这是我问题的后续这里。
我想学习如何循环遍历列表，然后将结果存储（或绑定）在一起。
目标是首先创建游戏 id 列表，将它们附加到通用 url，然后循环这些以获取 boxscore 表，最后将结果存储（或将它们添加到一起）在数据框中。
我像这样定义了 game_ids：
game_ids <- list(401559239,401559240)
和网址：
url_ = "https://www.espn.com/nhl/boxscore/_/gameId"
然后我将此循环代码添加到建议解决方案的开头：
for (game_id in game_ids) {
url2 = paste(url_, game_id, sep = '/')
完整代码：
library(rvest)
library(dplyr)
library(purrr)
library(tidyr)
game_ids <- list(401559239,401559240)
url_ = "https://www.espn.com/nhl/boxscore/_/gameId"
for (game_id in game_ids) {
url2 = paste(url_, game_id, sep = '/')
boxscore <- read_html(url2) %>%
# extract team sections (2)
html_elements("div.Boxscore div.Wrapper") %>%
# extract team names, use as list element names
set_names(html_elements(., ".BoxscoreItem__TeamName") %>% html_text()) %>%
# extact table elements, 4 per team
map(\(team_section) html_elements(team_section, "table")) %>%
map(\(team_tables) list(
# bind tables 1 & 2 (skaters/defensemen and data section)
tbl_1 = html_table(team_tables[1:2]) %>%
bind_cols(.name_repair = "minimal") %>%
# column names from the first row
set_names(.[1,]) %>%
rename(player = Skaters) %>%
# position to spearate column
mutate(position = if_else(G == "G", player, NA), .before = 1) %>%
fill(position, .direction = "down") %>%
# remove rows with header info
filter(G != "G"),
# bind tables 3 & 4 (goalies and data section)
tbl_2 = html_table(team_tables[3:4]) %>%
bind_cols(.name_repair = "minimal") %>%
set_names(.[1,]) %>%
filter(SA != "SA")
)
)
output = boxscore %>%
map("tbl_1") %>%
list_rbind(names_to = "team")
}
我将其添加到循环的末尾（在
list_rbindprint(res)
我可以看到两场比赛的结果：
[1] "https://www.espn.com/nhl/boxscore/_/gameId/401559239"
# A tibble: 36 × 22
team position player G A `+/-` S SM BS PN PIM HT TK GV SHFT TOI PPTOI SHTOI
<chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr>
1 Mont… Skaters J. An… 0 0 -1 3 1 1 1 2 2 0 1 25 17:31 1:46 0:00
2 Mont… Skaters C. Ca… 1 0 0 1 1 1 0 0 2 0 1 23 19:11 3:59 0:00
3 Mont… Skaters K. Da… 0 2 2 3 0 0 0 0 3 1 0 23 21:22 3:59 0:15
4 Mont… Skaters J. Ev… 1 0 1 1 0 0 1 2 3 2 0 19 11:22 0:12 2:27
5 Mont… Skaters B. Ga… 0 0 0 0 0 1 0 0 1 0 0 17 12:34 1:50 0:00
6 Mont… Skaters R. Ha… 0 1 0 0 1 2 0 0 3 0 1 18 13:39 0:11 2:56
7 Mont… Skaters S. Mo… 0 0 -1 3 2 1 0 0 0 1 0 22 18:51 4:00 1:10
8 Mont… Skaters A. Ne… 2 0 1 2 0 0 1 2 2 0 2 22 16:46 1:49 0:00
9 Mont… Skaters T. Pe… 0 0 0 0 1 0 0 0 4 0 0 18 12:10 0:00 1:10
10 Mont… Skaters J. Sl… 0 1 2 1 3 0 0 0 3 2 1 20 15:25 1:28 0:00
# ℹ 26 more rows
# ℹ 4 more variables: ESTOI <chr>, FW <chr>, FL <chr>, `FO%` <chr>
# ℹ Use `print(n = ...)` to see more rows
[1] "https://www.espn.com/nhl/boxscore/_/gameId/401559240"
# A tibble: 35 × 22
team position player G A `+/-` S SM BS PN PIM HT TK GV SHFT TOI PPTOI SHTOI
<chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr>
1 Otta… Skaters D. Ba… 0 0 -1 5 3 0 0 0 1 0 0 24 18:21 4:44 0:18
2 Otta… Skaters R. Ch… 0 0 1 3 0 0 0 0 4 0 0 24 13:28 0:07 2:51
