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rlistunique

Extract unique value from a list of data frames into new data frame with indexing

I have a list of data frames of the following structure: 

cust_num   V2   V3 ...

Each data frame present a group of customers, where cust_num can appear more than once in a single data frame.

I want to extract the unique customers of each data frame and to insert them to a new data frame with index of the data frame (i.e., group) they came from.

Here is an example: 

# df1

cust_num   V2   V3 ...
   1 
   1
   2 

# df2

cust_num   V2   V3 ...
   4 
   4
   5

and I want my result to be: 

cust_num   group
     1       1
     2       1
     4       2
     5       2

I tried to use for loop, but I got troubles inserting the data into new data frame and create the group index: 

for (i in 1:length(df_list)) {
          x <- unique(df_list[[i]][1])
          new_df <- rbind(x)
}

Thank you in advance

Solution

  • If dat is your list of data frames: 

    do.call(rbind,lapply(seq_along(dat), function(x) data.frame(cust_num=unique(dat[[x]][,1]),group=x)))