[R] recoding data with loops

[Bert Gunter]

If you're serious, start by reading the docs, especially "An Introduction to
R." There are also other learning resources listed on CRAN.  

-- Bert gunter
Genentech

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Donald Braman
Sent: Monday, May 19, 2008 12:42 PM
To: r-help at r-project.org
Subject: [R] recoding data with loops

# I'm new to R and am trying to get the hang of how it handles
# dataframes & loops. If anyone can help me with some simple tasks,
# I'd be much obliged.

# First, i'd like to generate some random data in a dataframe
# to efficiently illustrate what I'm up to.
# let's say I have six variables as listed below (I really
# have hundreds, but a few will illustrate the point).
# I want to generate my dataframe (mdf)
# with the 6 variables X 100 values with rnorm(7).
# How do I do this?  I tried many variations on the following:

var_list <- c("HEQUAL", "EWEALTH", "ERADEQ", "HREVDIS1", "EDISCRIM",
"HREVDIS2")
for(i in 1:length(var_list)) {var_list[1] <- rnorm(100)}
mdf <- data.frame(cbind(varlist[1:length(var_list)])
mdf


# Then, I'd like to recode the variables that begin with the letter "H".
# I've tried many variations of the following, but to no avail:

reverse_list <- c("HEQUAL", "HREVDIS1", "HREVDIS2")
reversed_list <- c("RHEQUAL", "RHREVDIS1", "RHREVDIS2")
for(i in 1:length(reverse_list))
 {mdf[ ,e_reversed_list][[i]] <- recode(mdf[ ,e_reverse_list][[i]],
'5:99=NA; 1=4; 2=3; 3=2; 4=1; ', as.factor.result=FALSE)

# I'm sure I have many deep misunderstandings about the R language, but
# if I can get this much done, I think I'll be well on my way to
understanding R
# and how it works with loops and dataframes.

# Thanks!

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