Week 1 Homework

Question 1

# a)
seq(112,200,by=2)

 [1] 112 114 116 118 120 122 124 126 128 130 132 134 136 138 140 142 144 146 148
[20] 150 152 154 156 158 160 162 164 166 168 170 172 174 176 178 180 182 184 186
[39] 188 190 192 194 196 198 200

# b)
seq(110,50,by=-10)

[1] 110 100  90  80  70  60  50

# c)
seq(1,5,length.out=1000)

   [1] 1.000000 1.004004 1.008008 1.012012 1.016016 1.020020 1.024024 1.028028
   [9] 1.032032 1.036036 1.040040 1.044044 1.048048 1.052052 1.056056 1.060060
  [17] 1.064064 1.068068 1.072072 1.076076 1.080080 1.084084 1.088088 1.092092
  [25] 1.096096 1.100100 1.104104 1.108108 1.112112 1.116116 1.120120 1.124124
  [33] 1.128128 1.132132 1.136136 1.140140 1.144144 1.148148 1.152152 1.156156
  [41] 1.160160 1.164164 1.168168 1.172172 1.176176 1.180180 1.184184 1.188188
  [49] 1.192192 1.196196 1.200200 1.204204 1.208208 1.212212 1.216216 1.220220
  [57] 1.224224 1.228228 1.232232 1.236236 1.240240 1.244244 1.248248 1.252252
  [65] 1.256256 1.260260 1.264264 1.268268 1.272272 1.276276 1.280280 1.284284
  [73] 1.288288 1.292292 1.296296 1.300300 1.304304 1.308308 1.312312 1.316316
  [81] 1.320320 1.324324 1.328328 1.332332 1.336336 1.340340 1.344344 1.348348
  [89] 1.352352 1.356356 1.360360 1.364364 1.368368 1.372372 1.376376 1.380380
  [97] 1.384384 1.388388 1.392392 1.396396 1.400400 1.404404 1.408408 1.412412
 [105] 1.416416 1.420420 1.424424 1.428428 1.432432 1.436436 1.440440 1.444444
 [113] 1.448448 1.452452 1.456456 1.460460 1.464464 1.468468 1.472472 1.476476
 [121] 1.480480 1.484484 1.488488 1.492492 1.496496 1.500501 1.504505 1.508509
 [129] 1.512513 1.516517 1.520521 1.524525 1.528529 1.532533 1.536537 1.540541
 [137] 1.544545 1.548549 1.552553 1.556557 1.560561 1.564565 1.568569 1.572573
 [145] 1.576577 1.580581 1.584585 1.588589 1.592593 1.596597 1.600601 1.604605
 [153] 1.608609 1.612613 1.616617 1.620621 1.624625 1.628629 1.632633 1.636637
 [161] 1.640641 1.644645 1.648649 1.652653 1.656657 1.660661 1.664665 1.668669
 [169] 1.672673 1.676677 1.680681 1.684685 1.688689 1.692693 1.696697 1.700701
 [177] 1.704705 1.708709 1.712713 1.716717 1.720721 1.724725 1.728729 1.732733
 [185] 1.736737 1.740741 1.744745 1.748749 1.752753 1.756757 1.760761 1.764765
 [193] 1.768769 1.772773 1.776777 1.780781 1.784785 1.788789 1.792793 1.796797
 [201] 1.800801 1.804805 1.808809 1.812813 1.816817 1.820821 1.824825 1.828829
 [209] 1.832833 1.836837 1.840841 1.844845 1.848849 1.852853 1.856857 1.860861
 [217] 1.864865 1.868869 1.872873 1.876877 1.880881 1.884885 1.888889 1.892893
 [225] 1.896897 1.900901 1.904905 1.908909 1.912913 1.916917 1.920921 1.924925
 [233] 1.928929 1.932933 1.936937 1.940941 1.944945 1.948949 1.952953 1.956957
 [241] 1.960961 1.964965 1.968969 1.972973 1.976977 1.980981 1.984985 1.988989
 [249] 1.992993 1.996997 2.001001 2.005005 2.009009 2.013013 2.017017 2.021021
 [257] 2.025025 2.029029 2.033033 2.037037 2.041041 2.045045 2.049049 2.053053
 [265] 2.057057 2.061061 2.065065 2.069069 2.073073 2.077077 2.081081 2.085085
 [273] 2.089089 2.093093 2.097097 2.101101 2.105105 2.109109 2.113113 2.117117
 [281] 2.121121 2.125125 2.129129 2.133133 2.137137 2.141141 2.145145 2.149149
 [289] 2.153153 2.157157 2.161161 2.165165 2.169169 2.173173 2.177177 2.181181
 [297] 2.185185 2.189189 2.193193 2.197197 2.201201 2.205205 2.209209 2.213213
 [305] 2.217217 2.221221 2.225225 2.229229 2.233233 2.237237 2.241241 2.245245
