Lab Worksheet 4
Part 1: The dplyr pipe
The following questions in Part 1 are from Lab Worksheet 3. Answer these questions again, but this time use the dplyr pipe (%>%) in your answer.
Problem 1: In an in-class exercise, we made the following plot of the Sitka dataset:
# download the sitka data set:
sitka <- read.csv("http://wilkelab.org/classes/SDS348/data_sets/sitka.csv")
head(sitka)## size Time tree treat
## 1 4.51 152 1 ozone
## 2 4.98 174 1 ozone
## 3 5.41 201 1 ozone
## 4 5.90 227 1 ozone
## 5 6.15 258 1 ozone
## 6 4.24 152 2 ozoneggplot(sitka, aes(x = Time, y = size, group = tree)) +
geom_line() +
facet_wrap(~treat)
Now modify the plot so that the line for each tree is colored according to the maximum size of the tree.
sitka_new <-
sitka %>%
group_by(tree) %>%
mutate(max_size = max(size))
ggplot(sitka_new, aes(x = Time, y = size, group = tree, color = max_size)) +
geom_line() +
facet_wrap(~treat)
Problem 2: The package nycflights13 contains information about all flights departing from one of the NY City airports in 2013. In particular, the data table flights lists on-time departure and arrival information for 336,776 individual flights:
library(nycflights13)
flights## # A tibble: 336,776 x 19
## year month day dep_time sched_dep_time dep_delay arr_time
## <int> <int> <int> <int> <int> <dbl> <int>
## 1 2013 1 1 517 515 2 830
## 2 2013 1 1 533 529 4 850
## 3 2013 1 1 542 540 2 923
## 4 2013 1 1 544 545 -1 1004
## 5 2013 1 1 554 600 -6 812
## 6 2013 1 1 554 558 -4 740
## 7 2013 1 1 555 600 -5 913
## 8 2013 1 1 557 600 -3 709
## 9 2013 1 1 557 600 -3 838
## 10 2013 1 1 558 600 -2 753
## # ... with 336,766 more rows, and 12 more variables: sched_arr_time <int>,
## # arr_delay <dbl>, carrier <chr>, flight <int>, tailnum <chr>,
## # origin <chr>, dest <chr>, air_time <dbl>, distance <dbl>, hour <dbl>,
## # minute <dbl>, time_hour <dttm>We would like to collect some information about arrival delays of United Airlines (UA) flights. Do the following: pick all UA departures with non-zero arrival delay and calculate the mean arrival delay for each of the corresponding flight numbers. Which flight had the longest mean arrival delay and how long was that delay?
flights %>%
filter(carrier == "UA" & arr_delay != 0) %>%
group_by(flight) %>%
summarize(mean_delay = mean(arr_delay)) %>%
filter(mean_delay == max(mean_delay))## # A tibble: 1 x 2
## flight mean_delay
## <int> <dbl>
## 1 1510 283Flight 1510 had the longest delay, with an average arrival delay of 283 minutes.
###Part 2: Combining data-frames with dplyr
Problem 1: Invent two simple data sets that allow you explain the difference between the dplyr functions left_join() and inner_join(). Explain which features of your data sets affect the behavior of these two functions.
# data set 1
d1 <- read.table(text = "
label number1
A 1
B 2
C 4", head = T)
# data set 2
d2 <- read.table(text = "
label number2
A 2
C 4
D 6
", head = T)
d1## label number1
## 1 A 1
## 2 B 2
## 3 C 4d2## label number2
## 1 A 2
## 2 C 4
## 3 D 6left_join(d1, d2)## Joining, by = "label"## Warning: Column `label` joining factors with different levels, coercing to
## character vector## label number1 number2
## 1 A 1 2
## 2 B 2 NA
## 3 C 4 4inner_join(d1, d2)## Joining, by = "label"## Warning: Column `label` joining factors with different levels, coercing to
## character vector## label number1 number2
## 1 A 1 2
## 2 C 4 4We join the two data sets by label. left_join() finds all rows in the second data set that match to rows in the first data set. Therefore, we don’t get a value for number2 corresponding to label B. By contrast, inner_join() only keeps the matching rows that exist in both data sets. Therefore, the resulting table has only two rows, one for label A and one for label C.
