help wrapping findInterval into a function

[Steve E.]

Dear R Community,

I hope you might be able to assist with a small problem creating a function.  I am working with water-quality data sets that contain the concentration of many different elements in water samples.  I need to assign quality-control flags to values that fall into various concentration ranges.  Rather than a web of nested if statements, I am employing the findInterval function to identify values that need to be flagged and to assign the appropriate flag.  The data consist of a sample identifier, the analysis, and corresponding value.  The findInterval function works well; however, I would like to incorporate it into a function so that I can run multiple findInterval functions for many different water-quality analyses (and I have to do this for many dataset) but it seems to fall apart when incorporated into a function.

Run straighforward, the findInterval function works as desired, e.g. below, creating the new CalciumFlag column with the appropriate flag for, in this case, levels of calcium in the water:

WQdata$CalciumFlag <- with(WQdata, ifelse(analysis == "Calcium", (flags <- c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.027, 0.1, 100, Inf))]),""))

However, it does not worked when wrapped in a function (no error messages are thrown, it simply does not seem to do anything):

WQfunc <- function() {
        WQdata$CalciumFlag <- with(WQdata, ifelse(analysis == "Calcium", (flags <- c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.027, 0.1, 100, Inf))]),""))
        }

Calling the function WQfunc() does not produce an error but also does not produce the expected CalciumFlag, it seems to not do anything.

Ultimately, what I need to get to is something like below where multiple findInterval functions for different analyses are included in a single function, then I can concatenate the results into a single column containing all flags for all analyses, e.g.:

WQfunc <- function() {
        WQdata$CalciumFlag <- with(WQdata, ifelse(analysis == "Calcium", (flags <- c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.027, 0.1, 100, Inf))]),""))

        WQdata$SodiumFlag <- with(WQdata, ifelse(analysis == "Sodium", (flags <- c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.050, 0.125, 125, Inf))]),""))

        WQdata$MagnesiumFlag <- with(WQdata, ifelse(analysis == "Magnesium", (flags <- c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.065, 0.15, 75, Inf))]),""))
       
.....etc for additional water-quality analyses...

        }

As an aside, I started working with the findInterval tool from an example that I found online but am not clear as to how the multi-component configuration incorporating brackets actually works, can anyone suggest a good resource that explains this?


I thank you very much for any assistance you may be able to provide.


Regards,
Steve

[David Winsemius]

On Dec 6, 2011, at 11:43 AM, Steve E. wrote:

> Dear R Community,
>
> I hope you might be able to assist with a small problem creating a  
> function.
> I am working with water-quality data sets that contain the  
> concentration of
> many different elements in water samples.  I need to assign quality-
> control
> flags to values that fall into various concentration ranges.  Rather  
> than a
> web of nested if statements, I am employing the findInterval  
> function to
> identify values that need to be flagged and to assign the  
> appropriate flag.

It's probably your use of "with" rather than findInterval. The 'with'  
function sets up an environment and is used mostly in interactive  
session. If you have not passed a dataframe into the function then you  
should use the name of the dataframe and '['.

> The data consist of a sample identifier, the analysis, and  
> corresponding
> value.  The findInterval function works well; however, I would like to
> incorporate it into a function so that I can run multiple findInterval
> functions for many different water-quality analyses (and I have to  
> do this
> for many dataset) but it seems to fall apart when incorporated into a
> function.
>
> Run straighforward, the findInterval function works as desired, e.g.  
> below,
> creating the new CalciumFlag column with the appropriate flag for,  
> in this
> case, levels of calcium in the water:
>
> WQdata$CalciumFlag <- with(WQdata, ifelse(analysis == "Calcium",  
> (flags <-
> c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.027, 0.1,  
> 100,
> Inf))]),""))
>
> However, it does not worked when wrapped in a function (no error  
> messages
> are thrown, it simply does not seem to do anything):
>
> WQfunc <- function() {
> WQdata$CalciumFlag <- with(WQdata, ifelse(analysis == "Calcium",  
> (flags <-
> c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.027, 0.1,  
> 100,
> Inf))]),""))
> }
>
> Calling the function WQfunc() does not produce an error but also  
> does not
> produce the expected CalciumFlag, it seems to not do anything.
>
> Ultimately, what I need to get to is something like below where  
> multiple
> findInterval functions for different analyses are included in a single
> function, then I can concatenate the results into a single column  
> containing
> all flags for all analyses, e.g.:
>
> WQfunc <- function() {
> WQdata$CalciumFlag <- with(WQdata, ifelse(analysis == "Calcium",  
> (flags <-
> c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.027, 0.1,  
> 100,
> Inf))]),""))
>
> WQdata$SodiumFlag <- with(WQdata, ifelse(analysis == "Sodium",  
> (flags <-
> c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.050,  
> 0.125, 125,
> Inf))]),""))
>
> WQdata$MagnesiumFlag <- with(WQdata, ifelse(analysis ==  
> "Magnesium", (flags
> <- c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.065,  
> 0.15, 75,
> Inf))]),""))
>
> .....etc for additional water-quality analyses...
>
> }
>
> As an aside, I started working with the findInterval tool from an  
> example
> that I found online but am not clear as to how the multi-component
> configuration incorporating brackets actually works, can anyone  
> suggest a
> good resource that explains this?
>
>
> I thank you very much for any assistance you may be able to provide.
>
>
> Regards,
> Steve
>
> --
> View this message in context: http://r.789695.n4.nabble.com/help-wrapping-findInterval-into-a-function-tp4165464p4165464.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> [hidden email] 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.

