When using RMySQL to retrieve data from a database, the result is always a data frame. What is the best way to take get the numbers from a column of the data frame into a vector? That is, I just want the column of numbers from the data frame and not the column label. I'm sure this has been done many times, but I'm new to this, so I thought I'd ask. Thanks, - Jason
Extracting a column of numbers from a data frame
2 messages · Jason Horn, Douglas Bates
On 2/20/06, Jason Horn <jhorn at bu.edu> wrote:
When using RMySQL to retrieve data from a database, the result is always a data frame. What is the best way to take get the numbers from a column of the data frame into a vector? That is, I just want the column of numbers from the data frame and not the column label. I'm sure this has been done many times, but I'm new to this, so I thought I'd ask.
You use the "[[" subscripting operator or its short form for use with names, the $ operator. If your data frame is called "df" and you want the third column as a vector use df[[3]] If the name of the column is "foo" you can also use df[["foo"]] The expression df$foo is syntactic sugar for df[["foo"]]