Problem 2: I have split the sitka data set into two data-frames. First, look up the documentation for the bind_rows function. What does bind_rows do? Next, use bind_rows to combine sitka1 and sitka2 back into a single data-frame.
The bind_rows function adds rows from one data-frame to another as long as both data-frames have the same number of columns and identical column names.
sitka1 <- sitka[1:100, ]
sitka2 <- sitka[101:395, ]
head(sitka1)## size Time tree treat
## 1 4.51 152 1 ozone
## 2 4.98 174 1 ozone
## 3 5.41 201 1 ozone
## 4 5.90 227 1 ozone
## 5 6.15 258 1 ozone
## 6 4.24 152 2 ozonehead(sitka2)## size Time tree treat
## 101 4.04 152 21 ozone
## 102 4.64 174 21 ozone
## 103 4.86 201 21 ozone
## 104 5.09 227 21 ozone
## 105 5.25 258 21 ozone
## 106 3.53 152 22 ozonesitka_combined <- bind_rows(sitka1, sitka2)
sitka_combined## size Time tree treat
## 1 4.51 152 1 ozone
## 2 4.98 174 1 ozone
## 3 5.41 201 1 ozone
## 4 5.90 227 1 ozone
## 5 6.15 258 1 ozone
## 6 4.24 152 2 ozone
## 7 4.20 174 2 ozone
## 8 4.68 201 2 ozone
## 9 4.92 227 2 ozone
## 10 4.96 258 2 ozone
## 11 3.98 152 3 ozone
## 12 4.36 174 3 ozone
## 13 4.79 201 3 ozone
## 14 4.99 227 3 ozone
## 15 5.03 258 3 ozone
## 16 4.36 152 4 ozone
## 17 4.77 174 4 ozone
## 18 5.10 201 4 ozone
## 19 5.30 227 4 ozone
## 20 5.36 258 4 ozone
## 21 4.34 152 5 ozone
## 22 4.95 174 5 ozone
## 23 5.42 201 5 ozone
## 24 5.97 227 5 ozone
## 25 6.28 258 5 ozone
## 26 4.59 152 6 ozone
## 27 5.08 174 6 ozone
## 28 5.36 201 6 ozone
## 29 5.76 227 6 ozone
## 30 6.00 258 6 ozone
## 31 4.41 152 7 ozone
## 32 4.56 174 7 ozone
## 33 4.95 201 7 ozone
## 34 5.23 227 7 ozone
## 35 5.33 258 7 ozone
## 36 4.24 152 8 ozone
## 37 4.64 174 8 ozone
## 38 4.95 201 8 ozone
## 39 5.38 227 8 ozone
## 40 5.48 258 8 ozone
## 41 4.82 152 9 ozone
## 42 5.17 174 9 ozone
## 43 5.76 201 9 ozone
## 44 6.12 227 9 ozone
## 45 6.24 258 9 ozone
## 46 3.84 152 10 ozone
## 47 4.17 174 10 ozone
## 48 4.67 201 10 ozone
## 49 4.67 227 10 ozone
## 50 4.80 258 10 ozone
## 51 4.07 152 11 ozone
## 52 4.31 174 11 ozone
## 53 4.90 201 11 ozone
## 54 5.10 227 11 ozone
## 55 5.10 258 11 ozone
## 56 4.28 152 12 ozone
## 57 4.80 174 12 ozone
## 58 5.27 201 12 ozone
## 59 5.55 227 12 ozone
## 60 5.65 258 12 ozone
## 61 4.47 152 13 ozone
## 62 4.89 174 13 ozone
## 63 5.23 201 13 ozone
## 64 5.55 227 13 ozone
## 65 5.74 258 13 ozone
## 66 4.46 152 14 ozone
## 67 4.84 174 14 ozone
## 68 5.11 201 14 ozone
## 69 5.34 227 14 ozone
## 70 5.46 258 14 ozone
## 71 4.60 152 15 ozone
## 72 4.08 174 15 ozone
## 73 4.17 201 15 ozone
## 74 4.35 227 15 ozone
## 75 4.59 258 15 ozone
## 76 3.73 152 16 ozone
## 77 4.15 174 16 ozone
## 78 4.61 201 16 ozone
## 79 4.87 227 16 ozone
