Question

我在数据框中有一个列，包括诸如AAPL（Apple股票），TWTR（Twitter）等股票代码。我正在尝试创建一个新列，它将返回从股票API数据计算出的每个股票代码的股票数量。

但是当我运行下面的代码时，新列“Stock Quantity”为每一行返回了NA。有人有解决方案吗？

library(Quandl)

portfolio <- data.frame(Code=c("AAPL", "TWTR", "MSFT"),
                startingPeriod=c("2015-01-01", "2015-01-01", "2015-01-01"),
                Investment=c("5000", "10000", "15000"), 
                stringsAsFactors=FALSE)


numberofStock <- function(pf) {

API <- Quandl(paste0("WIKI/", pf$Code), type = "raw", 
            start_date = pf$startingPeriod, end_date=Sys.Date())

pf["StockQuantity"] <- floor(pf$Investment_01 / tail(API$Open,1))

return(pf)
}


numberofStock(portfolio)

Answer 1

您可能希望首先使用portfolio$startingPeriod将Date转换为数据类型as.Date。此外，您将两个向量portfolio$Code和portfolio$startingPeriod传递给函数Quandl()。您可能希望尝试使用lapply()函数来迭代这两个函数的每个值。

编辑：您还需要使用portfolio$Investment将numeric转换为as.numeric()。以下是代码的外观：

portfolio <- data.frame(Code=c("AAPL", "TWTR", "MSFT"),
                        startingPeriod=as.Date(c("2015-01-01", "2015-01-01", "2015-01-01")),
                        Investment=as.numeric(c("5000", "10000", "15000")), 
                        stringsAsFactors=FALSE)


numberofStock <- function(pf) {lapply(seq_along(nrow(portfolio)), function(x){
    API <- Quandl(paste0("WIKI/", pf$Code[x]), type = "raw", 
                  start_date = pf$startingPeriod[x], end_date=Sys.Date())

    pf["StockQuantity"] <- floor(pf$Investment[x] / tail(API$Open,1))

    return(pf)
    })
}

numberofStock(portfolio)

Answer 2

这是一个开始。

library(dplyr)

company.initial = 
  portfolio %>%
  mutate(Investment = as.numeric(Investment) ) %>%
  group_by(Code) %>%
  summarize(start_date = min(startingPeriod),
            total_investment = sum(Investment) )

company__date = 
  company.initial %>%
  group_by(Code) %>%
  do(with(.,
     Quandl(paste0("WIKI/", Code), 
            type = "raw",
            start_date = start_date, 
            end_date = Sys.Date() ) ) )

company = 
  company__date %>%
  group_by(Code) %>%
  summarize(last_open = last(Open)) %>%
  left_join(company.initial) %>%
  mutate(StockQuantity = total_investment / last_open)

R中数据帧的每行API调用

2 个答案: