# Just when I thought I had the basic stuff mastered....
# This has been quite perplexing, thanks for any help


## Here's the example:

db1=data.frame(
    olditems=c('soup','','','','nuts'),
    prices=c(4.45, 3.25, 4.42, 2.25, 3.98))
db2=data.frame(
    newitems=c('stew','crackers','tofu','goatsmilk','peanuts'))

str(db1)    #factors and prices
str(db2)    #new names, but I want *only* the updates

is.na(db1$olditems)  #a little surprising that '' is not equal to NA
db1$olditems==''     #oh good, at least I can get to the blanks this way
db1$olditems[db1$olditems=='']  #wait, only one item is returned?
db1[db1$olditems=='',]  #somehow this works!

#how would I get the new item names into the old items column of db1??
# I was expecting that this would work:
#    db1$olditems[db1$olditems=='']=
#        db2$newitems[db1$olditems=='']

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