 [313] 2.249249 2.253253 2.257257 2.261261 2.265265 2.269269 2.273273 2.277277
 [321] 2.281281 2.285285 2.289289 2.293293 2.297297 2.301301 2.305305 2.309309
 [329] 2.313313 2.317317 2.321321 2.325325 2.329329 2.333333 2.337337 2.341341
 [337] 2.345345 2.349349 2.353353 2.357357 2.361361 2.365365 2.369369 2.373373
 [345] 2.377377 2.381381 2.385385 2.389389 2.393393 2.397397 2.401401 2.405405
 [353] 2.409409 2.413413 2.417417 2.421421 2.425425 2.429429 2.433433 2.437437
 [361] 2.441441 2.445445 2.449449 2.453453 2.457457 2.461461 2.465465 2.469469
 [369] 2.473473 2.477477 2.481481 2.485485 2.489489 2.493493 2.497497 2.501502
 [377] 2.505506 2.509510 2.513514 2.517518 2.521522 2.525526 2.529530 2.533534
 [385] 2.537538 2.541542 2.545546 2.549550 2.553554 2.557558 2.561562 2.565566
 [393] 2.569570 2.573574 2.577578 2.581582 2.585586 2.589590 2.593594 2.597598
 [401] 2.601602 2.605606 2.609610 2.613614 2.617618 2.621622 2.625626 2.629630
 [409] 2.633634 2.637638 2.641642 2.645646 2.649650 2.653654 2.657658 2.661662
 [417] 2.665666 2.669670 2.673674 2.677678 2.681682 2.685686 2.689690 2.693694
 [425] 2.697698 2.701702 2.705706 2.709710 2.713714 2.717718 2.721722 2.725726
 [433] 2.729730 2.733734 2.737738 2.741742 2.745746 2.749750 2.753754 2.757758
 [441] 2.761762 2.765766 2.769770 2.773774 2.777778 2.781782 2.785786 2.789790
 [449] 2.793794 2.797798 2.801802 2.805806 2.809810 2.813814 2.817818 2.821822
 [457] 2.825826 2.829830 2.833834 2.837838 2.841842 2.845846 2.849850 2.853854
 [465] 2.857858 2.861862 2.865866 2.869870 2.873874 2.877878 2.881882 2.885886
 [473] 2.889890 2.893894 2.897898 2.901902 2.905906 2.909910 2.913914 2.917918
 [481] 2.921922 2.925926 2.929930 2.933934 2.937938 2.941942 2.945946 2.949950
 [489] 2.953954 2.957958 2.961962 2.965966 2.969970 2.973974 2.977978 2.981982
 [497] 2.985986 2.989990 2.993994 2.997998 3.002002 3.006006 3.010010 3.014014
 [505] 3.018018 3.022022 3.026026 3.030030 3.034034 3.038038 3.042042 3.046046
 [513] 3.050050 3.054054 3.058058 3.062062 3.066066 3.070070 3.074074 3.078078
 [521] 3.082082 3.086086 3.090090 3.094094 3.098098 3.102102 3.106106 3.110110
 [529] 3.114114 3.118118 3.122122 3.126126 3.130130 3.134134 3.138138 3.142142
 [537] 3.146146 3.150150 3.154154 3.158158 3.162162 3.166166 3.170170 3.174174
 [545] 3.178178 3.182182 3.186186 3.190190 3.194194 3.198198 3.202202 3.206206
 [553] 3.210210 3.214214 3.218218 3.222222 3.226226 3.230230 3.234234 3.238238
 [561] 3.242242 3.246246 3.250250 3.254254 3.258258 3.262262 3.266266 3.270270
 [569] 3.274274 3.278278 3.282282 3.286286 3.290290 3.294294 3.298298 3.302302
 [577] 3.306306 3.310310 3.314314 3.318318 3.322322 3.326326 3.330330 3.334334
 [585] 3.338338 3.342342 3.346346 3.350350 3.354354 3.358358 3.362362 3.366366
 [593] 3.370370 3.374374 3.378378 3.382382 3.386386 3.390390 3.394394 3.398398
 [601] 3.402402 3.406406 3.410410 3.414414 3.418418 3.422422 3.426426 3.430430
 [609] 3.434434 3.438438 3.442442 3.446446 3.450450 3.454454 3.458458 3.462462
 [617] 3.466466 3.470470 3.474474 3.478478 3.482482 3.486486 3.490490 3.494494
 [625] 3.498498 3.502503 3.506507 3.510511 3.514515 3.518519 3.522523 3.526527
 [633] 3.530531 3.534535 3.538539 3.542543 3.546547 3.550551 3.554555 3.558559
 [641] 3.562563 3.566567 3.570571 3.574575 3.578579 3.582583 3.586587 3.590591
 [649] 3.594595 3.598599 3.602603 3.606607 3.610611 3.614615 3.618619 3.622623
