19 Dec
2004
19 Dec
'04
8:35 a.m.
Suppose I have several dataframes: g1, g2, g3....
Each as the same variable names: X, Y....
I want to write a function that can deal with variables across the
dataframes. The easiest way that I can think of to do it would be to
write a function that could walk through each dataframe and do stuff
to the variables, something like:
mush.data <- function(varname, numgroups) {
for(i in 1:numgroups) {
SomeFunction(paste("g", i, "$",varname)
}
BUT - paste just gives me a string. How do I get R to realize that
it's actually pointing to a vector? I feel that R should let me do
this, right?
Any help would be greatly appreciated.
/\llan
19 Dec
19 Dec
9:02 a.m.
Use the index number on the variable. Remember that a data
frame is just like a list, and you have a list of data frames.
Let's call the list of data frames "datas":
results <- list()
for (j in 1:length(variables)) {
for (i in 2:length(groups)) {
var.across.data <- datas[[1]][[j]]
var.across.data <- c(var.across.data, datas[[i]][[j]])
}
results[[j]] <- do.stuff(var.across.data)
}
Note the order of the nested loop. You want to do something
across data frames, by variable, so the variables go on the
outside loop.
----- Original Message -----
From: "Allan Friedman" <allan.friedman(a)gmail.com>
To: <gov2001-l(a)lists.fas.harvard.edu>
Sent: Sunday, December 19, 2004 1:35 PM
Subject: [gov2001-l] dynamic variable names in R?
Suppose I have several dataframes: g1, g2, g3....
Each as the same variable names: X, Y....
I want to write a function that can deal with variables across
the
dataframes. The easiest way that I can think of to do it
would be to
write a function that could walk through each dataframe and do
stuff
to the variables, something like:
mush.data <- function(varname, numgroups) {
for(i in 1:numgroups) {
SomeFunction(paste("g", i, "$",varname)
}
BUT - paste just gives me a string. How do I get R to realize
that
it's actually pointing to a vector? I feel that R should let
me do
this, right?
Any help would be greatly appreciated.
/\llan
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gov2001-l(a)lists.fas.harvard.edu
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20 Dec
20 Dec
7:04 p.m.
Good evening Allan,
I bet what you want is
SomeFunction(g[[i]][names(g[[i]])="varname"])
Kentaro
----- Original Message -----
From: "Allan Friedman" <allan.friedman(a)gmail.com>
To: <gov2001-l(a)lists.fas.harvard.edu>
Sent: Sunday, December 19, 2004 1:35 PM
Subject: [gov2001-l] dynamic variable names in R?
Suppose I have several dataframes: g1, g2, g3....
Each as the same variable names: X, Y....
I want to write a function that can deal with variables across the
dataframes. The easiest way that I can think of to do it would be to
write a function that could walk through each dataframe and do stuff
to the variables, something like:
mush.data <- function(varname, numgroups) {
for(i in 1:numgroups) {
SomeFunction(paste("g", i, "$",varname)
}
BUT - paste just gives me a string. How do I get R to realize that
it's actually pointing to a vector? I feel that R should let me do
this, right?
Any help would be greatly appreciated.
/\llan
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2 comments
3 participants
participants (3)
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allan.friedman＠gmail.com -
fukumoto＠dg8.so-net.ne.jp -
olau＠fas.harvard.edu