## 80 4.93 258 16 ozone
## 81 4.67 152 17 ozone
## 82 4.88 174 17 ozone
## 83 5.18 201 17 ozone
## 84 5.34 227 17 ozone
## 85 5.49 258 17 ozone
## 86 2.96 152 18 ozone
## 87 3.47 174 18 ozone
## 88 3.76 201 18 ozone
## 89 3.89 227 18 ozone
## 90 4.30 258 18 ozone
## 91 3.24 152 19 ozone
## 92 3.93 174 19 ozone
## 93 4.76 201 19 ozone
## 94 4.62 227 19 ozone
## 95 4.64 258 19 ozone
## 96 4.36 152 20 ozone
## 97 4.77 174 20 ozone
## 98 5.02 201 20 ozone
## 99 5.26 227 20 ozone
## 100 5.45 258 20 ozone
## 101 4.04 152 21 ozone
## 102 4.64 174 21 ozone
## 103 4.86 201 21 ozone
## 104 5.09 227 21 ozone
## 105 5.25 258 21 ozone
## 106 3.53 152 22 ozone
## 107 4.25 174 22 ozone
## 108 4.68 201 22 ozone
## 109 4.97 227 22 ozone
## 110 5.18 258 22 ozone
## 111 4.22 152 23 ozone
## 112 4.69 174 23 ozone
## 113 5.07 201 23 ozone
## 114 5.37 227 23 ozone
## 115 5.58 258 23 ozone
## 116 2.79 152 24 ozone
## 117 3.10 174 24 ozone
## 118 3.30 201 24 ozone
## 119 3.38 227 24 ozone
## 120 3.55 258 24 ozone
## 121 3.30 152 25 ozone
## 122 3.90 174 25 ozone
## 123 4.34 201 25 ozone
## 124 4.96 227 25 ozone
## 125 5.40 258 25 ozone
## 126 3.34 152 26 ozone
## 127 3.81 174 26 ozone
## 128 4.21 201 26 ozone
## 129 4.54 227 26 ozone
## 130 4.86 258 26 ozone
## 131 3.76 152 27 ozone
## 132 4.36 174 27 ozone
## 133 4.70 201 27 ozone
## 134 5.44 227 27 ozone
## 135 5.32 258 27 ozone
## 136 4.49 152 28 ozone
## 137 4.76 174 28 ozone
## 138 5.15 201 28 ozone
## 139 5.37 227 28 ozone
## 140 5.56 258 28 ozone
## 141 4.88 152 29 ozone
## 142 5.14 174 29 ozone
## 143 5.52 201 29 ozone
## 144 6.08 227 29 ozone
## 145 6.17 258 29 ozone
## 146 4.88 152 30 ozone
## 147 5.32 174 30 ozone
## 148 5.63 201 30 ozone
## 149 5.75 227 30 ozone
## 150 5.94 258 30 ozone
## 151 3.80 152 31 ozone
## 152 4.16 174 31 ozone
## 153 4.45 201 31 ozone
## 154 4.89 227 31 ozone
## 155 5.05 258 31 ozone
## 156 4.46 152 32 ozone
## 157 4.62 174 32 ozone
## 158 5.00 201 32 ozone
## 159 5.40 227 32 ozone
## 160 5.49 258 32 ozone
## 161 4.29 152 33 ozone
## 162 4.82 174 33 ozone
## 163 5.32 201 33 ozone
## 164 5.46 227 33 ozone
## 165 5.50 258 33 ozone
## 166 4.06 152 34 ozone
## 167 4.58 174 34 ozone
## 168 4.81 201 34 ozone
## 169 5.12 227 34 ozone
## 170 5.27 258 34 ozone
## 171 5.16 152 35 ozone
## 172 5.43 174 35 ozone
## 173 5.71 201 35 ozone
## 174 6.08 227 35 ozone
## 175 6.21 258 35 ozone
## 176 3.81 152 36 ozone
## 177 4.12 174 36 ozone
## 178 4.42 201 36 ozone
## 179 4.62 227 36 ozone
## 180 4.60 258 36 ozone
## 181 5.09 152 37 ozone
## 182 5.62 174 37 ozone
## 183 5.90 201 37 ozone
## 184 6.36 227 37 ozone
## 185 6.49 258 37 ozone
## 186 4.13 152 38 ozone
## 187 4.71 174 38 ozone
## 188 5.27 201 38 ozone
## 