
184  780 juvenile   0
185  793    adult   1
186  793    adult   0
187  800    adult   1
188  800    adult   0
189  804    adult   1
190  804    adult   0
191  810 juvenile   1
192  810 juvenile   0
193  815    adult   1
194  815    adult   0
195  832 juvenile   1
196  832 juvenile   0
197  834 juvenile   1
198  834 juvenile   0
199  838    adult   1
200  838    adult   0
201  857 juvenile   1
202  857 juvenile   0
203  866    adult   1
204  866    adult   0
205  887    adult   1
206  887    adult   0
207  903    adult   1
208  903    adult   0
209  910    adult   1
210  910    adult   0
211  920 juvenile   1
212  920 juvenile   0
213  925    adult   1
214  925    adult   0
215  931 juvenile   1
216  931 juvenile   0
217  936 juvenile   1
218  936 juvenile   0
219  945 juvenile   1
220  945 juvenile   0
221  949 juvenile   1
222  949 juvenile   0
223  952 juvenile   1
224  952 juvenile   0
225  962 juvenile   1
226  962 juvenile   0
227  964 juvenile   1
228  964 juvenile   0
229  971    adult   1
230  971    adult   0
231  978 juvenile   1
232  978 juvenile   0
233  983 juvenile   1
234  983 juvenile   0
235  987 juvenile   1
236  987 juvenile   0
237 1002 juvenile   1
238 1002 juvenile   0
239 1017    adult   1
240 1017    adult   0
241 1029    adult   1
242 1029    adult   0
243 1034 juvenile   1
244 1034 juvenile   0
245 1037    adult   1
246 1037    adult   0
247 1042    adult   1
248 1042    adult   0
249 1069    adult   1
250 1069    adult   0
251 1074 juvenile   1
252 1074 juvenile   0
253 1098 juvenile   1
254 1098 juvenile   0
255 1102 juvenile   1
256 1102 juvenile   0
257 1112 juvenile   1
258 1112 juvenile   0
259 1117 juvenile   1
260 1117 juvenile   0
261 1126    adult   1
262 1126    adult   0
263 1135 juvenile   1
264 1135 juvenile   0
265 1145    adult   1
266 1145    adult   0
267 1148    adult   1
268 1148    adult   0
269 1167 juvenile   1
270 1167 juvenile   0
271 1184    adult   1
272 1184    adult   0
273 1191    adult   1
274 1191    adult   0
275 1205 juvenile   1
276 1205 juvenile   0
277 1213 juvenile   1
278 1213 juvenile   0
279 1228    adult   1
280 1228    adult   0
281 1247 juvenile   1
282 1247 juvenile   0
283 1250    adult   1
284 1250    adult   0
285 1253 juvenile   1
286 1253 juvenile   0
287 1267    adult   1
288 1267    adult   0
289 1281    adult   1
290 1281    adult   0
291 1287 juvenile   1
292 1287 juvenile   0
293 1293 juvenile   1
294 1293 juvenile   0
295 1296 juvenile   1
296 1296 juvenile   0
297 1309    adult   1
298 1309    adult   0
299 1312 juvenile   1
300 1312 juvenile   0
301 1317 juvenile   1
302 1317 juvenile   0
303 1321 juvenile   1
304 1321 juvenile   0
305 1333 juvenile   1
306 1333 juvenile   0
307 1347 juvenile   1
308 1347 juvenile   0
309 1361 juvenile   1
310 1361 juvenile   0
311 1366    adult   1
312 1366    adult   0
313 1373 juvenile   1
314 1373 juvenile   0
315 1397    adult   1
316 1397    adult   0
317 1410    adult   1
318 1410    adult   0
319 1413 juvenile   1
320 1413 juvenile   0
321 1425    adult   1
322 1425    adult   0
323 1447 juvenile   1
324 1447 juvenile   0
325 1461    adult   1
326 1461    adult   0
327 1469    adult   1
328 1469    adult   0
329 1480    adult   1
330 1480    adult   0
331 1487    adult   1
332 1487    adult   0
333 1491    adult   1
334 1491    adult   0
335 1499    adult   1
336 1499    adult   0
337 1503    adult   1
338 1503    adult   0
339 1513    adult   1
340 1513    adult   0
341 1524    adult   1
342 1524    adult   0
343 1533    adult   1
344 1533    adult   0
345 1537 juvenile   1
346 1537 juvenile   0
347 1552 juvenile   1
348 1552 juvenile   0
349 1554    adult   1
350 1554    adult   0
351 1562    adult   1
352 1562    adult   0
353 1572    adult   1
354 1572    adult   0
355 1581    adult   1
356 1581    adult   0
357 1585    adult   1
358 1585    adult   0
359 1596 juvenile   1
360 1596 juvenile   0
361 1600 juvenile   1
362 1600 juvenile   0
363 1603 juvenile   1
364 1603 juvenile   0
365 1619    adult   1
366 1619    adult   0
367 1627 juvenile   1
368 1627 juvenile   0
369 1636 juvenile   1
370 1636 juvenile   0
371 1640 juvenile   1
372 1640 juvenile   0
373 1643 juvenile   1
374 1643 juvenile   0
375 1649 juvenile   1
376 1649 juvenile   0
377 1666 juvenile   1
378 1666 juvenile   0
379 1672 juvenile   1
380 1672 juvenile   0
381 1683    adult   1
382 1683    adult   0
383 1688 juvenile   1
384 1688 juvenile   0
385 1705 juvenile   1
386 1705 juvenile   0
387 1717    adult   1
388 1717    adult   0
389 1727    adult   1
390 1727    adult   0
391 1746 juvenile   1
392 1746 juvenile   0
393 1749    adult   1
394 1749    adult   0

Arrays

Let’s investigate some arrays.

Task 1

Create an array that consists of 2 matrices. Matrix 1 will consist of the values 1:4 and matrix 2 will consist of the values 5:8. Both matrices will have 2 columns and 2 rows.

Hint 1

Use the function array(…).

Solution 1

array(data = 1:8, dim = c(2, 2, 2))

, , 1

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

, , 2

     [,1] [,2]
[1,]    5    7
[2,]    6    8

Task 2 *

Give the name ar1 to the previous array. Furthermore, investigate the argument dimnames and change the names of the rows, columns and matrices.

Hint 2 *

Use the function array(…). Check the help page for the dimnames argument. Note that this must be in a list format.

Solution 2 *

ar1 <- array(data = 1:8, dim = c(2, 2, 2), 
             dimnames = list(c("Row1", "Row2"), c("Col1", "Col2"), c("Mat1", "Mat2")))

Lists

Let’s investigate some lists.

Task 1

Create a list using the vectors stop from the heart data set and id, risk from the retinopathy data set. Give the names stop_heart, id_reti and risk_reti.

Hint 1

Use the function list(…).

Solution 1

list(stop_heart = heart$stop, id_reti = retinopathy$id, risk_reti = retinopathy$risk)

$stop_heart
  [1]   50.0    6.0    1.0   16.0   36.0   39.0   18.0    3.0   51.0  675.0   40.0   85.0   12.0
 [14]   58.0   26.0  153.0    8.0   17.0   81.0   37.0 1387.0    1.0   28.0  308.0   36.0   20.0
 [27]   43.0   37.0   18.0   28.0    8.0 1032.0   12.0   51.0    3.0  733.0   83.0  219.0   25.0
 [40] 1800.0 1401.0  263.0   71.0   72.0   35.0   16.0  852.0   16.0   17.0   77.0   51.0 1587.0
 [53]   23.0 1572.0   12.0   46.0  100.0   19.0   66.0    4.5    5.0    2.0   53.0   41.0 1408.0
 [66]   58.0 1322.0    3.0    2.0   40.0    1.0   45.0    2.0  996.0   21.0   72.0    9.0   36.0
 [79] 1142.0   83.0  980.0   32.0  285.0  102.0   41.0  188.0    3.0   10.0   61.0   67.0  942.0
 [92]  149.0   21.0  343.0   78.0  916.0    3.0   68.0    2.0   69.0   27.0  842.0   33.0  584.0
[105]   12.0   78.0   32.0   57.0  285.0    3.0   68.0   10.0  670.0    5.0   30.0   31.0  620.0
[118]    4.0  596.0   27.0   90.0    5.0   17.0    2.0   46.0  545.0   21.0  210.0  515.0   67.0
[131]   96.0   26.0  482.0    6.0  445.0  428.0   32.0   80.0   37.0  334.0    5.0    8.0  397.0
[144]   60.0  110.0   31.0  370.0  139.0  207.0  160.0  186.0  340.0  310.0  340.0   28.0  265.0
[157]    4.0  165.0    2.0   16.0   13.0  180.0   21.0  131.0   96.0  109.0   21.0   38.0   39.0
[170]   31.0   11.0    6.0

