Question

I have a tab delimited file, in which the first 10 columns are always present and stay at same position, but after the 10th column, the number of columns can change. I want to retain the first 10 columns as is and concatenate the rest of the columns into one column separated by |.

Here is the sample data:

columns: col1 col2 … col 10 col11 col12 col13

Values: 1 2 … 10 11 12 13

Result:

Columns: col1 col2 … col10 col11|col12|col13

Values: 1 2 … 10 11 | 12 | 13

Answer 1

Take a look at ruby’s split method – it takes an optional limit parameter. Assuming your data is in a variable row for each line:

values = row.split("\t", 11)

Example (with the variable part starting at column 3 for brevity):

s = "1\t2\t3\t4" 
cols = s.split("\t", 3) 
# result: ["1", "2", "3\t4"] 

Then you can change the last element in place:

cols[2] = cols.last.gsub("\t", "|")
# cols is now: ["1", "2", "3|4"]