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在R中按组计算字符串模式数量

rgroup-bydplyr
3
我正在使用R语言尝试在数据框中获取特定字符串的分组计数，但目前尚未找到解决方案。以下是一些示例数据和我尝试使用的代码，以便您了解我的目标，更多解释请见下文：
simpson <- structure(list(season = c(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, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 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, 5L, 5L, 5L), episode_title = c("Simpsons Roasting on an Open Fire", 
"Bart the Genius", "Homer's Odyssey", "There's No Disgrace Like Home", 
"Bart the General", "Moaning Lisa", "The Call of the Simpsons", 
"The Telltale Head", "Life on the Fast Lane", "Homer's Night Out", 
"The Crepes of Wrath", "Krusty Gets Busted", "Some Enchanted Evening", 
"Bart Gets an \"F\"", "Simpson and Delilah", "Treehouse of Horror", 
"Two Cars in Every Garage and Three Eyes on Every Fish", "Dancin' Homer", 
"Dead Putting Society", "Bart vs. Thanksgiving", "Bart the Daredevil", 
"Itchy & Scratchy & Marge", "Bart Gets Hit by a Car", "One Fish, Two Fish, Blowfish, Blue Fish", 
"The Way We Was", "Homer vs. Lisa and the 8th Commandment", "Principal Charming", 
"Oh Brother, Where Art Thou?", "Bart's Dog Gets an \"F\"", "Old Money", 
"Brush with Greatness", "Lisa's Substitute", "The War of the Simpsons", 
"Three Men and a Comic Book", "Blood Feud", "Stark Raving Dad", 
"Mr. Lisa Goes to Washington", "When Flanders Failed", "Bart the Murderer", 
"Homer Defined", "Like Father, Like Clown", "Treehouse of Horror II", 
"Lisa's Pony", "Saturdays of Thunder", "Flaming Moe's", "Burns Verkaufen der Kraftwerk", 
"I Married Marge", "Radio Bart", "Lisa the Greek", "Homer Alone", 
"Bart the Lover", "Homer at the Bat", "Separate Vocations", "Dog of Death", 
"Colonel Homer", "Black Widower", "The Otto Show", "Bart's Friend Falls in Love", 
"Brother, Can You Spare Two Dimes?", "Kamp Krusty", "A Streetcar Named Marge", 
"Homer the Heretic", "Lisa the Beauty Queen", "Treehouse of Horror III", 
"Itchy & Scratchy: The Movie", "Marge Gets a Job", "New Kid on the Block", 
"Mr. Plow", "Lisa's First Word", "Homer's Triple Bypass", "Marge vs. the Monorail", 
"Selma's Choice", "Brother from the Same Planet", "I Love Lisa", 
"Duffless", "Last Exit to Springfield", "So It's Come to This: A Simpsons Clip Show", 
"The Front", "Whacking Day", "Marge in Chains", "Krusty Gets Kancelled", 
"Homer's Barbershop Quartet", "Cape Feare", "Homer Goes to College", 
"Rosebud", "Treehouse of Horror IV", "Marge on the Lam", "Bart's Inner Child", 
"Boy-Scoutz 'n the Hood", "The Last Temptation of Homer", "$pringfield (or, How I Learned to Stop Worrying and Love Legalized Gambling)", 
"Homer the Vigilante", "Bart Gets Famous", "Homer and Apu", "Lisa vs. Malibu Stacy", 
"Deep Space Homer", "Homer Loves Flanders", "Bart Gets an Elephant", 
"Burns' Heir", "Sweet Seymour Skinner's Baadasssss Song"), imdb_votes = c(3734L, 
1973L, 1709L, 1701L, 1732L, 1674L, 1638L, 1580L, 1578L, 1511L, 
1539L, 1716L, 1567L, 1638L, 1588L, 1786L, 1457L, 1381L, 1366L, 
1324L, 1522L, 1402L, 1340L, 1687L, 1392L, 1329L, 1241L, 1413L, 
1264L, 1243L, 1257L, 1684L, 1246L, 1379L, 1223L, 1798L, 1274L, 
1302L, 1446L, 1452L, 1262L, 1369L, 1243L, 1194L, 1618L, 1291L, 
1213L, 1365L, 1179L, 1176L, 1272L, 1637L, 1201L, 1165L, 1233L, 
1233L, 1176L, 1160L, 1227L, 1414L, 1339L, 1747L, 1194L, 1394L, 
1293L, 1163L, 1240L, 1595L, 1350L, 1445L, 2028L, 1153L, 1176L, 
1268L, 1209L, 1827L, 1105L, 1122L, 1234L, 1080L, 1269L, 1416L, 
2010L, 1476L, 1479L, 1437L, 1132L, 1085L, 1270L, 1308L, 1274L, 
1202L, 1123L, 1171L, 1187L, 1505L, 1191L, 1116L, 1143L, 1118L
), us_viewers_in_millions = c(26.7, 24.5, 27.5, 20.2, 27.1, 27.4, 
27.6, 28, 33.5, 30.3, 31.2, 30.4, 27.1, 33.6, 29.9, 27.4, 26.1, 
26.1, 25.4, 25.9, 26.2, 22.2, 24.8, 24.2, 26.8, 26.2, 23.9, 26.8, 
23.9, 21.2, 20.6, 17.7, 19.7, 21, 17.3, 22.9, 20.2, 22.8, 20.8, 
20.6, 20.2, 20, 23, 24.7, 23.9, 21.1, 21.9, 24.2, 23.2, 23.7, 
20.5, 24.6, 23.7, 23.4, 25.5, 17.3, 17.5, 19.5, 17.2, 21.8, 18.3, 
19.3, 19, 25.1, 20.1, 22.9, 23.1, 24, 28.6, 23.6, 23, 24.5, 23.8, 
25.2, 25.7, 22.4, 25.5, 20.1, 20, 17.3, 19.4, 19.9, 20, 18.1, 
19.5, 24, 21.7, 18.7, 20.1, 20.6, 17.9, 20.1, 20, 21.8, 20.5, 
18.2, 18, 17, 14.7, 19.7)), .Names = c("season", "episode_title", 
"imdb_votes", "us_viewers_in_millions"), row.names = c(NA, -100L
), class = c("tbl_df", "tbl", "data.frame"))