 [657] 3.626627 3.630631 3.634635 3.638639 3.642643 3.646647 3.650651 3.654655
 [665] 3.658659 3.662663 3.666667 3.670671 3.674675 3.678679 3.682683 3.686687
 [673] 3.690691 3.694695 3.698699 3.702703 3.706707 3.710711 3.714715 3.718719
 [681] 3.722723 3.726727 3.730731 3.734735 3.738739 3.742743 3.746747 3.750751
 [689] 3.754755 3.758759 3.762763 3.766767 3.770771 3.774775 3.778779 3.782783
 [697] 3.786787 3.790791 3.794795 3.798799 3.802803 3.806807 3.810811 3.814815
 [705] 3.818819 3.822823 3.826827 3.830831 3.834835 3.838839 3.842843 3.846847
 [713] 3.850851 3.854855 3.858859 3.862863 3.866867 3.870871 3.874875 3.878879
 [721] 3.882883 3.886887 3.890891 3.894895 3.898899 3.902903 3.906907 3.910911
 [729] 3.914915 3.918919 3.922923 3.926927 3.930931 3.934935 3.938939 3.942943
 [737] 3.946947 3.950951 3.954955 3.958959 3.962963 3.966967 3.970971 3.974975
 [745] 3.978979 3.982983 3.986987 3.990991 3.994995 3.998999 4.003003 4.007007
 [753] 4.011011 4.015015 4.019019 4.023023 4.027027 4.031031 4.035035 4.039039
 [761] 4.043043 4.047047 4.051051 4.055055 4.059059 4.063063 4.067067 4.071071
 [769] 4.075075 4.079079 4.083083 4.087087 4.091091 4.095095 4.099099 4.103103
 [777] 4.107107 4.111111 4.115115 4.119119 4.123123 4.127127 4.131131 4.135135
 [785] 4.139139 4.143143 4.147147 4.151151 4.155155 4.159159 4.163163 4.167167
 [793] 4.171171 4.175175 4.179179 4.183183 4.187187 4.191191 4.195195 4.199199
 [801] 4.203203 4.207207 4.211211 4.215215 4.219219 4.223223 4.227227 4.231231
 [809] 4.235235 4.239239 4.243243 4.247247 4.251251 4.255255 4.259259 4.263263
 [817] 4.267267 4.271271 4.275275 4.279279 4.283283 4.287287 4.291291 4.295295
 [825] 4.299299 4.303303 4.307307 4.311311 4.315315 4.319319 4.323323 4.327327
 [833] 4.331331 4.335335 4.339339 4.343343 4.347347 4.351351 4.355355 4.359359
 [841] 4.363363 4.367367 4.371371 4.375375 4.379379 4.383383 4.387387 4.391391
 [849] 4.395395 4.399399 4.403403 4.407407 4.411411 4.415415 4.419419 4.423423
 [857] 4.427427 4.431431 4.435435 4.439439 4.443443 4.447447 4.451451 4.455455
 [865] 4.459459 4.463463 4.467467 4.471471 4.475475 4.479479 4.483483 4.487487
 [873] 4.491491 4.495495 4.499499 4.503504 4.507508 4.511512 4.515516 4.519520
 [881] 4.523524 4.527528 4.531532 4.535536 4.539540 4.543544 4.547548 4.551552
 [889] 4.555556 4.559560 4.563564 4.567568 4.571572 4.575576 4.579580 4.583584
 [897] 4.587588 4.591592 4.595596 4.599600 4.603604 4.607608 4.611612 4.615616
 [905] 4.619620 4.623624 4.627628 4.631632 4.635636 4.639640 4.643644 4.647648
 [913] 4.651652 4.655656 4.659660 4.663664 4.667668 4.671672 4.675676 4.679680
 [921] 4.683684 4.687688 4.691692 4.695696 4.699700 4.703704 4.707708 4.711712
 [929] 4.715716 4.719720 4.723724 4.727728 4.731732 4.735736 4.739740 4.743744
 [937] 4.747748 4.751752 4.755756 4.759760 4.763764 4.767768 4.771772 4.775776
 [945] 4.779780 4.783784 4.787788 4.791792 4.795796 4.799800 4.803804 4.807808
 [953] 4.811812 4.815816 4.819820 4.823824 4.827828 4.831832 4.835836 4.839840
 [961] 4.843844 4.847848 4.851852 4.855856 4.859860 4.863864 4.867868 4.871872
 [969] 4.875876 4.879880 4.883884 4.887888 4.891892 4.895896 4.899900 4.903904
 [977] 4.907908 4.911912 4.915916 4.919920 4.923924 4.927928 4.931932 4.935936
 [985] 4.939940 4.943944 4.947948 4.951952 4.955956 4.959960 4.963964 4.967968
 [993] 4.971972 4.975976 4.979980 4.983984 4.987988 4.991992 4.995996 5.000000

