尝试使用 rvest html_table 解析 html 表时出错

Question

我正在尝试从此网址读取表格：

https://www.nseindia.com/live_market/dynaContent/live_analysis/most_active_underlyings.htm

library(rvest)
library(magrittr)

url = "https://www.nseindia.com/live_market/dynaContent/live_analysis/most_active_underlyings.htm"
tbl = read_html(url) %>% html_node("table") %>% html_table()

错误信息：

Error in matrix(NA_character_, nrow = n, ncol = maxp) : 
  invalid 'ncol' value (too large or NA)
In addition: Warning messages:
1: In max(p) : no non-missing arguments to max; returning -Inf
2: In matrix(NA_character_, nrow = n, ncol = maxp) :
  NAs introduced by coercion to integer range

Answer 1

看起来基础数据可通过this URL 的 GET 请求获得

要将其放入 R... 使用此

library(jsonlite)
tmp <- fromJSON("https://www.nseindia.com/live_market/dynaContent/live_analysis/underlyings/ActiveUnderlyingsValue.json")
df <- tmp$data

> head(df)
  FO_SYMBOL  VOLUME1   VOLUME2 TOTAL_VOLUME   VALUE1      VALUE2 TOTAL_VALUE UNDERLYINGVALUE
1 BANKNIFTY 1,36,046 83,23,989    84,60,035 8,521.68 5,23,514.39 5,32,036.07       31,160.35
2     NIFTY 1,01,176 41,10,138    42,11,314 9,050.23 3,69,056.93 3,78,107.16       11,856.80
3      SBIN   49,403    75,206     1,24,609 4,722.48    7,455.53   12,178.01          313.20
4  RELIANCE   15,093    30,744       45,837 1,183.71    2,459.68    3,643.39        1,564.90
5       TCS   20,578    40,737       61,315 1,044.29    2,139.57    3,183.86        2,016.25
6 ICICIBANK   21,264    19,857       41,121 1,548.93    1,462.62    3,011.55          529.75
        OP OPENINTEREST
1 1,824.84     7,75,725
2 1,349.93    15,54,357
3   143.40       69,024
4    27.77     1,29,759
5    26.17     1,00,669
6    23.59       99,142