Subsetting a List in R where not a value

Question

I'm having trouble "filtering" a list in R because I don't have specific parameters. The function i've created will evaluate 4000 html strings and "decide" if it is a valid or not address:

Tree<-lapply(TreeList,ValURL)
#Returns a list with "Error" or a html string in each element (about 4000 elements total). 

I want to create a subset of the Tree list with only the elements that are NOT "Error".I'm used to SQL, so it would be something like:

SELECT * FROM Tree WHERE Column1!="Error"

Obviously it's different in R but I can't seem to get it. I've been trying (to no avail):

 Tree$"Error"

Help!

Answer 1

Assuming your Tree looks kind of like this

Tree<-list(
    "Error",
    "<p>Hello</p>",
    "<h1>Heading</h1>",
    "Error",
    "<strong>Bold</strong"
)

then this should work:

Tree[Tree != "Error"]