Calculate percentage given condition

Question

I am new to this website and to coding as well. I was wondering if any of you could help me out

I need to calculate the Top 5 Movies, by rating distribution, calculating the percentage of ratings for each movie that are 4 stars or higher.

So far I was only able to calculate the number of occurrences using dplyr.

Is it possible to calculate it using dplyr (something similar to my coding)?

I'm not sure whether I need to mutate to come up with the solution or if there's another way to do so.

My code so far:

dfAux1 <- na.omit(dfAux)
dfAux1 %>%
  group_by(movie) %>%
  summarise(tot = n()) %>%
  arrange(desc(tot))%>%
  head(5)

the result should be something like this:

**Expected result**:
0.7000000, 'The Shawshank Redemption'
0.5333333, 'Star Wars IV - A New Hope'
0.5000000, 'Gladiator'
0.4444444, 'Blade Runner'
0.4375000, 'The Silence of the Lambs'

and so far this is my result:

# A tibble: 5 x 2
                              movie   tot
                             <fctr> <int>
1                         Toy Story    17
2          The Silence of the Lambs    16
3         Star Wars IV - A New Hope    15
4 Star Wars VI - Return of the Jedi    14
5                  Independence Day    13

edit:

str(dfAux1)
'data.frame':   241 obs. of  2 variables:
 $ Rating: int  1 5 4 2 4 5 4 2 3 2 ...
 $ movie : Factor w/ 20 levels "Star Wars IV - A New Hope",..: 1 1 1 1 1 1 1 1 1 1 ...
 - attr(*, "na.action")=Class 'omit'  Named int [1:159] 3 4 7 16 17 23 27 28 34 36 ...
  .. ..- attr(*, "names")= chr [1:159] "3" "4" "7" "16" ...