Question 2

# a)
x<-c(-2,101,6,-17,82,-10,56,4,-35,1200,46,-101,0.1,-5)
x

 [1]   -2.0  101.0    6.0  -17.0   82.0  -10.0   56.0    4.0  -35.0 1200.0
[11]   46.0 -101.0    0.1   -5.0

# b)
length(x) 

[1] 14

# c) 
sum(x<0)

[1] 6

# d) 
y <- sort(x)
y

 [1] -101.0  -35.0  -17.0  -10.0   -5.0   -2.0    0.1    4.0    6.0   46.0
[11]   56.0   82.0  101.0 1200.0

Question 3

# a) Vector, length (miles). 

# b)
median(rivers)

[1] 425

median(rivers)*5280

[1] 2244000

Question 4

# a)
nrow(mtcars)

[1] 32

mtcars[32, ]

            mpg cyl disp  hp drat   wt qsec vs am gear carb
Volvo 142E 21.4   4  121 109 4.11 2.78 18.6  1  1    4    2

# b) automatic
mtcars[ ,9]

 [1] 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 1 1 1 1 1 1 1

sum(mtcars[, 9] == 0)

[1] 19

sum(mtcars[, 9] == 1)

[1] 13

# c) 
mtcars[ ,7]

 [1] 16.46 17.02 18.61 19.44 17.02 20.22 15.84 20.00 22.90 18.30 18.90 17.40
[13] 17.60 18.00 17.98 17.82 17.42 19.47 18.52 19.90 20.01 16.87 17.30 15.41
[25] 17.05 18.90 16.70 16.90 14.50 15.50 14.60 18.60

