[R] What is an alternative to expand.grid if create a long vector?

[PIKAL Petr]

Hi

Actually expand.grid produces data frame and not vector. And dimension of
the data frame is "big"

> dim(A)
[1] 100000000         4
> str(A)
'data.frame':   100000000 obs. of  4 variables:
 $ Var1: num  0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 ...
 $ Var2: num  1e-04 1e-04 1e-04 1e-04 1e-04 1e-04 1e-04 1e-04 1e-04 1e-04
...
 $ Var3: num  0.38 0.38 0.38 0.38 0.38 0.38 0.38 0.38 0.38 0.38 ...
 $ Var4: num  0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 ...
 - attr(*, "out.attrs")=List of 2
  ..$ dim     : int [1:4] 100 100 100 100
  ..$ dimnames:List of 4
  .. ..$ Var1: chr [1:100] "Var1=0.001" "Var1=0.002" "Var1=0.003"
"Var1=0.004" ...
  .. ..$ Var2: chr [1:100] "Var2=0.0001000000" "Var2=0.0001090909"
"Var2=0.0001181818" "Var2=0.0001272727" ...
  .. ..$ Var3: chr [1:100] "Var3=0.3800000" "Var3=0.3804040"
"Var3=0.3808081" "Var3=0.3812121" ...
  .. ..$ Var4: chr [1:100] "Var4=0.1200000" "Var4=0.1206061"
"Var4=0.1212121" "Var4=0.1218182" ...
>

in case of 4 sequences 1e8 rows, 4 columns
in case of 10 sequences 1e20 rows and 10 columns
in your last example 1.4e8 rows and 10 columns which probably cross the
memory capacity of your PC.

Maybe you could increase memory of you PC. If I am correct to store the
first you need about 3.2GB, to strore the last 11.2 GB.

May I ask what you want to do with such a big object? 

Cheers
Petr

> -----Original Message-----
> From: R-help <r-help-bounces using r-project.org> On Behalf Of Shah Alam
> Sent: Monday, April 19, 2021 2:36 PM
> To: r-help mailing list <r-help using r-project.org>
> Subject: [R] What is an alternative to expand.grid if create a long
vector?
> 
> Dear All,
> 
> I would like to know that is there any problem in *expand.grid* function
or it
> is a limitation of this function.
> 
> I am trying to create a combination of elements using expand.grid
function.
> 
> A <- expand.grid(
> c(seq(0.001, 0.1, length.out = 100)),
> c(seq(0.0001, 0.001, length.out = 100)), c(seq(0.38, 0.42, length.out =
100)),
> c(seq(0.12, 0.18, length.out = 100)))
> 
> Four combinations work fine. However, If I increase the combinations up to
> ten. The following error appears.
> 
>  A <- expand.grid(
> c(seq(0.001, 1, length.out = 100)),
> c(seq(0.0001, 0.001, length.out = 100)), c(seq(0.38, 0.42, length.out =
100)),
> c(seq(0.12, 0.18, length.out = 100)), c(seq(0.01, 0.04, length.out =
100)),
> c(seq(0.0001, 0.001, length.out = 100)), c(seq(0.0001, 0.001, length.out =
> 100)), c(seq(0.001, 0.01, length.out = 100)), c(seq(0.01, 0.3, length.out
= 100))
> )
> 
> *Error in rep.int <http://rep.int>(rep.int <http://rep.int>(seq_len(nx),
> rep.int <http://rep.int>(rep.fac, nx)), orep) :   invalid 'times' value*
> 
> After reducing the length to 10. It produced a different type of error
> 
> A <- expand.grid(
> c(seq(0.001, 0.005, length.out = 10)),
> c(seq(0.0001, 0.0005, length.out = 10)), c(seq(0.38, 0.42, length.out =
5)),
> c(seq(0.12, 0.18, length.out = 7)), c(seq(0.01, 0.04, length.out = 5)),
> c(seq(0.0001, 0.001, length.out = 10)), c(seq(0.0001, 0.001, length.out =
10)),
> c(seq(0.001, 0.01, length.out = 10)), c(seq(0.1, 0.8, length.out = 8))
> )
> 
> *Error: cannot allocate vector of size 1.0 Gb*
> 
> What is an alternative to expand.grid if create a long vector based on 10
> elements?
> 
> With kind regards,
> Shah Alam
> 
> 	[[alternative HTML version deleted]]
> 
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