R help - Mar 2006 - Multi-line paste function

Here's my contribution to R.

When R interacts with external programs (MySQL, cURL, etc.), it often
requires a pasted string that is sent to these programs. For readability
reasons, it is often preferable to have complex commands (SQL for example)
spread on several lines. However, the normal paste function requires to add
additional ' ", ' at the end of each line and another ' "
' at the beginning
of each new line.  It becomes fastidious for long commands.

Multi-line paste function:

multi.line.paste <-function (..., sep = " ", collapse = NULL) 
{
    args <- list(...)
    if (length(args) == 0) 
        if (length(collapse) == 0) 
            character(0)
        else ""
    else {
        for (i in seq(along = args)) args[[i]] <-
gsub("\n","",as.character(args[[i]]))
        .Internal(paste(args, sep, collapse))
    }
}

Example with a SQL command on multiple lines:

multi.line.paste("
SELECT * 
FROM estimates a, newtable b 
WHERE a.Ticker=b.Ticker 
AND a.Fiscal_Year=b.Fiscal_Year 
AND a.EPS<>b.EPS 
AND a.Date_Last_change-1.9>b.Date_Last_change
")

Regards,

Pierre


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I am not sure I clearly understand what you want, but getting the string 
returned by your multi.line.paste() function is straightforward using 
gsub():

gsub("\n", "", "
SELECT *
FROM estimates a, newtable b
WHERE a.Ticker=b.Ticker
AND a.Fiscal_Year=b.Fiscal_Year
AND a.EPS<>b.EPS
AND a.Date_Last_change-1.9>b.Date_Last_change
")

If you really want a custom function for that, then, define:

multi.line.paste <- function(str) gsub("\n", "", str)

Best,

Philippe Grosjean

Lapointe, Pierre wrote:
> Here's my contribution to R.
> 
> When R interacts with external programs (MySQL, cURL, etc.), it often
> requires a pasted string that is sent to these programs. For readability
> reasons, it is often preferable to have complex commands (SQL for example)
> spread on several lines. However, the normal paste function requires to add
> additional ' ", ' at the end of each line and another '
" ' at the beginning
> of each new line.  It becomes fastidious for long commands.
> 
> Multi-line paste function:
> 
> multi.line.paste <-function (..., sep = " ", collapse = NULL) 
> {
>     args <- list(...)
>     if (length(args) == 0) 
>         if (length(collapse) == 0) 
>             character(0)
>         else ""
>     else {
>         for (i in seq(along = args)) args[[i]] <-
> gsub("\n","",as.character(args[[i]]))
>         .Internal(paste(args, sep, collapse))
>     }
> }
> 
> Example with a SQL command on multiple lines:
> 
> multi.line.paste("
> SELECT * 
> FROM estimates a, newtable b 
> WHERE a.Ticker=b.Ticker 
> AND a.Fiscal_Year=b.Fiscal_Year 
> AND a.EPS<>b.EPS 
> AND a.Date_Last_change-1.9>b.Date_Last_change
> ")
> 
> Regards,
> 
> Pierre
> 
> 
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> 
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> 
>

Hello Phillipe

1-You are right that for a simple example as the one I provided, paste and
gsub give the same result.
2-For a more complex case, where let's say, I'd like to include a
variable
in my SQL statement, the multi.line.paste command is essential.

variable <-1.9
multi.line.paste("
SELECT * 
FROM estimates3 a, newtable b 
WHERE a.Ticker=b.Ticker 
AND a.Fiscal_Year=b.Fiscal_Year
AND a.EPS<>b.EPS 
AND
a.Date_Last_change_or_conf-",variable,">b.Date_Last_change_or_conf
",sep="")

Regards,

Pierre 

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