
I have a work around for this, but can someone explain why the first example does not work properly? I believed it worked in the previous version of R, by selecting just the rows=200525 and omitting the na's. I just upgraded to 2.13. I am also concern with the row numbers being different in the selections, should I be worried? FYI, I just selected the first few rows for demonstration, please do not worry that the number of rows shown are not equal. - Sarah

With na.omit around the column, but it is showing other values in the F.WW column other than 200525, along with NA.  I was hoping that this would omit all the NA's, and show all the rows that P$F.WW=200525. I believe it did with the previous version of R.
P[na.omit(P$F.WW)==200525, c(51, 52)]
          F.WW        R.WW
45      200525          NA
53          NA          NA
61      200534      200534
63      200608      200608
66      200522      200541
80          NA          NA
150     200521      200516
231     200530      200530

No na.omit, the F.WW=200525 seems to work, but lots of NA included. This is what is expected!! The row numbers are not the same as the above example, except the first row.
> P[P$F.WW==200525, c(51, 52)]
            F.WW     R.WW
45        200525          NA
NA            NA          NA
NA.1          NA          NA
NA.2          NA          NA
NA.3          NA          NA
57        200525      200526
65        200525          NA
67        200525          NA
70        200525      200525
NA.4          NA          NA
NA.5          NA          NA
86        200525          NA

Na.omit excludes the na's. This is what I want. The concern I have is why the row numbers do not match any of those shown in the examples above.
> na.omit(P[P$F.WW==200525, c(51, 52)])
        F.WW        R.WW
57    200525      200526
70    200525      200525
161   200525      200525
245   200525      200525
246   200525      200525
247   200525      200526
256   200525      200525
266   200525      200525
269   200525      200525
271   200525      200526
276   200525      200526
278   200525      200526

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