David Winsemius, MD
West Hartford, CT

______________________________________________
[hidden email] 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.

[William Dunlap]

No, the problem is not with "with" but is
that the OP's did not return the modified
data.frame.  He didn't show how the function
was called, but I suspect the usage was like
  f0 <- function() globalDataFrame$newCol <- ...
  f0()
where it should have been
  f1 <- function(dataFrame) {
    dataFrame$newCol <- ...
    dataFrame # return modified dataFrame
  }
  globalDataFrame <- f1(globalDataFrame)

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com

> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On Behalf Of David Winsemius
> Sent: Tuesday, December 06, 2011 12:05 PM
> To: Steve E.
> Cc: [hidden email]
> Subject: Re: [R] help wrapping findInterval into a function
>
>
> On Dec 6, 2011, at 11:43 AM, Steve E. wrote:
>
> > Dear R Community,
> >
> > I hope you might be able to assist with a small problem creating a
> > function.
> > I am working with water-quality data sets that contain the
> > concentration of
> > many different elements in water samples.  I need to assign quality-
> > control
> > flags to values that fall into various concentration ranges.  Rather
> > than a
> > web of nested if statements, I am employing the findInterval
> > function to
> > identify values that need to be flagged and to assign the
> > appropriate flag.
>
> It's probably your use of "with" rather than findInterval. The 'with'
> function sets up an environment and is used mostly in interactive
> session. If you have not passed a dataframe into the function then you
> should use the name of the dataframe and '['.
>
>
> > The data consist of a sample identifier, the analysis, and
> > corresponding
> > value.  The findInterval function works well; however, I would like to
> > incorporate it into a function so that I can run multiple findInterval
> > functions for many different water-quality analyses (and I have to
> > do this
> > for many dataset) but it seems to fall apart when incorporated into a
> > function.
> >
> > Run straighforward, the findInterval function works as desired, e.g.
> > below,
> > creating the new CalciumFlag column with the appropriate flag for,
> > in this
> > case, levels of calcium in the water:
> >
> > WQdata$CalciumFlag <- with(WQdata, ifelse(analysis == "Calcium",
> > (flags <-
> > c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.027, 0.1,
> > 100,
> > Inf))]),""))
> >
> > However, it does not worked when wrapped in a function (no error
> > messages
> > are thrown, it simply does not seem to do anything):
> >
> > WQfunc <- function() {
> > WQdata$CalciumFlag <- with(WQdata, ifelse(analysis == "Calcium",
> > (flags <-
> > c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.027, 0.1,
> > 100,
> > Inf))]),""))
> > }
> >
> > Calling the function WQfunc() does not produce an error but also
> > does not
> > produce the expected CalciumFlag, it seems to not do anything.
> >
> > Ultimately, what I need to get to is something like below where
> > multiple
> > findInterval functions for different analyses are included in a single
> > function, then I can concatenate the results into a single column
> > containing
> > all flags for all analyses, e.g.:
> >
> > WQfunc <- function() {
> > WQdata$CalciumFlag <- with(WQdata, ifelse(analysis == "Calcium",
> > (flags <-
> > c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.027, 0.1,
> > 100,
> > Inf))]),""))
> >
> > WQdata$SodiumFlag <- with(WQdata, ifelse(analysis == "Sodium",
> > (flags <-
> > c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.050,
> > 0.125, 125,
> > Inf))]),""))
> >
> > WQdata$MagnesiumFlag <- with(WQdata, ifelse(analysis ==
> > "Magnesium", (flags
> > <- c("Y", 'Q', "", "A") [findInterval(WQdata$value, c(-Inf, 0.065,
> > 0.15, 75,
> > Inf))]),""))
> >
> > .....etc for additional water-quality analyses...
> >
> > }
> >
> > As an aside, I started working with the findInterval tool from an
> > example
> > that I found online but am not clear as to how the multi-component
> > configuration incorporating brackets actually works, can anyone
> > suggest a
> > good resource that explains this?
> >
> >
> > I thank you very much for any assistance you may be able to provide.
> >
> >
> > Regards,
> > Steve
> >
> > --
> > View this message in context: http://r.789695.n4.nabble.com/help-wrapping-findInterval-into-a-
> function-tp4165464p4165464.html
> > Sent from the R help mailing list archive at Nabble.com.
> >
> > ______________________________________________
> > [hidden email] 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.
>
> David Winsemius, MD
> West Hartford, CT
>
> ______________________________________________
> [hidden email] 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.

