How to show common functions between elements in one column of data frame in R

Question

If the data frame contains a column on the elements, their functions and the values ​​of their functions, how to show common functions between the elements in one column of the data frame?

This is the input dataframe.

df <- data.frame(group = c(rep(c('A', 'B', 'C'), 3)),
                                   feature = c('x','x','x','y','y','z','z','w','t'),
                                   value=c(1,2,1,3,2,1,2,2,3))

This is an example of the desired result that compares any two pairs A & B, A & C, B & C and a filter for common functions:

df_desired <- data.frame(group1 =c('A','A','B'), group2 = c('B','C','C'), shared_feature = c('x','x','x'), value1 = c(1, 1,2), value2 = c(1, 2,1))

Answer 1

You can try the following:

# Added stringsAsFactors=F argument
df <- data.frame(group = c(rep(c('A', 'B', 'C'), 3)),
                 feature = c('x','x','x','y','y','z','z','w','t'),
                 value=c(1,2,1,3,2,1,2,2,3),stringsAsFactors = F)

df_desired <- data.frame(group1 =c('A','A','B'), group2 = c('B','C','C'), shared_feature = c('x','x','x'), value1 = c(1, 1,2), value2 = c(1, 2,1))

# For rbindlist function
library(data.table)

# Keep only features that are available for every group
df_agg = aggregate(value ~ feature, data = df, FUN = length)
shared_feats = df_agg$feature[df_agg$value==length(unique(df$group))]
df = df[df$feature %in% shared_feats,]

# A function that takes a feat_df containing the values of one feature for each group,
# and converts it to our expected output.
create_comb_df <- function(feat_df)
{
  df2 = as.data.frame(t(combn(feat_df$group,2)))
  colnames(df2) = c('group1','group2')
  df2$feature = feat_df$feature[1]
  df2$value1 = feat_df$value[match(df2$group1,feat_df$group)]
  df2$value2 = feat_df$value[match(df2$group2,feat_df$group)]
  return(df2)
}

# Create final output
rbindlist(lapply(split(df,as.character(df$feature)),create_comb_df))

Conclusion:

   group1 group2 feature value1 value2
1:      A      B       x      1      2
2:      A      C       x      1      1
3:      B      C       x      2      1

---

Or, to get all the common features, replace

shared_feats = df_agg$feature[df_agg$value==length(unique(df$group))]

with

shared_feats = df_agg$feature[df_agg$value>1]

and results:

   group1 group2 feature value1 value2
1:      A      B       x      1      2
2:      A      C       x      1      1
3:      B      C       x      2      1
4:      A      B       y      3      2
5:      C      A       z      1      2

Hope this helps!