Assigning strings to a data frame as variables

Question

See below

for(stockName in c("AAPLstock", "FBstock", "GOOGstock", "HPQstock", "MSFTstock", "YHOOstock")){
assign(paste(stockName), read.table(paste(stockName,'.txt', sep = ""), quote="\"", comment.char=""))  }

This creates these variables. Which is all cool

ls(pattern = "stock")
[1] "AAPLstock" "FBstock"   "GOOGstock" "HPQstock"  "MSFTstock"
[6] "stockName" "YHOOstock"

When I try to assign all of them to a data frame like below

df<-list(ls(pattern = "stock"))
> df
[[1]]
[1] "AAPLstock" "FBstock"   "GOOGstock" "HPQstock"  "MSFTstock"
[6] "stockName" "YHOOstock"

What I want is for df to contain these stocks as variables, not as strings. So the function below gives me the desired result

df <- list(AAPLstock, FBstock, GOOGstock, HPQstock, MSFTstock, YHOOstock)

But that requires me to type out all the variables. The thing is, I am going to be doing that but with more stocks, and I don't want to type the name of a 100 variables, and it's going to be a pain to change. So I want a way to assign strings that represent variables to a data frame using ls() or something similar.

I have tried Parse and assign, but they still assigned df strings rather than variables.

Why not skip using assign altogether, and create a named list using lapply over your vector of stocknames? — Heroka
– Heroka, Commented Apr 30, 2016 at 7:26
lapply(stockNameVector, function(stockName) read.table(paste(... ) — Richard Telford
– Richard Telford, Commented Apr 30, 2016 at 7:41

Parfait · Accepted Answer · 2016-04-30 20:27:55Z

1

Consider using mget() to pull multiple variables by string reference.

df <- data.frame(mget(ls(pattern = "stock")), stringsAsFactors =  FALSE)

But as mentioned also consider building a running list of stocks and rbind to a dataframe:

stockName <- c("AAPLstock", "FBstock", "GOOGstock", "HPQstock", "MSFTstock", "YHOOstock")
listOfStocks <- lapply(stockName, 
                       function(s) { 
                             read.table(paste(s,'.txt', sep = ""), 
                                        quote="\"", comment.char="")
                       })
df <- do.call(rbind, listOfStocks)

edited Apr 30, 2016 at 20:27

answered Apr 30, 2016 at 20:13

Parfait

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