Hi Carl,
I'm not 100% sure what you're after, but I'm assuming you're looking for
something like:
dt[, .SD, .SDcols=names(dt) %like% "Call1"]
That's syntax you can use to select all columns of a data.table
containing "Call1".
--Mel.
On 3/10/2016 2:00 PM, carlsutton wrote:
Hi
I did search but did not see an answer.
I have a dt with 580 + columns. many of the columns will have variations of
a name to specifically identify them, ie, call23,Call111, doCall.now, etc.
Since I cannot recall the exact column names I have been resorting to df
<- data.frame(dt) and then
a <- grep("Call1", colnames(df))
colnames(df[a])
which then returns the columns names containing Call1.
If I try this with the data table ie, colnames(dt[a]) I get null.
Any suggestions? I am feeling rather ignorant converting a dt back to a
data frame and available memory may be a concern further down the road.
Carl Sutton
-----
Carl Sutton
--
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