______________________________________________
[hidden email] 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.

[Steve E.]

Bill (and David),

Thank you very much for taking the time to respond to my query.

You were right, I was creating and calling the function exactly as you had predicted.  I revised the structure based on your suggestion.  It runs but the output is an array of the flags that are not attached to the data frame, not a new column in the data frame as was my intention.

So, the new configuration I tried was like this (where DataFrame is not a real data frame but just the word "DataFrame"):

WQFlags <- function(DataFrame) {DataFrame$CalciumFlag <- with(DataFrame, ifelse(variable == "CaD_ICP", (dataqualifier <- c("Y", 'Q', "", "A") [findInterval(DataFrame$value, c(-Inf, 0.027, 0.1, 100, Inf))]),""))
}

I called it using:

WaterQualityData <- WQFlags(WaterQualityData)

Again, the output is simply an array of the flags, unattached to a data frame.  Can you suggest a way to modify this to make it work as desired, or, in the worst case, can I attach the resulting array of flag values?


Thank you again!

[David Winsemius]

On Dec 6, 2011, at 5:53 PM, Steve E. wrote:

> Bill (and David),
>
> Thank you very much for taking the time to respond to my query.
>
> You were right, I was creating and calling the function exactly as  
> you had
> predicted.  I revised the structure based on your suggestion.  It  
> runs but
> the output is an array of the flags that are not attached to the  
> data frame,
> not a new column in the data frame as was my intention.
>
> So, the new configuration I tried was like this (where DataFrame is  
> not a
> real data frame but just the word "DataFrame"):
>
> WQFlags <- function(DataFrame) {DataFrame$CalciumFlag <-  
> with(DataFrame,
> ifelse(variable == "CaD_ICP", (dataqualifier <- c("Y", 'Q', "", "A")
> [findInterval(DataFrame$value, c(-Inf, 0.027, 0.1, 100, Inf))]),""))
> }
>
> I called it using:
>
> WaterQualityData <- WQFlags(WaterQualityData)

Unless you provide either the original data or an unambiguous ( at the  
level the R interpreter would see, not at the level of what you see  
when you print a dataframe) description of your data you will get at  
the very best educated guesses. Use str() or dput().

>
> Again, the output is simply an array of the flags, unattached to a  
> data
> frame.  Can you suggest a way to modify this to make it work as  
> desired, or,
> in the worst case, can I attach the resulting array of flag values?

Do you mean "attach" in the sense of using the R function `attach`? If  
so, then please do not. (And please ignore any advice or the examples  
concerning that issue you might get from reading Crawley's text.)


--

Good night.

David Winsemius, MD
West Hartford, CT

______________________________________________
[hidden email] 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.

[Michael Weylandt]

Can't this be fixed by switching with to within? E.g.,

x = data.frame(a = 1:3, b = 4:6)

AddRowSums <- function(df) within(df, d <- a + b)

x <- AddRowSums(x)

print(x)

Michael

On Wed, Dec 7, 2011 at 12:07 AM, David Winsemius <[hidden email]> wrote:

