Convert tab separated values to ASCII table

Question

What is the most efficient way to convert tab separated data such as this:

a   b   c   d   cat
NULL    NULL    NULL    NULL    NULL
NULL    NULL    NULL    d   d
NULL    NULL    c   NULL    c
NULL    NULL    c   d   c; d
NULL    b   NULL    NULL    b
NULL    b   NULL    d   b; d
NULL    b   c   NULL    b; c
NULL    b   c   d   b; c; d
a   NULL    NULL    NULL    a
a   NULL    NULL    d   a; d
a   NULL    c   NULL    a; c
a   NULL    c   d   a; c; d
a   b   NULL    NULL    a; b
a   b   NULL    d   a; b; d
a   b   c   NULL    a; b; c
a   b   c   d   a; b; c; d

Something close to this:

a    | b    | c    | d    | cat
-----+------+------+------+-----------
NULL | NULL | NULL | NULL | NULL
NULL | NULL | NULL | d    | d
NULL | NULL | c    | NULL | c
NULL | NULL | c    | d    | c; d
NULL | b    | NULL | NULL | b
NULL | b    | NULL | d    | b; d
NULL | b    | c    | NULL | b; c
NULL | b    | c    | d    | b; c; d
a    | NULL | NULL | NULL | a
a    | NULL | NULL | d    | a; d
a    | NULL | c    | NULL | a; c
a    | NULL | c    | d    | a; c; d
a    | b    | NULL | NULL | a; b
a    | b    | NULL | d    | a; b; d
a    | b    | c    | NULL | a; b; c
a    | b    | c    | d    | a; b; c; d

Currently I use Notepad++ as follows:

1. Convert tabs to spaces
2. Align the data manually
3. Use column mode to insert the pipes

The second step is the most tedious one and I would rather have at least this part automated.

Note: I use a browser when working and sometimes I have a text editor open alongside. The efficient solution is the one that requires least amount of effort. I can use:

• Notepad++
• Generic text editor with regexp find/replace support
• JavaScript typed inside browser console
• Online web service
• PHP on command line (php -a)

Answer 1

How can I convert tab separated values to an ASCII table?

I use Text Tables Generator for this kind of task.

I pasted your data on that page and it created the following table:

+------+------+------+------+------------+
| a    | b    | c    | d    | cat        |
+------+------+------+------+------------+
| NULL | NULL | NULL | NULL | NULL       |
+------+------+------+------+------------+
| NULL | NULL | NULL | d    | d          |
+------+------+------+------+------------+
| NULL | NULL | c    | NULL | c          |
+------+------+------+------+------------+
| NULL | NULL | c    | d    | c; d       |
+------+------+------+------+------------+
| NULL | b    | NULL | NULL | b          |
+------+------+------+------+------------+
| NULL | b    | NULL | d    | b; d       |
+------+------+------+------+------------+
| NULL | b    | c    | NULL | b; c       |
+------+------+------+------+------------+
| NULL | b    | c    | d    | b; c; d    |
+------+------+------+------+------------+
| a    | NULL | NULL | NULL | a          |
+------+------+------+------+------------+
| a    | NULL | NULL | d    | a; d       |
+------+------+------+------+------------+
| a    | NULL | c    | NULL | a; c       |
+------+------+------+------+------------+
| a    | NULL | c    | d    | a; c; d    |
+------+------+------+------+------------+
| a    | b    | NULL | NULL | a; b       |
+------+------+------+------+------------+
| a    | b    | NULL | d    | a; b; d    |
+------+------+------+------+------------+
| a    | b    | c    | NULL | a; b; c    |
+------+------+------+------+------------+
| a    | b    | c    | d    | a; b; c; d |
+------+------+------+------+------------+

You can then copy this output (the generator has done most of the hard work), paste into notepad++ and clean up as appropriate.

Answer 2

If you need a command-line solution, you can also use pandoc with the pandoc-placetable filter.

Place your table in foo.txt and execute:

pandoc-placetable --file=foo.txt --delimiter="\t" --header | pandoc -f json -t markdown-simple_tables-multiline_tables -o output.md

Which results in the following output.md:

| a    | b    | c    | d    | cat        |
|------|------|------|------|------------|
| NULL | NULL | NULL | NULL | NULL       |
| NULL | NULL | NULL | d    | d          |
| NULL | NULL | c    | NULL | c          |
| NULL | NULL | c    | d    | c; d       |
| NULL | b    | NULL | NULL | b          |
| NULL | b    | NULL | d    | b; d       |
| NULL | b    | c    | NULL | b; c       |
| NULL | b    | c    | d    | b; c; d    |
| a    | NULL | NULL | NULL | a          |
| a    | NULL | NULL | d    | a; d       |
| a    | NULL | c    | NULL | a; c       |
| a    | NULL | c    | d    | a; c; d    |
| a    | b    | NULL | NULL | a; b       |
| a    | b    | NULL | d    | a; b; d    |
| a    | b    | c    | NULL | a; b; c    |
| a    | b    | c    | d    | a; b; c; d |

To read from STDIN, leave out the --file argument. To print to STDOUT, leave out the -o argument.

Answer 3

ruslan’s idea of using the Unix/Linux column command is a good one, but the command line given in their answer doesn’t quite work. First of all, column doesn’t recognize \t (or \\t) on the command line as a tab.  If you have bash, you can do

column -t -s$'\t' foo.txt

Otherwise, you can do

column -t -s"$(printf '\t')" foo.txt

But even that doesn’t answer the question.  You can get the vertical bars by doing

column -t -s$'\t' -o' | ' foo.txt

which produces output like

a    | b    | c    | d    | cat
NULL | NULL | NULL | NULL | NULL
NULL | NULL | NULL | d    | d
NULL | NULL | c    | NULL | c
NULL | NULL | c    | d    | c; d
NULL | b    | NULL | NULL | b
NULL | b    | NULL | d    | b; d
NULL | b    | c    | NULL | b; c
NULL | b    | c    | d    | b; c; d
a    | NULL | NULL | NULL | a
a    | NULL | NULL | d    | a; d
a    | NULL | c    | NULL | a; c
a    | NULL | c    | d    | a; c; d
a    | b    | NULL | NULL | a; b
a    | b    | NULL | d    | a; b; d
a    | b    | c    | NULL | a; b; c
a    | b    | c    | d    | a; b; c; d

Adding the dash line after the header manually isn’t so tedious.

---

If you don’t have access to a full Unix/Linux system, you can use Cygwin or one of the other Unix-likes for this.