baeldung_miller.md

When it encounters data files with different category columns, miller is able to manage record heterogeneity.

For example, we’ll create two other files with differing columns:

$ cat A4.csv
A,B
1,2
$ cat C4.csv
A,B,C
7,9,2

Next, we merge them using unsparsify verb, that prints records with the union of field names over all input records:

$ mlr --csv unsparsify A4.csv C4.csv > out4.csv
$ cat out4.csv
A,B,C
1,2,
7,9,2