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renkun-ken / rlist

A Toolbox for Non-Tabular Data Manipulation
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How to use variable for column name for expr in list.map()? #122

Closed mattbk closed 5 years ago

mattbk commented 5 years ago

I cam trying to pass an expr as a variable name and cannot figure it out.

# Example list
x <- list(p1 = list(type='A',score=list(c1=10,c2=8)),
       p2 = list(type='B',score=list(c1=9,c2=9)),
       p3 = list(type='B',score=list(c1=9,c2=7)))
# This works
list.map(x, type)
# This does not (it returns "type" three times)
sel <- "type"
list.map(x, sel)

Any suggestions?

mattbk commented 5 years ago

As soon as I wrote this, a solution popped into my head.

sel <- "type"
list.map(x, .[[sel]])