I want to pivot a table and aggregate a column into strings

Question

I have a select statement producing the following:

+---------+---------+------+
| Patient | Pattern | Rank |
+---------+---------+------+
| a       |      0  |    1 |
| a       |      1  |    2 |
| a       |      0  |    3 |
| a       |      0  |    4 |
| b       |       1 |    1 |
| b       |       1 |    2 |
| c       |       0 |    1 |
+---------+---------+------+

Desired output:

+---------+-----+---+---+---+
| Patient |  1  | 2 | 3 | 4 |
+---------+-----+---+---+---+
| a       |   0 | 1 | 0 | 0 |
| b       |   1 | 1 |   |   |
| c       |   0 |   |   |   |
+---------+-----+---+---+---+

Alternate desired output:

+---------+----------+
| Patient |  Pattern |
+---------+----------+
| a       |     0100 |
| b       |       11 |
| c       |        0 |
+---------+----------+

I know I need to do a pivot, but not much else. I'm using Oracle.

Here's my progress so far:

SELECT PATIENT_ID, LISTAGG(PATTERN, '') WITHIN GROUP (ORDER BY RANK ASC)

FROM

( the query above )

GROUP BY PATIENT_ID;