189 5.56 227 38 ozone
## 190 5.72 258 38 ozone
## 191 4.85 152 39 ozone
## 192 5.36 174 39 ozone
## 193 5.52 201 39 ozone
## 194 5.96 227 39 ozone
## 195 6.13 258 39 ozone
## 196 4.11 152 40 ozone
## 197 4.62 174 40 ozone
## 198 4.95 201 40 ozone
## 199 5.28 227 40 ozone
## 200 5.43 258 40 ozone
## 201 4.95 152 41 ozone
## 202 5.39 174 41 ozone
## 203 5.82 201 41 ozone
## 204 6.42 227 41 ozone
## 205 6.48 258 41 ozone
## 206 4.36 152 42 ozone
## 207 4.65 174 42 ozone
## 208 5.04 201 42 ozone
## 209 5.38 227 42 ozone
## 210 5.47 258 42 ozone
## 211 4.05 152 43 ozone
## 212 4.65 174 43 ozone
## 213 5.09 201 43 ozone
## 214 5.44 227 43 ozone
## 215 5.60 258 43 ozone
## 216 3.76 152 44 ozone
## 217 4.27 174 44 ozone
## 218 4.59 201 44 ozone
## 219 5.10 227 44 ozone
## 220 5.25 258 44 ozone
## 221 2.84 152 45 ozone
## 222 3.25 174 45 ozone
## 223 3.69 201 45 ozone
## 224 4.16 227 45 ozone
## 225 4.21 258 45 ozone
## 226 4.33 152 46 ozone
## 227 4.80 174 46 ozone
## 228 5.09 201 46 ozone
## 229 5.42 227 46 ozone
## 230 5.61 258 46 ozone
## 231 3.99 152 47 ozone
## 232 4.55 174 47 ozone
## 233 4.91 201 47 ozone
## 234 5.26 227 47 ozone
## 235 5.30 258 47 ozone
## 236 3.50 152 48 ozone
## 237 3.75 174 48 ozone
## 238 3.97 201 48 ozone
## 239 4.71 227 48 ozone
## 240 4.85 258 48 ozone
## 241 3.31 152 49 ozone
## 242 3.45 174 49 ozone
## 243 4.16 201 49 ozone
## 244 4.48 227 49 ozone
## 245 4.54 258 49 ozone
## 246 3.03 152 50 ozone
## 247 3.55 174 50 ozone
## 248 3.97 201 50 ozone
## 249 4.40 227 50 ozone
## 250 4.58 258 50 ozone
## 251 3.27 152 51 ozone
## 252 3.83 174 51 ozone
## 253 4.44 201 51 ozone
## 254 4.80 227 51 ozone
## 255 4.89 258 51 ozone
## 256 3.56 152 52 ozone
## 257 4.18 174 52 ozone
## 258 4.70 201 52 ozone
## 259 5.27 227 52 ozone
## 260 5.28 258 52 ozone
## 261 3.39 152 53 ozone
## 262 3.73 174 53 ozone
## 263 3.92 201 53 ozone
## 264 4.11 227 53 ozone
## 265 4.15 258 53 ozone
## 266 3.72 152 54 ozone
## 267 4.16 174 54 ozone
## 268 4.55 201 54 ozone
## 269 5.03 227 54 ozone
## 270 5.02 258 54 ozone
## 271 4.53 152 55 control
## 272 5.05 174 55 control
## 273 5.18 201 55 control
## 274 5.41 227 55 control
## 275 5.42 258 55 control
## 276 4.97 152 56 control
## 277 5.32 174 56 control
## 278 5.83 201 56 control
## 279 6.29 227 56 control
## 280 6.45 258 56 control
## 281 4.37 152 57 control
## 282 4.81 174 57 control
## 283 5.03 201 57 control
## 284 5.19 227 57 control
## 285 5.40 258 57 control
## 286 4.58 152 58 control
## 287 4.99 174 58 control
## 288 5.37 201 58 control
## 289 5.68 227 58 control
## 290 5.93 258 58 control
## 291 4.00 152 59 control
## 292 4.50 174 59 control
## 293 4.92 201 59 control
## 294 5.44 227 59 control
## 295 5.87 258 