rowSums but keeping NA values

Question

I am pretty sure this is quite simple, but seem to have got stuck...I have two xts vectors that have been merged together, which contain numeric values and NAs.

I wo

Answer 1

Use logical indexing with [ and is.na(·) to localize the entries where both are NA and then replace them with NA.

Try this:

> mm[is.na(mm$dd1) & is.na(mm$dd2), "m"] <- NA
> mm
                 dd1        dd2        m
2013-08-02        NA         NA       NA
2013-08-03        NA         NA       NA
2013-08-04        NA         NA       NA
2013-08-05 1.2542692 -1.2542692 0.000000
2013-08-06        NA  1.3325804 1.332580
2013-08-07        NA  0.7726740 0.772674
2013-08-08 0.8158402 -0.8158402 0.000000
2013-08-09        NA  1.2292919 1.229292
2013-08-10        NA         NA       NA
2013-08-11        NA  0.9334900 0.933490