Replacing a few variable values within a DataFrame...

From: Phil Spector <spector at stat.berkeley.edu>
Subject: Re: [R] Replacing a few variable values within a DataFrame...
To: "Jason Rupert" <jasonkrupert at yahoo.com>
Date: Monday, March 23, 2009, 12:48 PM
Jason -
    When you say that you want to change some values (if),
but 
leave others the same (else) I think that the else is very 
important.  Here's how to use ifelse to do what you
want:

    test_data2_df$HouseSize = ifelse(test_data2_df$Location
== 'HSV',newvalue, test_data2_df$HouseSize)

Here's another way to selectively change values in a
data frame:

test_data2_df[test_data2_df$Location ==
'HSV','HouseSize'] = newvalues


                                        - Phil Spector
 					 Statistical Computing Facility
 					 Department of Statistics
 					 UC Berkeley
 					 spector at stat.berkeley.edu



On Mon, 23 Mar 2009, Jason Rupert wrote:

I would like to replace a few varaibles within a data

frame.

For example, in the dataframe below (contrived) I

would like to replace the current housesize value only if
the Location is HSV.   However, I would like to leave the
other values intact.

I tried "ifelse", but I don't really

need the else condition.

test_data2_df<-data.frame(Variables=c("SQR

Footage","SQR Footage","SQR
Footage","SQR Footage","SQR
Footage","SQR Footage","SQR
Footage","SQR Footage","SQR
Footage","SQR Footage","SQR
Footage","SQR Footage","SQR
Footage","SQR Footage","SQR
Footage"),HouseSize=c(10, 20, 30, 40, 50, 15, 25, 35,
45, 55, 18, 28, 38, 48, 58), Lot=c(1, 2, 3, 4, 5, 10, 20,
30, 40, 50, 11, 21, 31, 41, 51), Location=c("HSV",
"ATH", "HSV", "ATH",
"FLO",

                                    "HSV",

"ATH", "HSV", "ATH",
"FLO",

                                    "HSV",

"ATH", "HSV", "ATH",
"FLO"))

Moreover, I want to preserve the rest of the values

within the data.  I thought some combination using the
subset would get me there, but I ended up with a long and
ungangly looking code.

Thanks for any help that is offered.