[R] NA preserved in logical call - I don't understand this behavior because NA is not equal to 0

[stephen sefick]

I am confused by the behavior of the below piece of code.  The NAs are
making it past the logical call ==0.  I am sure that I am missing
something.  I just don't understand this behavior.  Thanks for your
help in advance.


########code#######################################################
left <- (structure(list(measurment_num = c(2, 2.2, 2.4, 2.6, 2.8, 2.82,
3, NA, NA, NA), bankfull_depths_m = c(1.29, 1.28, 1.23, 0.18,
-0.05, 0, -0.09, NA, NA, NA)), .Names = c("measurment_num", "bankfull_depths_m"
), row.names = c(10L, 11L, 12L, 13L, 14L, 20L, 15L, 16L, 17L,
18L), class = "data.frame"))

if(sum(left[,"bankfull_depths_m"]==0, na.rm=TRUE) == 1){
left_min <- left[left[,"bankfull_depths_m"]==0, "measurment_num"]
}

left
##################################################################

-- 
Stephen Sefick
____________________________________
| Auburn University                                   |
| Department of Biological Sciences           |
| 331 Funchess Hall                                  |
| Auburn, Alabama                                   |
| 36849                                                    |
|___________________________________|
| sas0025 at auburn.edu                             |
| http://www.auburn.edu/~sas0025             |
|___________________________________|

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