3 Otta… Skaters C. Gi… 0 0 -1 1 1 1 1 2 1 0 1 29 19:48 4:19 1:45
4 Otta… Skaters R. Gr… 0 0 -1 2 0 0 0 0 0 0 0 26 16:04 3:49 3:15
5 Otta… Skaters M. Jo… 1 1 1 1 2 2 0 0 0 1 0 29 17:52 0:21 6:00
6 Otta… Skaters M. Ka… 0 0 -1 0 0 1 1 2 0 0 0 15 7:33 0:00 0:33
7 Otta… Skaters P. Ke… 1 1 0 2 1 0 0 0 0 0 0 25 12:40 0:14 4:42
8 Otta… Skaters D. Ku… 0 0 0 3 0 0 0 0 0 0 1 21 14:32 2:58 0:00
9 Otta… Skaters T. St… 1 0 -1 3 0 0 2 4 1 0 2 28 21:44 5:25 2:12
10 Otta… Skaters V. Ta… 0 0 0 0 1 0 0 0 1 0 0 23 13:12 3:00 0:00
# ℹ 25 more rows
# ℹ 4 more variables: ESTOI <chr>, FW <chr>, FL <chr>, `FO%` <chr>
# ℹ Use `print(n = ...)` to see more rows
但是我不知道如何将它们在数据框中绑定在一起。
我尝试了
res = rbind(output)res = do.call(rbind,output)但是两者都只返回最后一场比赛的结果：
> head(res,10)
# A tibble: 10 × 22
team position player G A `+/-` S SM BS PN PIM HT TK GV SHFT TOI PPTOI SHTOI
<chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr> <chr>
1 Otta… Skaters D. Ba… 0 0 -1 5 3 0 0 0 1 0 0 24 18:21 4:44 0:18
2 Otta… Skaters R. Ch… 0 0 1 3 0 0 0 0 4 0 0 24 13:28 0:07 2:51
3 Otta… Skaters C. Gi… 0 0 -1 1 1 1 1 2 1 0 1 29 19:48 4:19 1:45
4 Otta… Skaters R. Gr… 0 0 -1 2 0 0 0 0 0 0 0 26 16:04 3:49 3:15
5 Otta… Skaters M. Jo… 1 1 1 1 2 2 0 0 0 1 0 29 17:52 0:21 6:00
6 Otta… Skaters M. Ka… 0 0 -1 0 0 1 1 2 0 0 0 15 7:33 0:00 0:33
7 Otta… Skaters P. Ke… 1 1 0 2 1 0 0 0 0 0 0 25 12:40 0:14 4:42
8 Otta… Skaters D. Ku… 0 0 0 3 0 0 0 0 0 0 1 21 14:32 2:58 0:00
9 Otta… Skaters T. St… 1 0 -1 3 0 0 2 4 1 0 2 28 21:44 5:25 2:12
10 Otta… Skaters V. Ta… 0 0 0 0 1 0 0 0 1 0 0 23 13:12 3:00 0:00
# ℹ 4 more variables: ESTOI <chr>, FW <chr>, FL <chr>, `FO%` <chr>
如何存储每个游戏所需的输出，并添加到数据框？
使用所有代码很难发现问题。 :) 然而，解决方案很简单：
在每次迭代中，您都会覆盖输出变量。因此，最终您只能看到上一次迭代的游戏。要解决此问题，您可以在循环之前将输出创建为空列表，并在每次迭代时填充它。然后，您可以绑定行。类似的东西应该有效：
output <- list()
for (game_id in game_ids) {
print(game_id)
url2 = paste(url_, game_id, sep = '/')
boxscore <- read_html(url2) %>%
# extract team sections (2)
html_elements("div.Boxscore div.Wrapper") %>%
# extract team names, use as list element names
set_names(html_elements(., ".BoxscoreItem__TeamName") %>% html_text()) %>%
# extact table elements, 4 per team
map(\(team_section) html_elements(team_section, "table")) %>%
map(
\(team_tables) list(
# bind tables 1 & 2 (skaters/defensemen and data section)
tbl_1 = html_table(team_tables[1:2]) %>%
bind_cols(.name_repair = "minimal") %>%
# column names from the first row
set_names(.[1, ]) %>%
dplyr::rename(player = Skaters) %>%
# position to spearate column
mutate(
position = if_else(G == "G", player, NA),
.before = 1
) %>%
fill(position, .direction = "down") %>%
# remove rows with header info
filter(G != "G"),
# bind tables 3 & 4 (goalies and data section)
tbl_2 = html_table(team_tables[3:4]) %>%
bind_cols(.name_repair = "minimal") %>%
set_names(.[1, ]) %>%
filter(SA != "SA")
)
)
output[[as.character(game_id)]] <- boxscore %>%
map("tbl_1") %>%
list_rbind(names_to = "team")
}
output <- output |> bind_rows(.id = "game")