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

[PIKAL Petr]

Hi



Keep your mails on the list. Actually you did not say much about your data and 
the way how do you want to model them. There are plenty of modelling functions 
in R starting with e.g. lm but I am not aware of a procedure in which you just 
design your explanatory variables to set plausible model. But I am not expert 
in statistics and this list is not ment for solving statistical problems.



Cheers

Petr





From: Shah Alam <dr.alamsolangi using gmail.com>
Sent: Monday, April 19, 2021 5:20 PM
To: PIKAL Petr <petr.pikal using precheza.cz>
Subject: Re: [R] What is an alternative to expand.grid if create a long 
vector?



Dear Petr,



Thanks for your response. I am designing a model with 10 unknown parameters. 
generating the combination of unknown parameters will be used in the model to 
estimate the set of vectors that fits well to actual data. Is there any other 
was to do it? I also used randomLHS function from lhs package. But, it did not 
serve the purpose.



Best regards,

Shah Alam





On Mon, 19 Apr 2021 at 16:07, PIKAL Petr <petr.pikal using precheza.cz 
<mailto:petr.pikal using precheza.cz> > wrote:

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 
> <mailto: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 <mailto: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>  <http://rep.int>(rep.int 
> <http://rep.int>  <http://rep.int>(seq_len(nx),
> rep.int <http://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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