【发布时间】：2016-02-18 16:05:03
【问题描述】：
我正在尝试自动化一个简单的过程，即导入一些数据并使用 tidyr 包中的扩展函数使其成为宽格式数据。
下面是一个简化的例子
Ticker <- c(rep("GOOG",5), rep("AAPL",5))
Prices <- rnorm(10, 95, 5)
Date <- rep(sapply(c("2015-01-01", "2015-01-02", "2015-01-03", "2015-01-04", "2015-01-05"),as.Date), 2)
exStockData <- data.frame(Ticker, Date, Prices)
在读取 exStockData 之类的数据框后，我希望能够创建如下所示的数据框
library(tidyr)
#this is the data frame I'd like to be able to create
desiredDataFrame <- spread(exStockData, Ticker, Prices)
但是，用于扩展函数的键参数的列并不总是称为 Ticker，而用于函数的 value 参数的列也不总是称为价格。列名是从导入的文件的不同部分读入的。
#these vectors are removed because the way my text file is read in
#I don't actually have these vectors
rm(Ticker, Prices, Date)
#the name of the first column (which serves as the key in
#the spread function) of the exStockData data frame will
#vary, and is read in from the file and stored as a one
#element character vector
secID <- "Ticker"
#the name of the last column in the data frame
#(which serves as the value in the spread function)
#is stored also stored as a one element character vector
fields <- "Prices"
#I'd like to be able to dynamically specify the column
#names using these other character vectors
givesAnError <- spread(exStockData, get(secID), get(fields))
【问题讨论】：
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?spread的文档将您引向专门用于此目的的?spread_。 -
这既方便又尴尬。谢谢！
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@user1583016，您可以发布解决方案作为您自己问题的答案并接受它，或者删除该问题。如果我没记错的话，这会记录在帮助文件中并作为小插曲的一部分。 （除非 joran 想发布答案....）
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我继续发布了答案。不过我不能再接受两天了。