$id_reti
  [1]    5    5   14   14   16   16   25   25   29   29   46   46   49   49   56   56   61   61   71
 [20]   71  100  100  112  112  120  120  127  127  133  133  150  150  167  167  176  176  185  185
 [39]  190  190  202  202  214  214  220  220  243  243  255  255  264  264  266  266  284  284  295
 [58]  295  300  300  302  302  315  315  324  324  328  328  335  335  342  342  349  349  357  357
 [77]  368  368  385  385  396  396  405  405  409  409  419  419  429  429  433  433  445  445  454
 [96]  454  468  468  480  480  485  485  491  491  503  503  515  515  522  522  538  538  547  547
[115]  550  550  554  554  557  557  561  561  568  568  572  572  576  576  581  581  606  606  610
[134]  610  615  615  618  618  624  624  631  631  636  636  645  645  653  653  662  662  664  664
[153]  683  683  687  687  701  701  706  706  717  717  722  722  731  731  740  740  749  749  757
[172]  757  760  760  766  766  769  769  772  772  778  778  780  780  793  793  800  800  804  804
[191]  810  810  815  815  832  832  834  834  838  838  857  857  866  866  887  887  903  903  910
[210]  910  920  920  925  925  931  931  936  936  945  945  949  949  952  952  962  962  964  964
[229]  971  971  978  978  983  983  987  987 1002 1002 1017 1017 1029 1029 1034 1034 1037 1037 1042
[248] 1042 1069 1069 1074 1074 1098 1098 1102 1102 1112 1112 1117 1117 1126 1126 1135 1135 1145 1145
[267] 1148 1148 1167 1167 1184 1184 1191 1191 1205 1205 1213 1213 1228 1228 1247 1247 1250 1250 1253
[286] 1253 1267 1267 1281 1281 1287 1287 1293 1293 1296 1296 1309 1309 1312 1312 1317 1317 1321 1321
[305] 1333 1333 1347 1347 1361 1361 1366 1366 1373 1373 1397 1397 1410 1410 1413 1413 1425 1425 1447
[324] 1447 1461 1461 1469 1469 1480 1480 1487 1487 1491 1491 1499 1499 1503 1503 1513 1513 1524 1524
[343] 1533 1533 1537 1537 1552 1552 1554 1554 1562 1562 1572 1572 1581 1581 1585 1585 1596 1596 1600
[362] 1600 1603 1603 1619 1619 1627 1627 1636 1636 1640 1640 1643 1643 1649 1649 1666 1666 1672 1672
[381] 1683 1683 1688 1688 1705 1705 1717 1717 1727 1727 1746 1746 1749 1749

$risk_reti
  [1]  9  9  8  6 11 11 11 11  9 10  9  9  8  6  8  9  9 10  9  9  9  9 11 12 11  6  6 10 10  9  9
 [32] 10 12  9  9  9  6  8 11 12  9  9  9 12 10 10 12 11 12  9  9 11  9 11 10 12 11 11 10  9  9  9
 [63] 10  8  9  8  9  9  9 11 11 12 11  8  9  9  9  9 10 12 10  9  8 12 10 12 10 10 11 10 10 10 11
 [94]  9  9  8 10  6  9 12  8  8  9  9  9 10  8  9  9  8 10  9 11 10 10 11  8  9 10  8 10  9  9 10
[125]  9  9  9 10 12 11  9 12  9  8 12 10 10  9  6  9 12 10 11 11  9  6  9 12 12 12  9 12  8  6 11
[156] 12 10  9  8 10 11 11  9 12 12 10  8  8  9 11  9 12 11 11 12  9  9  9 12  9  8  8  9 11 11 11
[187]  9  9 10 12 10 12 10 12 12 12  9 12  9  9  8  6 11 10 10 10  6  8  6 10  6  8 10 10 12 11 10
[218] 12 12 12  9 10 12  9  9  9  9  9  9 10 12 10 11 11 10  9  9 11  8  9 12 12 11  9  9  9  9  9
[249] 11 11 10 11 10 11 10  9  9 10 11 11 12 10  9  9 10  9  9 12 10  9 12 11  9  9 11 12  6 10  8
[280]  8  9  9  9  9  9  9 12 11  9 10 10  9  9  9 10 10 11  8 10  9  9  6 11  9  9 11 10 10 10  9
[311]  6  6 11 11 11 11 10  9  8 12 11 11 11 11  9 10  8 12  9  9  9  8 11  9 11  9  9  9 12 11 10
[342]  9  9  9 12 10 12 11 10  9  9  9  9  9  9 10  8 12  9 10 10 10  9  9  9 12 10 12  6  6 11  9
[373]  9  9 10 12  6  8  9  9 10  8 11 10  8  8 12 11  9 10 10 10  9  9

Task 2 *

Create a list using the vectors numbers, numbers_2 and treatment. These variables can be taken from the exercise called Vectors. Give the names: numbers, many_numbers and treatment.

Hint 2 *

Use the function list(…).

Solution 2 *

list(numbers = numbers, many_numbers = numbers_2, treatment = treatment)

$numbers
[1] 34 24 19 23 16

$many_numbers
  [1]   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23
 [24]  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46
 [47]  47  48  49  50  51  52  53  54  55  56  57  58  59  60  61  62  63  64  65  66  67  68  69
 [70]  70  71  72  73  74  75  76  77  78  79  80  81  82  83  84  85  86  87  88  89  90  91  92
 [93]  93  94  95  96  97  98  99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115
[116] 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138
[139] 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161
[162] 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184
[185] 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200

$treatment
[1] "yes" "yes" "no"  "no"  "no"  "yes"