dput(dfAux1)
structure(list(Rating = c(1L, 5L, 4L, 2L, 4L, 5L, 4L, 2L, 3L, 
2L, 3L, 4L, 4L, 5L, 1L, 5L, 3L, 3L, 3L, 4L, 1L, 2L, 1L, 5L, 3L, 
4L, 5L, 1L, 2L, 2L, 4L, 4L, 3L, 5L, 2L, 3L, 1L, 1L, 2L, 2L, 5L, 
1L, 4L, 1L, 4L, 5L, 5L, 5L, 4L, 4L, 4L, 2L, 4L, 1L, 3L, 2L, 3L, 
2L, 4L, 2L, 5L, 3L, 4L, 1L, 5L, 4L, 2L, 1L, 1L, 4L, 2L, 4L, 5L, 
5L, 2L, 1L, 4L, 2L, 1L, 4L, 2L, 3L, 2L, 4L, 4L, 5L, 2L, 4L, 3L, 
2L, 2L, 4L, 2L, 2L, 2L, 3L, 4L, 1L, 5L, 4L, 3L, 5L, 2L, 1L, 3L, 
4L, 4L, 2L, 3L, 4L, 1L, 3L, 2L, 5L, 3L, 2L, 3L, 4L, 1L, 1L, 4L, 
1L, 4L, 5L, 1L, 3L, 2L, 2L, 3L, 5L, 5L, 1L, 2L, 3L, 5L, 2L, 3L, 
1L, 2L, 1L, 4L, 1L, 2L, 2L, 3L, 3L, 2L, 1L, 1L, 1L, 5L, 2L, 4L, 
1L, 4L, 3L, 1L, 2L, 2L, 3L, 4L, 2L, 3L, 2L, 4L, 3L, 4L, 3L, 2L, 
2L, 4L, 5L, 2L, 1L, 5L, 1L, 4L, 5L, 2L, 3L, 3L, 2L, 5L, 5L, 4L, 
1L, 3L, 1L, 2L, 1L, 5L, 5L, 2L, 4L, 2L, 4L, 2L, 5L, 2L, 5L, 5L, 
1L, 5L, 1L, 3L, 2L, 2L, 3L, 5L, 1L, 3L, 1L, 5L, 3L, 3L, 1L, 2L, 
4L, 1L, 5L, 3L, 1L, 1L, 5L, 5L, 1L, 5L, 3L, 3L, 2L, 3L, 3L, 2L, 
2L, 2L, 5L, 4L, 2L, 1L, 4L, 5L), movie = structure(c(1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 5L, 
5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 6L, 
6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 7L, 7L, 7L, 7L, 7L, 
7L, 7L, 7L, 7L, 7L, 7L, 7L, 7L, 7L, 7L, 7L, 7L, 8L, 8L, 8L, 8L, 
8L, 8L, 8L, 8L, 8L, 8L, 8L, 9L, 9L, 9L, 9L, 9L, 9L, 9L, 9L, 9L, 
9L, 9L, 10L, 10L, 10L, 10L, 10L, 10L, 10L, 10L, 10L, 10L, 10L, 
11L, 11L, 11L, 11L, 11L, 11L, 11L, 11L, 11L, 11L, 11L, 12L, 12L, 
12L, 12L, 12L, 12L, 12L, 12L, 12L, 12L, 12L, 12L, 13L, 13L, 13L, 
13L, 13L, 13L, 13L, 13L, 13L, 13L, 13L, 13L, 13L, 14L, 14L, 14L, 
14L, 14L, 14L, 14L, 14L, 14L, 15L, 15L, 15L, 15L, 15L, 15L, 15L, 
15L, 15L, 15L, 15L, 15L, 16L, 16L, 16L, 16L, 16L, 16L, 16L, 16L, 
16L, 16L, 16L, 16L, 17L, 17L, 17L, 17L, 17L, 17L, 17L, 17L, 17L, 
17L, 17L, 17L, 18L, 18L, 18L, 18L, 18L, 18L, 18L, 18L, 18L, 18L, 
18L, 18L, 19L, 19L, 19L, 19L, 19L, 19L, 19L, 19L, 19L, 19L, 19L, 
20L, 20L, 20L, 20L, 20L, 20L, 20L, 20L, 20L, 20L), .Label = c("Star Wars IV - A New Hope", 
"Star Wars VI - Return of the Jedi", "Forrest Gump", "The Shawshank Redemption", 
"The Silence of the Lambs", "Gladiator", "Toy Story", "Saving Private Ryan", 
"Pulp Fiction", "Stand by Me", "Shakespeare in Love", "Total Recall", 
"Independence Day", "Blade Runner", "Groundhog Day", "The Matrix", 
"Schindler's List", "The Sixth Sense", "Raiders of the Lost Ark", 
"Babe"), class = "factor")), .Names = c("Rating", "movie"), row.names = c(1L, 
2L, 5L, 6L, 8L, 9L, 10L, 11L, 12L, 13L, 14L, 15L, 18L, 19L, 20L, 
21L, 22L, 24L, 25L, 26L, 29L, 30L, 31L, 32L, 33L, 35L, 38L, 39L, 
40L, 41L, 45L, 46L, 47L, 51L, 52L, 54L, 56L, 58L, 60L, 62L, 63L, 
65L, 66L, 67L, 69L, 70L, 73L, 78L, 80L, 81L, 82L, 83L, 85L, 87L, 
88L, 89L, 90L, 92L, 93L, 94L, 95L, 96L, 97L, 98L, 100L, 101L, 
102L, 104L, 105L, 107L, 108L, 109L, 111L, 115L, 116L, 118L, 119L, 
121L, 122L, 123L, 124L, 126L, 128L, 129L, 130L, 131L, 132L, 133L, 
134L, 135L, 137L, 138L, 139L, 140L, 141L, 144L, 145L, 146L, 147L, 
149L, 150L, 153L, 156L, 159L, 160L, 164L, 166L, 167L, 168L, 170L, 
172L, 175L, 177L, 178L, 179L, 180L, 181L, 182L, 183L, 185L, 186L, 
189L, 194L, 195L, 196L, 199L, 200L, 201L, 202L, 205L, 206L, 207L, 
209L, 212L, 216L, 217L, 219L, 220L, 222L, 223L, 224L, 225L, 226L, 
228L, 229L, 231L, 233L, 234L, 235L, 239L, 241L, 242L, 243L, 244L, 
246L, 248L, 249L, 250L, 251L, 252L, 253L, 254L, 255L, 261L, 263L, 
264L, 265L, 267L, 268L, 274L, 278L, 280L, 282L, 283L, 284L, 286L, 
288L, 289L, 292L, 293L, 294L, 295L, 296L, 300L, 301L, 303L, 305L, 
307L, 310L, 311L, 312L, 314L, 316L, 317L, 319L, 320L, 321L, 322L, 
323L, 324L, 325L, 328L, 330L, 334L, 335L, 336L, 338L, 340L, 341L, 
342L, 343L, 344L, 345L, 346L, 348L, 350L, 351L, 356L, 358L, 360L, 
362L, 363L, 364L, 367L, 368L, 371L, 373L, 375L, 376L, 378L, 380L, 
383L, 384L, 386L, 387L, 389L, 391L, 392L, 395L, 396L, 398L), class = "data.frame", na.action = structure(c(3L, 
4L, 7L, 16L, 17L, 23L, 27L, 28L, 34L, 36L, 37L, 42L, 43L, 44L, 
48L, 49L, 50L, 53L, 55L, 57L, 59L, 61L, 64L, 68L, 71L, 72L, 74L, 
75L, 76L, 77L, 79L, 84L, 86L, 91L, 99L, 103L, 106L, 110L, 112L, 
113L, 114L, 117L, 120L, 125L, 127L, 136L, 142L, 143L, 148L, 151L, 
152L, 154L, 155L, 157L, 158L, 161L, 162L, 163L, 165L, 169L, 171L, 
173L, 174L, 176L, 184L, 187L, 188L, 190L, 191L, 192L, 193L, 197L, 
198L, 203L, 204L, 208L, 210L, 211L, 213L, 214L, 215L, 218L, 221L, 
227L, 230L, 232L, 236L, 237L, 238L, 240L, 245L, 247L, 256L, 257L, 
258L, 259L, 260L, 262L, 266L, 269L, 270L, 271L, 272L, 273L, 275L, 
276L, 277L, 279L, 281L, 285L, 287L, 290L, 291L, 297L, 298L, 299L, 
302L, 304L, 306L, 308L, 309L, 313L, 315L, 318L, 326L, 327L, 329L, 
331L, 332L, 333L, 337L, 339L, 347L, 349L, 352L, 353L, 354L, 355L, 
357L, 359L, 361L, 365L, 366L, 369L, 370L, 372L, 374L, 377L, 379L, 
381L, 382L, 385L, 388L, 390L, 393L, 394L, 397L, 399L, 400L), .Names = c("3", 
"4", "7", "16", "17", "23", "27", "28", "34", "36", "37", "42", 
"43", "44", "48", "49", "50", "53", "55", "57", "59", "61", "64", 
"68", "71", "72", "74", "75", "76", "77", "79", "84", "86", "91", 
"99", "103", "106", "110", "112", "113", "114", "117", "120", 
"125", "127", "136", "142", "143", "148", "151", "152", "154", 
"155", "157", "158", "161", "162", "163", "165", "169", "171", 
"173", "174", "176", "184", "187", "188", "190", "191", "192", 
"193", "197", "198", "203", "204", "208", "210", "211", "213", 
"214", "215", "218", "221", "227", "230", "232", "236", "237", 
"238", "240", "245", "247", "256", "257", "258", "259", "260", 
"262", "266", "269", "270", "271", "272", "273", "275", "276", 
"277", "279", "281", "285", "287", "290", "291", "297", "298", 
"299", "302", "304", "306", "308", "309", "313", "315", "318", 
"326", "327", "329", "331", "332", "333", "337", "339", "347", 
"349", "352", "353", "354", "355", "357", "359", "361", "365", 
"366", "369", "370", "372", "374", "377", "379", "381", "382", 
"385", "388", "390", "393", "394", "397", "399", "400"), class = "omit"))