>
> On Dec 6, 2011, at 5:53 PM, Steve E. wrote:
>
>> Bill (and David),
>>
>> Thank you very much for taking the time to respond to my query.
>>
>> You were right, I was creating and calling the function exactly as you had
>> predicted.  I revised the structure based on your suggestion.  It runs but
>> the output is an array of the flags that are not attached to the data
>> frame,
>> not a new column in the data frame as was my intention.
>>
>> So, the new configuration I tried was like this (where DataFrame is not a
>> real data frame but just the word "DataFrame"):
>>
>> WQFlags <- function(DataFrame) {DataFrame$CalciumFlag <- with(DataFrame,
>> ifelse(variable == "CaD_ICP", (dataqualifier <- c("Y", 'Q', "", "A")
>> [findInterval(DataFrame$value, c(-Inf, 0.027, 0.1, 100, Inf))]),""))
>> }
>>
>> I called it using:
>>
>> WaterQualityData <- WQFlags(WaterQualityData)
>
>
> Unless you provide either the original data or an unambiguous ( at the level
> the R interpreter would see, not at the level of what you see when you print
> a dataframe) description of your data you will get at the very best educated
> guesses. Use str() or dput().
>
>
>>
>> Again, the output is simply an array of the flags, unattached to a data
>> frame.  Can you suggest a way to modify this to make it work as desired,
>> or,
>> in the worst case, can I attach the resulting array of flag values?
>
>
> Do you mean "attach" in the sense of using the R function `attach`? If so,
> then please do not. (And please ignore any advice or the examples concerning
> that issue you might get from reading Crawley's text.)
>
>
> --
>
> Good night.
>
> David Winsemius, MD
> West Hartford, CT
>
>
> ______________________________________________
> [hidden email] 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.

______________________________________________
[hidden email] 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.

[Steve E.]

Thanks to everyone for continued assistance with this problem.  I realize that I had not included enough information, hopefully I have done so here.  I attached a dput output of a sample of the data titled 'WaterData' (and str output below).  Below are dput outputs of the function I am trying to get working and the resulting array when I run it.  Unfortunately, Michael, changing 'with' to 'within' did not solve the problem, as running the function in that case produced no discernible output or result.  What I meant by the function now producing an array of values (though the result I am looking for) that are not attached to the data frame, is that they show up separately in a result window (in a similar format to what you get from dput() and are not at all associated with the data frame).  Again, thanks so much!

> dput(WQFunc)
function (dataframe)
{
    dataframe$CalcFlag <- with(dataframe, ifelse(variable ==
        "CaD_ICP", (dataqualifier <- c("Y", "Q", "", "A")[findInterval(dataframe$value,
        c(-Inf, 0.027, 0.1, 100, Inf))]), ""))
}

> str(WaterData)
'data.frame': 126 obs. of  5 variables:
 $ Site          : Factor w/ 6 levels "BV","CB","KP",..: 3 3 3 3 3 3 3 3 3 3 ...
 $ Time          : Factor w/ 84 levels "0:00:00","0:00:52",..: 1 1 1 1 2 5 16 16 19 20 ...
 $ DateCorrectFmt: Factor w/ 9 levels "2010-08-17","2010-08-21",..: 4 8 1 3 8 5 5 8 8 8 ...
 $ variable      : Factor w/ 3 levels "CaD_ICP","NaD_ICP",..: 1 1 1 1 1 1 1 1 1 1 ...
 $ value         : num  0.044 0.1316 0.0101 0.0114 80.13 ...

Below is the output I get if if I run the WQFunc as:
flagged <- WQFunc(WaterData)

> dput(Flagged)
c("Q", "", "Y", "Y", "", "", "", "", "", "", "", "", "", "",
"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
"", "", "", "", "", "", "", "", "", "", "", "", "", "", "", ""
)
>
 

Again, though, 'Flagged' is an array of those values in a output window but are not 'attached' to WaterData.

[Steve E.]

forgot to attach the data setWaterData.txt

[Michael Weylandt]

So I don't know what you are trying to do with your function (and I
might have incidentally messed it up), but within certainly does add
the desired column:

