R help - Jul 2011 - Display/show the evaluation result of R commands automatically

Hello R-help,

I wonder if it is possible to configure R, so that it will
display/show the evaluation result of the R commands automatically
(similar to the behavior of Matlab)

i.e. If I type x <- 8

it will print 8 in the command prompt, instead of having type x
explicitly to show the result and perhaps put an ";" at the end to
suppress the output.

i.e. x <- 8;

Thank you

Anthony

> h <- taskCallbackManager()
> h$add(function(expr, value, ok, visible) {if(!visible){print(value)};TRUE})

On Sun, Jul 31, 2011 at 12:15 PM, Anthony Ching Ho Ng
<anthony.ch.ng at gmail.com> wrote:
> Hello R-help,
>
> I wonder if it is possible to configure R, so that it will
> display/show the evaluation result of the R commands automatically
> (similar to the behavior of Matlab)
>
> i.e. If I type x <- 8
>
> it will print 8 in the command prompt, instead of having type x
> explicitly to show the result and perhaps put an ";" at the end
to
> suppress the output.
>
> i.e. x <- 8;
>
The first thing I think you can do by adding a task callback manager
to print the value if the value would otherwise be invisible:

 > h <- taskCallbackManager()
 > h$add(function(expr, value, ok, visible)
{if(!visible){print(value)};TRUE})

 The semicolon thing would probably need rewriting bits of R at the C
code level.

 I don't think many people would use it though. And my code above
might break things. I don't use it.

Barry

On 11-07-31 7:15 AM, Anthony Ching Ho Ng wrote:
> Hello R-help,
>
> I wonder if it is possible to configure R, so that it will
> display/show the evaluation result of the R commands automatically
> (similar to the behavior of Matlab)
It's open source so in theory anything is possible, but there's no 
built-in support for that.
> i.e. If I type x<- 8
>
> it will print 8 in the command prompt, instead of having type x
> explicitly to show the result and perhaps put an ";" at the end
to
> suppress the output.
>
> i.e. x<- 8;
If you wrap the assignment in parens the result is made visible, e.g.

(x <- 8)

will print if you enter it in the console.  (It won't print if it's a 
line in a function; there you need an explicit call to print().  Only 
the value returned at the top level is eligible for auto-printing.)

Duncan Murdoch

On Sun, Jul 31, 2011 at 7:15 AM, Anthony Ching Ho Ng
<anthony.ch.ng at gmail.com> wrote:
> Hello R-help,
>
> I wonder if it is possible to configure R, so that it will
> display/show the evaluation result of the R commands automatically
> (similar to the behavior of Matlab)
>
> i.e. If I type x <- 8
>
> it will print 8 in the command prompt, instead of having type x
> explicitly to show the result and perhaps put an ";" at the end
to
> suppress the output.
>
> i.e. x <- 8;
>
Not quite the same but perhaps good enough is that at the console this
will give you the last value:

.Last.value


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