Pandas: joining specific columns of one data frame to another

Question

I have 2 following data frames in pandas:

movies

+---+------------------------------+--------------+-----------+
|   | movie title                  | genre        | tconst    |
+---+------------------------------+--------------+-----------+
| 0 | Edison Kinetoscopic Record   | Documentary  | tt0000008 |
+---+------------------------------+--------------+-----------+
| 1 | La sortie des usines Lumière | Documentary  | tt0000010 |
+---+------------------------------+--------------+-----------+
| 2 | The Arrival of a Train       | Documentary  | tt0000012 |
+---+------------------------------+--------------+-----------+
| 3 | The Oxford and Cambridge     | NaN          | tt0000025 |
+---+------------------------------+--------------+-----------+
| 4 | Le manoir du diable          | Short|Horror | tt0000091 |
+---+------------------------------+--------------+-----------+

and crew

+---+-----------+-----------+---------+------+
|   | tconst    | directors | writers | year |
+---+-----------+-----------+---------+------+
| 0 | tt0000001 | nm0005690 | \N      | 2001 |
+---+-----------+-----------+---------+------+
| 1 | tt0000002 | nm0721526 | \N      | 2002 |
+---+-----------+-----------+---------+------+
| 2 | tt0000003 | nm0721526 | \N      | 2003 |
+---+-----------+-----------+---------+------+
| 3 | tt0000004 | nm0721526 | \N      | 2004 |
+---+-----------+-----------+---------+------+
| 4 | tt0000005 | nm0005690 | \N      | 2005 |
+---+-----------+-----------+---------+------+

How do I create a new data frame where I join directors and year columns only to movies data frame (using tconst column) ?

Answer 1

Try:

pd.merge(movies, crew[["tconst", "directors", "year"]], on="tconst", how="left")

the on parameter tells the function that you want to merge on the key tconst, the how parameter tells the function how you want to deal with rows that aren't intersections (shared) between the two DataFrames.