Linear Model "NA" Value Test

if("fit$coef[[2]]" == "NA") {.cw = 1}

Hello,

I am deriving near real-time liner relationships based on 5-min
precipitation data, sometimes the non-qced data result in a slope of  
NA.  I
am trying to read the coefficient (in this example x) to see if it  
is equal
to NA, if it is equal to NA assign it a value of 1.  I am having  
trouble
with the if statement not recognizing the coefficient or "NA" value  
in the
test.

Any thoughts, I supplied a really basic example below.

Thank you,
Doug

#####################
###### Example ######
#####################
x=c(1,1,1)
y=c(1,1,1)
fit <- lm(y~x) fit

Call:
lm(formula = y ~ x)
Coefficients:
(Intercept)            x
1           NA

coef <- coef(fit) fit$coef[[2]]
[1] NA
if("fit$coef[[2]]" == "NA") {.cw = 1}

-- 
---------------------------------
Douglas M. Hultstrand, MS
Senior Hydrometeorologist
Metstat, Inc. Windsor, Colorado
voice: 970.686.1253
email: dmhultst at metstat.com
web: http://www.metstat.com

On Sep 21, 2009, at 4:38 PM, Douglas M. Hultstrand wrote:

Hello,

I am deriving near real-time liner relationships based on 5-min
precipitation data, sometimes the non-qced data result in a slope  
of NA.  I
am trying to read the coefficient (in this example x) to see if it  
is equal
to NA, if it is equal to NA assign it a value of 1.  I am having  
trouble
with the if statement not recognizing the coefficient or "NA" value  
in the
test.

Any thoughts, I supplied a really basic example below.

Thank you,
Doug

#####################
###### Example ######
#####################
x=c(1,1,1)
y=c(1,1,1)
fit <- lm(y~x) fit

Call:
lm(formula = y ~ x)
Coefficients:
(Intercept)            x
1           NA

coef <- coef(fit) fit$coef[[2]]
[1] NA
if("fit$coef[[2]]" == "NA") {.cw = 1}

That would test for equality to the string composed of "N" and "A"  
but not for NA. (Nothing "equals" NA. )

?is.na

Hello,

I am deriving near real-time liner relationships based on 5-min
precipitation data, sometimes the non-qced data result in a
slope of NA. I am trying to read the coefficient (in this example x)
to see if it is equal to NA, if it is equal to NA assign it a value
of 1. I am having trouble with the if statement not recognizing the
coefficient or "NA" value in the test.

Any thoughts, I supplied a really basic example below.

Thank you,
Doug

#####################
###### Example ######
#####################
x=c(1,1,1)
y=c(1,1,1)
fit <- lm(y~x) fit

Call:
lm(formula = y ~ x)
Coefficients:
(Intercept)            x
1           NA

coef <- coef(fit) fit$coef[[2]]
[1] NA
if("fit$coef[[2]]" == "NA") {.cw = 1}