I understood that by would take the intersection of names(x) and names(y),
names(x) being the column names of x and names(y), column names of y.
if x has 5 col and the col names of x are col1, col2... col5 and y has 3 col
and their names are col1, col2, col3, I thought that the merged data set will
have 3 col, namely col1, col2, col3 but all 5 col, i.e. col1, col2... col5 are
taken if nothing is specified for the by arg.
Cheers,
On Monday, June 1, 2015 4:32 PM, Michael Dewey <li...@dewey.myzen.co.uk>
wrote:
On 01/06/2015 14:46, carol white via R-help wrote:
> Hi,By default the merge function should take the intersection of column names
(if this is understood from by = intersect(names(x), names(y)),
Dear Carol
The by parameter specifies which columns are used to merge by. Did you
understand it to be which columns are retained in the result?
Just a hunch, and if not then you need to give us a toy example.
but it takes all columns. How to specify the intersection of column names?
> Thanks
> Carol
>
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>
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--
Michael
http://www.dewey.myzen.co.uk/home.html
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