Dear All,
I have a data set with variables x1, x2, x3, ..., x20 and I want to
create z1, z2, z3, ..., z20 with the following formula:
z1 = 200 - x1
z2 = 200 - x2
z3 = 200 - x3
.
.
.
z20 = 200 - x20.
I tried using a for loop and its index as:
for (i in 1:20) {
z(i) = 200 - x(i)
}
But R gives the following error message: "Error: could not find function "x"".
Is there any other way for a simple coding of my 20 lines of code?
Alohas,
Hassan Eini-Zinab
For loop and using its index
5 messages · Hassan Eini Zinab, PIKAL Petr, Milan Bouchet-Valat +2 more
Hi
Dear All,
I have a data set with variables x1, x2, x3, ..., x20 and I want to
create z1, z2, z3, ..., z20 with the following formula:
z1 = 200 - x1
z2 = 200 - x2
z3 = 200 - x3
.
.
.
z20 = 200 - x20.
I tried using a for loop and its index as:
for (i in 1:20) {
z(i) = 200 - x(i)
}
But R gives the following error message: "Error: could not find function
"x"". You probably did not define any such function.
Is there any other way for a simple coding of my 20 lines of code?
No. Preferable is to do it in one line z <- x-200 But it depends what is a set of variables. There is no such object in R AFAIK.
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Regards Petr
Alohas, Hassan Eini-Zinab
______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Le vendredi 09 mars 2012 ? 13:24 +0330, Hassan Eini Zinab a ?crit :
Dear All,
I have a data set with variables x1, x2, x3, ..., x20 and I want to
create z1, z2, z3, ..., z20 with the following formula:
z1 = 200 - x1
z2 = 200 - x2
z3 = 200 - x3
.
.
.
z20 = 200 - x20.
I tried using a for loop and its index as:
for (i in 1:20) {
z(i) = 200 - x(i)
}
But R gives the following error message: "Error: could not find function "x"".
Is there any other way for a simple coding of my 20 lines of code?
This is very basic, please read the R intro.
The problem is that x(i) means "call function x with argument i", and no
function x exists (nor z, BTW). You need
x1 <- 1:10
x2 <- 11:20
for (i in 1:2) {
assign(paste("z", i, sep=""), 200 - get(paste("x", i, sep="")))
}
But you'd better use a data frame to store these variables, in which
case you can do:
df <- data.frame(x1=1:10, x2=11:20)
for (i in 1:2) {
df[[paste("z", i, sep="")]] <- 200 - df[[paste("x", i, sep="")]]
}
You can also create a new data frame:
xdf <- data.frame(x1=1:10, x2=11:20)
zdf <- 200 - xdf
colnames(zdf) <- paste("z", 1:2, sep="")
df <- cbind(xdf, zdf)
Regards
On Fri, Mar 09, 2012 at 01:24:00PM +0330, Hassan Eini Zinab wrote:
Dear All,
I have a data set with variables x1, x2, x3, ..., x20 and I want to
create z1, z2, z3, ..., z20 with the following formula:
z1 = 200 - x1
z2 = 200 - x2
z3 = 200 - x3
.
.
.
z20 = 200 - x20.
I tried using a for loop and its index as:
for (i in 1:20) {
z(i) = 200 - x(i)
}
Hi. Try this. x <- 21:40 z <- 200 - x x[1] # [1] 21 x[2] # [1] 22 z[1] # [1] 179 z[2] # [1] 178 Hope this helps. Petr Savicky.
Hassan,
Others have provided you with better solutions, but I hope this allows you
to see why yours didn't work.
# first (going with your code) you needed a data.frame called "x"
# here is an example:
x <- structure(list(x1 = c(0.0986048226696643, -0.445652024980979,
0.0893989676314604, -3.02656448303247, -0.966125836458264,
-1.49916656636977,
-1.43173455089552, 0.370528111260298, -1.16980816517156, -0.808744946153693
), x2 = c(-0.765406771195136, -0.37933377428095, 1.38846324586498,
-1.70043724374807, -0.71331175577977, 1.44597103991061, 1.31674350467787,
-0.954578441470943, -1.30637013925954, 0.551870274117374), x3 =
c(-0.122350075070145,
1.6217818199546, -0.824570718637696, -0.0341988842898353, 1.03924814479596,
0.898533448980663, 0.68074228601446, 0.296251937506574, -0.698501590358135,
-0.0533564535030227)), .Names = c("x1", "x2", "x3"), row.names = c(NA,
-10L), class = "data.frame")
# you then need an empty vector to hold the results of your for loop (called
"z" here)
# note the square brackets as opposed to your parentheses
z <- vector("list")
for (i in 1:ncol(x)) {
z[i] = 200 - x[i]
}
# finally, this will reassemble the output of the for loop
z <- do.call(cbind, z)
colnames(z) <- c("z1", "z2", "z3")
# Finally, do read what the others sent you as they provide more efficient
solutions
HTH
Chuck
Hassan Eini Zinab wrote
Dear All,
I have a data set with variables x1, x2, x3, ..., x20 and I want to
create z1, z2, z3, ..., z20 with the following formula:
z1 = 200 - x1
z2 = 200 - x2
z3 = 200 - x3
.
.
.
z20 = 200 - x20.
I tried using a for loop and its index as:
for (i in 1:20) {
z(i) = 200 - x(i)
}
But R gives the following error message: "Error: could not find function
"x"".
Is there any other way for a simple coding of my 20 lines of code?
Alohas,
Hassan Eini-Zinab
______________________________________________ R-help@ mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
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