Using read.csv.sql to select multiple values from a single column

Question

I am using read.csv.sql from the package sqldf to try and read in a subset of rows, where the subset selects from multiple values - these values ar

Answer 1

You could use deparse, but I'm not sure it's much cleaner than what you already have:

read.csv.sql("mtcars.csv",
             sql = paste("select * from file where carb in ", gsub("c","",deparse(cc)) ))

And note that this is not really a general solution, because deparse will not always give you the right character string. It just happens to work in this instance.

Answer 2

1) fn$ Substitution can be done with fn$ of gsubfn (which is automatically pulled in by sqldf). See the fn$ examples on the sqldf home page. In this case we have:

fn$read.csv.sql("mtcars.csv", 
  sql = "select * from file where carb in ( `toString(cc)` )")

2) join Another approach would be to create a data.frame of the carb values desired and perform a join with it:

Carbs <- data.frame(carb = cc)
read.csv.sql("mtcars.csv", sql = "select * from Carbs join file using (carb)")