On Sun, Jul 12, 2009 at 1:05 PM, David Winsemius<dwinsem...@comcast.net> wrote:
>
> On Jul 12, 2009, at 3:35 PM, David Winsemius wrote:
>
>>
>> On Jul 12, 2009, at 2:53 PM, Mark Knecht wrote:
>>
>>>
>>> As a test I tried to print down to the string "(all)" and then
>>> break but this code and everything I've tried so far is terribly
>>> wrong. Every attempt prints lots of error messages. I'm not grasping
>>> at all what I'm doing wrong or what's the right way to do this sort of
>>> thing. Clearly my first for loop isn't a success!
>>>
>>> for(n in SystemResults$EnTime) {
>>> if(SystemResults$EnTime[n] == "(all)") break)
>>
>> Inside the loop, shouldn't you be comparing to "n"?? As you have it now,
>> the values of that factor are probably being used as indices to itself. (Not
>> good.) Also not good is the use of "break". It looks to be fairly severely
>> deprecated at this point
>
> Appears I am wrong about this. I was basing my assumption on this
> interaction with the R interpreter:
>> ?break
> Error in genericForPrimitive(f) :
> methods may not be defined for primitive function "break" in this version
> of R
>
> But:
>
> ?Control ... suggests that break-ing out of for loops remains acceptable.
>
>
> David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
>
>
Hi David,
Thanks for the response. It is helping.
I think the break is required as your suggestion doesn't exit the
loop i there is more data like mine. It just skips printing the (all)
but incorrectly prints the other copies down lower in the data frame:
> tf <- factor(c(53 , 906 , 919 , 932 , 945 , 958 , 1011 , 1024 ,
> "(all)", 53 , 906 , 919 , 932 , 945 , 958 , 1011 , 1024 , "(all)" ) )
> for(n in tf ) {if (n != "(all)") print(n)}
[1] "53"
[1] "906"
[1] "919"
[1] "932"
[1] "945"
[1] "958"
[1] "1011"
[1] "1024"
[1] "53"
[1] "906"
[1] "919"
[1] "932"
[1] "945"
[1] "958"
[1] "1011"
[1] "1024"
>
whereas the else break gets me out:
> tf <- factor(c(53 , 906 , 919 , 932 , 945 , 958 , 1011 , 1024 ,
> "(all)", 53 , 906 , 919 , 932 , 945 , 958 , 1011 , 1024 , "(all)" ) )
> for(n in tf ) {if (n != "(all)") print(n) else break}
[1] "53"
[1] "906"
[1] "919"
[1] "932"
[1] "945"
[1] "958"
[1] "1011"
[1] "1024"
>
My confusion here is really how the 'n' is being used. I thought it
was just an index - a number that gets used inside of the curly braces
like other languages I've used. It seems it isn't that at all but
really operates as something that returns the actual value of the
position in the factor. I was trying to reference the location in the
list but for is already returning the value. Strange, but I'm sure
there are good reasons. Please note that I anot a prgrammer and have
no formal training so it hardly matters what I think! :-)
I'm now wondering if I'd be better off to try using ?match to find the
first position of "(all)" instead of using the for loop? If match
returned a number then I think I'd be more comfortable, but maybe I
should keep going the way I am.
It seems I'm maybe getting the getting the correct answer now but I'm
concerned that it's coming back with quotes. I can get around that
using
print(as.integer(x))
but all this coercion stuff that R is doing is giving me fits. I just
don't have my head around it yet. None the less R is already giving me
visibility into my data that I've not had before so overall the
results are strongly positive.
Thanks,
Mark
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
