 | 2000-01-01 | 39.81 |
|   MSFT | 2000-02-01 | 36.35 |
|   MSFT | 2000-03-01 | 43.22 |
|   MSFT | 2000-04-01 | 28.37 |
|   MSFT | 2000-05-01 | 25.45 |
user&gt; (ds/head (ds/add-or-update-column stocks "id"
                                        (dtype/make-reader :int64
                                                           (ds/row-count stocks)
                                                           idx)))
test/data/stocks.csv [5 4]:

| symbol |       date | price | id |
|--------+------------+---