WaterData <- structure(list(Site = structure(c(3L, 3L, 3L, 3L, 3L,
3L), .Label = c("BV",
"CB", "KP", "LA", "MR", "PIE"), class = "factor"), Time = structure(c(1L,
1L, 1L, 1L, 2L, 5L), .Label = c("0:00:00", "0:00:52", "0:01:00",
"0:06:00", "0:07:00", "0:11:00", "0:16:00", "0:21:00", "0:26:00",
"0:36:00", "0:41:00", "0:51:00", "0:56:00", "1:01:00", "1:06:00",
"1:07:00", "1:10:00", "1:11:00", "1:22:00", "1:37:00", "1:52:00",
"10:22:00", "10:37:00", "10:52:00", "11:22:00", "15:55:00", "16:00:00",
"17:25:00", "17:30:00", "18:00:00", "18:05:00", "18:20:00", "18:35:00",
"18:50:00", "19:05:00", "19:20:00", "19:25:00", "19:35:00", "2:07:00",
"2:14:00", "2:16:00", "2:21:00", "2:22:00", "2:26:00", "2:31:00",
"2:36:00", "2:37:00", "2:38:00", "2:44:00", "2:46:00", "2:52:00",
"20:20:00", "20:32:00", "20:35:00", "21:05:00", "21:17:00", "21:20:00",
"21:32:00", "22:05:00", "22:20:00", "22:21:00", "22:32:00", "22:37:00",
"22:42:00", "22:47:00", "22:50:00", "23:16:00", "23:26:00", "23:31:00",
"23:36:00", "23:41:00", "23:46:00", "23:51:00", "23:56:00", "3:07:00",
"3:22:00", "3:52:00", "4:22:00", "4:52:00", "5:22:00", "6:37:00",
"6:57:00", "7:52:00", "9:22:00"), class = "factor"), DateCorrectFmt =
structure(c(4L,
8L, 1L, 3L, 8L, 5L), .Label = c("2010-08-17", "2010-08-21", "2010-08-22",
"2010-08-28", "2010-08-29", "2010-09-21", "2010-09-22", "2010-10-21",
"2011-02-19"), class = "factor"), variable = structure(c(1L,
1L, 1L, 1L, 1L, 1L), .Label = c("CaD_ICP", "NaD_ICP", "ZnD_ICP"
), class = "factor"), value = c(0.044, 0.1316, 0.0101, 0.0114,
80.13, 15.42)), .Names = c("Site", "Time", "DateCorrectFmt",
"variable", "value"), row.names = c(1L, 2L, 6L, 8L, 11L, 14L), class =
"data.frame")

WQFunc <-  function(df){
      within(df, CalcFlag <- ifelse(variable =="CaD_ICP",
(dataqualifier <- c("Y", "Q", "","A")[findInterval(value,c(-Inf,
0.027, 0.1, 100, Inf))]), ""))
}

WQ <- WQFunc(WaterData)

print(WaterData)
print(WQ)

On Wed, Dec 7, 2011 at 5:01 PM, Steve E. <[hidden email]> wrote:

> Thanks to everyone for continued assistance with this problem.  I realize
> that I had not included enough information, hopefully I have done so here.
> I attached a dput output of a sample of the data titled 'WaterData' (and str
> output below).  Below are dput outputs of the function I am trying to get
> working and the resulting array when I run it.  Unfortunately, Michael,
> changing 'with' to 'within' did not solve the problem, as running the
> function in that case produced no discernible output or result.  What I
> meant by the function now producing an array of values (though the result I
> am looking for) that are not attached to the data frame, is that they show
> up separately in a result window (in a similar format to what you get from
> dput() and are not at all associated with the data frame).  Again, thanks so
> much!
>
>> dput(WQFunc)
> function (dataframe)
> {
>    dataframe$CalcFlag <- with(dataframe, ifelse(variable ==
>        "CaD_ICP", (dataqualifier <- c("Y", "Q", "",
> "A")[findInterval(dataframe$value,
>        c(-Inf, 0.027, 0.1, 100, Inf))]), ""))
> }
>
>> str(WaterData)
> 'data.frame':   126 obs. of  5 variables:
>  $ Site          : Factor w/ 6 levels "BV","CB","KP",..: 3 3 3 3 3 3 3 3 3 3
> ...
>  $ Time          : Factor w/ 84 levels "0:00:00","0:00:52",..: 1 1 1 1 2 5
> 16 16 19 20 ...
>  $ DateCorrectFmt: Factor w/ 9 levels "2010-08-17","2010-08-21",..: 4 8 1 3
> 8 5 5 8 8 8 ...
>  $ variable      : Factor w/ 3 levels "CaD_ICP","NaD_ICP",..: 1 1 1 1 1 1 1
> 1 1 1 ...
>  $ value         : num  0.044 0.1316 0.0101 0.0114 80.13 ...
>
> Below is the output I get if if I run the WQFunc as:
> flagged <- WQFunc(WaterData)
>
>> dput(Flagged)
> c("Q", "", "Y", "Y", "", "", "", "", "", "", "", "", "", "",
> "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
> "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
> "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
> "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
> "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
> "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
> "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", ""
> )
>>
>
>
> Again, though, 'Flagged' is an array of those values in a output window but
> are not 'attached' to WaterData.
>
> --
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

[Steve E.]

Michael (and others) - Right, 'within' did work, I had placed it in the wrong location previously, which your example code made clear.  I wrapped several of these functions within a function to address all the desired flags in a single pass (probably horribly inefficient but it works).  Thanks again for your most generous assistance.  Steve