Answer 1

I am using data.table instead of dplyr

library(data.table)
setDT(dfAux1)  # make dfAux1 as data table by reference

# calculate total number by movies, then compute percent for `Rating >= 4` by movies and then sort `tot` by descending order and also eliminating duplicates in movies using `.SD[1]` which gives the first row in each movie. 
dfAux1[, .(Rating, tot = .N), by = movie ][Rating >= 4, .(percent = .N/tot, tot), by = movie ][order(-tot), .SD[1], by = movie]

#                                movie    percent tot
# 1:                         Toy Story 0.35294118  17
# 2:          The Silence of the Lambs 0.43750000  16
# 3:         Star Wars IV - A New Hope 0.53333333  15
# 4: Star Wars VI - Return of the Jedi 0.35714286  14
# 5:                  Independence Day 0.30769231  13
# 6:                         Gladiator 0.50000000  12
# 7:                      Total Recall 0.08333333  12
# 8:                     Groundhog Day 0.41666667  12
# 9:                        The Matrix 0.41666667  12
# 10:                  Schindler's List 0.33333333  12
# 11:                   The Sixth Sense 0.33333333  12
# 12:               Saving Private Ryan 0.36363636  11
# 13:                      Pulp Fiction 0.36363636  11
# 14:                       Stand by Me 0.36363636  11
# 15:               Shakespeare in Love 0.27272727  11
# 16:           Raiders of the Lost Ark 0.27272727  11
# 17:                      Forrest Gump 0.30000000  10
# 18:          The Shawshank Redemption 0.70000000  10
# 19:                              Babe 0.40000000  10
# 20:                      Blade Runner 0.44444444   9