Dries Dries - 1 year ago 67
R Question

R - list of identically named data frames: select on variable name

I have a list of data frames with the same structure (same variable-names, same number of observations). Something like



And I want to automate (mainly make the code independent of the number dataframes in the list) things like

DF$Condition = df.list[[1]]$Condition + df.list[[2]]$Condition


DF$Condition = all(df.list[[1]]$Condition, df.list[[2]]$Condition )

Answer Source

We can use Reduce with + after subsetting the 'condition' column

Reduce(`+`, lapply(df.list, `[`, 'condition'))

and for the second case

Reduce(function(...) identical(...), lapply(df.list, `[`, 'condition'))
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