char_counts <- simpson %>%
  group_by(season) %>%
  str_count(episode_title, "Homer")

我首先按季节对数据进行了分组，然后尝试计算给定季节中任何一集标题中出现单词“Homer”的总次数。

如果您有任何建议，请不吝告知。

最好的祝福， Curtis

a) 你必须将 str_count 的结果存储在某个地方。 b) 你的列名不是 title，而是 episode_title。 - AntoniosK
感谢指出列名错误。我将那段代码从之前版本的脚本中复制过来，忘记了我已将名称从“title”更改为“episode_title”。我已编辑上述代码以反映此更改。 - Curtis
2个回答
6

要在每一行添加一个新变量，您需要使用mutate函数。除非您想按组进行汇总，否则不需要使用group_by：

simpson %>%
    mutate(homer_count = str_count(episode_title, 'Homer'))

# A tibble: 100 x 5
   season episode_title                     imdb_votes us_viewers_in_millions homer_count
    <int> <chr>                                  <int>                  <dbl>       <int>
 1      1 Simpsons Roasting on an Open Fire       3734                   26.7           0
 2      1 Bart the Genius                         1973                   24.5           0
 3      1 Homer's Odyssey                         1709                   27.5           1
 4      1 There's No Disgrace Like Home           1701                   20.2           0
 5      1 Bart the General                        1732                   27.1           0
 6      1 Moaning Lisa                            1674                   27.4           0
 7      1 The Call of the Simpsons                1638                   27.6           0
 8      1 The Telltale Head                       1580                   28             0
 9      1 Life on the Fast Lane                   1578                   33.5           0
10      1 Homer's Night Out                       1511                   30.3           1
# ... with 90 more rows

如果您想按季度计算每个Homer的使用次数，则可以使用group_by，然后使用summarize生成一个新变量，每组只有一行：

simpson %>%
    group_by(season) %>%
    summarize(homer_count = sum(str_count(episode_title, 'Homer')))

# A tibble: 5 x 2
  season homer_count
   <int>       <int>
1      1           2
2      2           2
3      3           4
4      4           2
5      5           7
2
library(dplyr)

simpson %>%
  mutate(counts = str_count(episode_title, "Homer")) %>%  # count matches for each row (vectorised function)
  group_by(season) %>%                                    # for each season
  summarise(sum_counts = sum(counts))                     # sum counts

# # A tibble: 5 x 2
#   season sum_counts
#    <int>      <int>
# 1      1          2
# 2      2          2
# 3      3          4
# 4      4          2
# 5      5          7
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