mtcars_fast<-mtcars[mtcars$qsec<=18, ]
mtcars_fast

                     mpg cyl  disp  hp drat    wt  qsec vs am gear carb
Mazda RX4           21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
Mazda RX4 Wag       21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
Hornet Sportabout   18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2
Duster 360          14.3   8 360.0 245 3.21 3.570 15.84  0  0    3    4
Merc 450SE          16.4   8 275.8 180 3.07 4.070 17.40  0  0    3    3
Merc 450SL          17.3   8 275.8 180 3.07 3.730 17.60  0  0    3    3
Merc 450SLC         15.2   8 275.8 180 3.07 3.780 18.00  0  0    3    3
Cadillac Fleetwood  10.4   8 472.0 205 2.93 5.250 17.98  0  0    3    4
Lincoln Continental 10.4   8 460.0 215 3.00 5.424 17.82  0  0    3    4
Chrysler Imperial   14.7   8 440.0 230 3.23 5.345 17.42  0  0    3    4
Dodge Challenger    15.5   8 318.0 150 2.76 3.520 16.87  0  0    3    2
AMC Javelin         15.2   8 304.0 150 3.15 3.435 17.30  0  0    3    2
Camaro Z28          13.3   8 350.0 245 3.73 3.840 15.41  0  0    3    4
Pontiac Firebird    19.2   8 400.0 175 3.08 3.845 17.05  0  0    3    2
Porsche 914-2       26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2
Lotus Europa        30.4   4  95.1 113 3.77 1.513 16.90  1  1    5    2
Ford Pantera L      15.8   8 351.0 264 4.22 3.170 14.50  0  1    5    4
Ferrari Dino        19.7   6 145.0 175 3.62 2.770 15.50  0  1    5    6
Maserati Bora       15.0   8 301.0 335 3.54 3.570 14.60  0  1    5    8

mtcars_slow<-mtcars[mtcars$qsec>18, ]
mtcars_slow

                mpg cyl  disp  hp drat    wt  qsec vs am gear carb
Datsun 710     22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
Hornet 4 Drive 21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
Valiant        18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1
Merc 240D      24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2
Merc 230       22.8   4 140.8  95 3.92 3.150 22.90  1  0    4    2
Merc 280       19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4
Merc 280C      17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4
Fiat 128       32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1
Honda Civic    30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2
Toyota Corolla 33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1
Toyota Corona  21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1
Fiat X1-9      27.3   4  79.0  66 4.08 1.935 18.90  1  1    4    1
Volvo 142E     21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2

# d) Yes, I would think that faster cars have more horsepower.
mean(mtcars_fast$hp)

[1] 185.6842

mean(mtcars_slow$hp)

[1] 89.69231

plot(mtcars$hp, mtcars$qsec)

Question 5

iris$Species == "setosa"

  [1]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
 [13]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
 [25]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
 [37]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
 [49]  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [61] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [73] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [85] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [97] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
[109] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
[121] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
[133] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
[145] FALSE FALSE FALSE FALSE FALSE FALSE

iris$Species == "virginica"

  [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [13] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [25] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [37] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [49] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [61] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [73] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [85] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [97] FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
[109]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
[121]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
[133]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
[145]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE

setosa_virginica <- iris[(iris$Species == "setosa") ==TRUE | (iris$Species == "virginica") ==TRUE, ]
setosa.virginica_Sepal.Shape <- setosa_virginica$Sepal.Length / setosa_virginica$Sepal.Width
setosa.virginica_Sepal.Shape

  [1] 1.457143 1.633333 1.468750 1.483871 1.388889 1.384615 1.352941 1.470588
  [9] 1.517241 1.580645 1.459459 1.411765 1.600000 1.433333 1.450000 1.295455
 [17] 1.384615 1.457143 1.500000 1.342105 1.588235 1.378378 1.277778 1.545455
 [25] 1.411765 1.666667 1.470588 1.485714 1.529412 1.468750 1.548387 1.588235
 [33] 1.268293 1.309524 1.580645 1.562500 1.571429 1.361111 1.466667 1.500000
 [41] 1.428571 1.956522 1.375000 1.428571 1.342105 1.600000 1.342105 1.437500
 [49] 1.432432 1.515152 1.909091 2.148148 2.366667 2.172414 2.166667 2.533333
 [57] 1.960000 2.517241 2.680000 2.000000 2.031250 2.370370 2.266667 2.280000
 [65] 2.071429 2.000000 2.166667 2.026316 2.961538 2.727273 2.156250 2.000000
 [73] 2.750000 2.333333 2.030303 2.250000 2.214286 2.033333 2.285714 2.400000
 [81] 2.642857 2.078947 2.285714 2.250000 2.346154 2.566667 1.852941 2.064516
 [89] 2.000000 2.225806 2.161290 2.225806 2.148148 2.125000 2.030303 2.233333
 [97] 2.520000 2.166667 1.823529 1.966667