API数据获取遇连接超时：R代码报错解决方案求助

运行以下R代码获取交易所数据时，出现连接超时错误，无法建立与NASDAQ API的连接：

library(tidyquant)
library(jsonlite)
library(tidyverse)
library(readr)
library(igraph)
library(dplyr)
library(lubridate)
library(data.table)

Sp500 <- tq_index("SP500") %>% add_column(exchange = "SP500")
sp400 <- tq_index("SP400") %>% add_column(exchange = "SP400")
sp600 <- tq_index("SP600") %>% add_column(exchange = "SP600")
NASDAQ <-tq_exchange("NASDAQ") %>% add_column(exchange = "NASDAQ")
NYSE<-tq_exchange("NYSE")%>% add_column(exchange = "NYSE")
#Rus2000 <- tq_index("RUSSELL2000") %>% add_column(exchange = "RUSSELL2000")
#Rus1000 <- tq_index("RUSSELL1000") %>% add_column(exchange = "RUSSELL1000")
tickers <- rbind(NASDAQ,NYSE)

str(tickers)

报错信息：

> NASDAQ <-tq_exchange("NASDAQ") %>% add_column(exchange = "NASDAQ")
Getting data...

Error in open.connection(con, "rb") : 
  cannot open the connection to 'https://api.nasdaq.com/api/screener/stocks?tableonly=true&exchange=nasdaq&download=true'
In addition: Warning message:
In open.connection(con, "rb") :
  URL 'https://api.nasdaq.com/api/screener/stocks?tableonly=true&exchange=nasdaq&download=true': Timeout of 60 seconds was reached

• 检查网络可用性
  先在浏览器中直接访问报错里的API链接，确认网络能正常连接到该地址。如果无法访问，可能是网络限制（如防火墙、地区封锁），需要调整网络设置。

• 延长请求超时时间
  tidyquant底层依赖httr包发起请求，默认超时60秒。可以通过设置全局超时或自定义请求来延长：

  # 设置全局超时为120秒
  options(httr_timeout = 120)
  
  # 或者自定义tq_exchange的请求参数，手动添加超时
  library(httr)
  NASDAQ <- tq_exchange("NASDAQ", get = "stock.screener", 
                        options = list(timeout = timeout(120))) %>% 
    add_column(exchange = "NASDAQ")
  

• 更新tidyquant包
  旧版本的tidyquant可能存在API适配问题，更新到最新版本：

  install.packages("tidyquant")
  

• 模拟浏览器请求头
  部分API会拦截非浏览器的请求，可手动设置User-Agent模拟浏览器：

  # 定义自定义请求头
  ua <- user_agent("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36")
  
  # 用httr直接请求API，再解析数据
  response <- GET("https://api.nasdaq.com/api/screener/stocks?tableonly=true&exchange=nasdaq&download=true", ua, timeout(120))
  data <- fromJSON(content(response, "text"))
  NASDAQ <- data$data$table$rows %>% 
    as_tibble() %>% 
    add_column(exchange = "NASDAQ")
  

• 添加重试机制
  临时网络波动可能导致超时，用tryCatch或purrr::possibly实现重试：

  library(purrr)
  # 定义带重试的获取函数
  get_exchange_data <- possibly(function(exchange_name) {
    tq_exchange(exchange_name) %>% add_column(exchange = exchange_name)
  }, otherwise = NULL)
  
  # 重试3次
  NASDAQ <- NULL
  for (i in 1:3) {
    NASDAQ <- get_exchange_data("NASDAQ")
    if (!is.null(NASDAQ)) break
    Sys.sleep(2) # 每次重试间隔2秒
  }
  

内容的提问来源于stack exchange，提问作者ebrahimi