help wrapping findInterval into a function

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

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