59 control
## 296 4.73 152 60 control
## 297 5.05 174 60 control
## 298 5.33 201 60 control
## 299 5.92 227 60 control
## 300 6.01 258 60 control
## 301 5.15 152 61 control
## 302 5.63 174 61 control
## 303 6.11 201 61 control
## 304 6.39 227 61 control
## 305 6.61 258 61 control
## 306 4.10 152 62 control
## 307 4.46 174 62 control
## 308 4.84 201 62 control
## 309 5.29 227 62 control
## 310 5.48 258 62 control
## 311 3.22 152 63 control
## 312 3.85 174 63 control
## 313 4.47 201 63 control
## 314 4.85 227 63 control
## 315 5.11 258 63 control
## 316 2.23 152 64 control
## 317 2.89 174 64 control
## 318 3.16 201 64 control
## 319 3.40 227 64 control
## 320 3.52 258 64 control
## 321 3.65 152 65 control
## 322 4.36 174 65 control
## 323 4.76 201 65 control
## 324 5.18 227 65 control
## 325 5.44 258 65 control
## 326 3.40 152 66 control
## 327 3.92 174 66 control
## 328 4.50 201 66 control
## 329 4.97 227 66 control
## 330 5.14 258 66 control
## 331 5.16 152 67 control
## 332 5.49 174 67 control
## 333 5.74 201 67 control
## 334 6.05 227 67 control
## 335 6.21 258 67 control
## 336 4.04 152 68 control
## 337 4.52 174 68 control
## 338 5.15 201 68 control
## 339 5.59 227 68 control
## 340 5.87 258 68 control
## 341 4.52 152 69 control
## 342 4.91 174 69 control
## 343 5.04 201 69 control
## 344 5.71 227 69 control
## 345 5.97 258 69 control
## 346 4.56 152 70 control
## 347 5.12 174 70 control
## 348 5.40 201 70 control
## 349 5.69 227 70 control
## 350 5.89 258 70 control
## 351 4.90 152 71 control
## 352 5.35 174 71 control
## 353 5.71 201 71 control
## 354 6.12 227 71 control
## 355 6.25 258 71 control
## 356 4.83 152 72 control
## 357 5.10 174 72 control
## 358 5.43 201 72 control
## 359 5.59 227 72 control
## 360 6.04 258 72 control
## 361 5.46 152 73 control
## 362 5.79 174 73 control
## 363 6.12 201 73 control
## 364 6.41 227 73 control
## 365 6.63 258 73 control
## 366 4.17 152 74 control
## 367 4.67 174 74 control
## 368 5.16 201 74 control
## 369 5.56 227 74 control
## 370 5.75 258 74 control
## 371 3.35 152 75 control
## 372 4.05 174 75 control
## 373 4.51 201 75 control
## 374 5.22 227 75 control
## 375 5.44 258 75 control
## 376 3.33 152 76 control
## 377 3.82 174 76 control
## 378 4.38 201 76 control
## 379 4.99 227 76 control
## 380 5.17 258 76 control
## 381 3.41 152 77 control
## 382 3.68 174 77 control
## 383 4.03 201 77 control
## 384 4.28 227 77 control
## 385 4.54 258 77 control
## 386 4.50 152 78 control
## 387 4.80 174 78 control
## 388 5.28 201 78 control
## 389 5.83 227 78 control
## 390 6.16 258 78 control
## 391 2.99 152 79 control
## 392 3.61 174 79 control
## 393 4.48 201 79 control
## 394 4.91 227 79 control
## 395 5.06 258 79 control