On 10/22/2008 11:21 AM, Ivan Alves wrote:
Dear all,
I searched the mail archives and the R site and found no guidance
(tried "merge", "cbind" and terms like "coalesce" with no success).
There surely is a way to coalesce (like in SQL) columns in a
dataframe, right? For example, I would like to go from a dataframe
with two columns to one with only one as follows:
From
Name.x Name.y
nx1 ny1
nx2 NA
NA ny3
NA NA
...
To
Name
nx1
nx2
ny3
NA
...
where column Name.x is taken if there is a value, and if not then
column Name.y
Any help would be appreciated
I don't know of any special function to do that, but ifelse() can handle
it easily:
Name <- ifelse(is.na(Name.x), Name.y, Name.x)
(If those are columns of a dataframe named df, you'd prefix each column
name by df$, or do
within(df, Name <- ifelse(is.na(Name.x), Name.y, Name.x))
Duncan Murdoch
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