How to Rename an R Object

How do I rename an R object?

Renaming an object and the colnames within it is a two step process:

SPY <- GSPC # assign the object to the new name (creates a copy)
colnames(SPY) <- gsub("GSPC", "SPY", colnames(SPY)) # rename the column names

Otherwise, the getSymbols function allows you to not auto assign, in which case you could skip the first step (you will still need to rename the columns).

SPY <- getSymbols("^GSPC", auto.assign=FALSE)

---

Comment from @backlin

R employs so-called lazy evaluation. An effect of that is that when you "copy" SPY <- GSPC you do not actually allocate new space in the memory for SPY. R knows the objects are identical and only makes a new copy in the memory if one of them is modified (i.e. when they are no longer the identical, e.g. when you change the column names on the following line). So by doing

SPY <- GSPC
rm(GSPC)
colnames(SPY) <- gsub("GSPC", "SPY", colnames(SPY))

you never really copy GSPC but merely give it a new name (SPY) and then tell R to forget the first name (GSPC). When you then change the column names you do not need to create a new copy of SPY since GSPC no longer exists, meaning you have truly renamed the object without creating intermediate copies.

Rename objects in environment r

If you can’t assign them directly with the correct name, then the easiest is to replace the environment by a new one. If you absolutely need to preserve the environment (because it’s referenced elsewhere), you can replace its contents using the same trick:

objs = mget(ls(env), env)
rm(list = ls(env), envir = env)
list2env(setNames(objs, new_names), env)

The relevant part here is the last parameter to list2env: if you leave it off, this just creates a new environment. If you specify an existing environment, the names are added to that instead.

This code will leave hidden names (i.e. names starting with .) untouched — to change this, provide the all.names argument to ls, or use names.

How to rename a variable in R without copying the object?

R is smart enough not to make a copy if the variable is the same, so just go ahead, reassign and rm() the original.

Example:

x <- 1:10
tracemem(x)
# [1] "<0000000017181EA8>"
y <- x
tracemem(y)
# [1] "<0000000017181EA8>"

As we can see both objects point to the same address. R makes a new copy in the memory if one of them is modified, i.e.: 2 objects are not identical anymore.

# Now change one of the vectors
y[2] <- 3
# tracemem[0x0000000017181ea8 -> 0x0000000017178c68]: 
# tracemem[0x0000000017178c68 -> 0x0000000012ebe3b0]: 
tracemem(x)
# [1] "<0000000017181EA8>"
tracemem(y)
# [1] "<0000000012EBE3B0>"

Related post: How do I rename an R object?

Using an object to rename a variable in R

You can use {{new_name}}

new_name <- paste("New","Name")

as.data.frame(state.x77) %>% 
  rename({{new_name}}:=Population) %>% 
  head()

           New Name Income Illiteracy Life Exp Murder HS Grad Frost   Area
Alabama        3615   3624        2.1    69.05   15.1    41.3    20  50708
Alaska          365   6315        1.5    69.31   11.3    66.7   152 566432
Arizona        2212   4530        1.8    70.55    7.8    58.1    15 113417
Arkansas       2110   3378        1.9    70.66   10.1    39.9    65  51945
California    21198   5114        1.1    71.71   10.3    62.6    20 156361
Colorado       2541   4884        0.7    72.06    6.8    63.9   166 103766

Alternatively, you can do this

state = as.data.frame(state.x77)
colnames(state)[which(colnames(state)=="Population")] <- new_name
head(state)

           New Name Income Illiteracy Life Exp Murder HS Grad Frost   Area
Alabama        3615   3624        2.1    69.05   15.1    41.3    20  50708
Alaska          365   6315        1.5    69.31   11.3    66.7   152 566432
Arizona        2212   4530        1.8    70.55    7.8    58.1    15 113417
Arkansas       2110   3378        1.9    70.66   10.1    39.9    65  51945
California    21198   5114        1.1    71.71   10.3    62.6    20 156361
Colorado       2541   4884        0.7    72.06    6.8    63.9   166 103766

How to rename objects in R based on function arguments?

In R, you can't return a vector called something. If you want a vector called vector_1 to just appear after you call the function without having to store it anywhere, you need to use assign or the <<- operator inside the function. This usually isn't a good idea.

However, it is a good idea to have named vectors inside a list, and this can be done simply without using a loop at all:

indexed_vector <- function(df, i) setNames(as.list(df[i]), paste0("vector_", i))

df <- data.frame(a = 1:3, b = 4:6, c = 7:9, d = 10:12)

indexed_vector(df, 1:3)
#> $vector_1
#> [1] 1 2 3
#> 
#> $vector_2
#> [1] 4 5 6
#> 
#> $vector_3
#> [1] 7 8 9

^{Created on 2020-06-11 by the reprex package (v0.3.0)}

r - Rename R object while save()-ing it

This proved to be a little trickier that I expected. I'll be interested to see what others come up with, and also what any objections to my solution may be.

saveit <- function(..., file) {
  x <- list(...)
  save(list=names(x), file=file, envir=list2env(x))
}

foo <- 1
saveit(bar=foo, file="hi.Rdata")

Name or rename list object in R with str_c() or paste()

Use either setNames or

append(all_output, setNames(list(params), str_c("this_", "does_", "not_", "work")))

-output

$this_works_fine
# A tibble: 3 × 2
   col1 col2 
  <dbl> <chr>
1     1 a    
2     2 b    
3     3 c    

$this_does_not_work
# A tibble: 3 × 2
   col1 col2 
  <dbl> <chr>
1     1 a    
2     2 b    
3     3 c    

or use lst from dplyr with :=

append(all_output, lst(!!str_c("this_", "does_", "not_", "work") := params))

-output

$this_works_fine
# A tibble: 3 × 2
   col1 col2 
  <dbl> <chr>
1     1 a    
2     2 b    
3     3 c    

$this_does_not_work
# A tibble: 3 × 2
   col1 col2 
  <dbl> <chr>
1     1 a    
2     2 b    
3     3 c    

R rename an object / data.frame without intermediary object

@landroni answered the question. Here's an example showing that this is indeed how R works.

# copy an object to a new variable name, no change in memory usage
rm(list=ls())
gc()
memory.size()
# [1] 40.15
big.obj <- seq(1e7)
memory.size()
# [1] 78.34
big.obj.renamed <- big.obj
memory.size()
# [1] 78.34
rm(big.obj)
memory.size()
# [1] 78.34

# if the first variable is modified, however, you see the evidence of a hard copy
rm(list=ls())
gc()
memory.size()
# [1] 40.15
big.obj <- seq(1e7)
memory.size()
# [1] 78.34
big.obj.renamed <- big.obj
memory.size()
# [1] 78.34
big.obj[1] <- 2 # modifying the original forces hard copy
memory.size()
# [1] 192.8

Rename objects in for loop in R

Another option is to use assign

for ( i in 1:10) {
                 assign(paste0("plot", i),  ggplot(data, aes(x=data[,i], fill=Group)) +
                                                   geom_histogram(binwidth=200, alpha=.5, position="dodge") )
                 }

This will create each plot as a different object (plot1, plot2, plot3 ... ) in your global environment

---

Related Topics