Joining two data frames

The inner_join, outer_join, and left_join verbs perform the classic table join operations.

inner_join

This method performs the classic inner join operation. Rows on either side that are missing a corresponding row on the other side are dropped. Rows on either side that have multiple matches on the other side are duplicated.

from tabeline import DataFrame

df1 = DataFrame(x=[0, 1, 2, 3, 4], y=["a", "b", "c", "d", "e"])
df2 = DataFrame(x=[3, 2, -1, 1, 0], z=["a", "b", "z", "c", "d"])

df1.inner_join(df2)
# shape: (4, 3)
# ┌─────┬─────┬─────┐
# │ x   ┆ y   ┆ z   │
# │ --- ┆ --- ┆ --- │
# │ i64 ┆ str ┆ str │
# ╞═════╪═════╪═════╡
# │ 0   ┆ a   ┆ d   │
# ├╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌┤
# │ 1   ┆ b   ┆ c   │
# ├╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌┤
# │ 2   ┆ c   ┆ b   │
# ├╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌┤
# │ 3   ┆ d   ┆ a   │
# └─────┴─────┴─────┘

outer_join

This method performs the classic outer join (or full join) operation. Rows on either side that are missing a corresponding row on the other side are kept, filling the other side with nulls. Rows on either side that have multiple matches on the other side are duplicated.

from tabeline import DataFrame

df1 = DataFrame(x=[0, 1, 2, 3, 4], y=["a", "b", "c", "d", "e"])
df2 = DataFrame(x=[3, 2, -1, 1, 0], z=["a", "b", "z", "c", "d"])

df1.outer_join(df2)
# shape: (6, 3)
# ┌─────┬──────┬──────┐
# │ x   ┆ y    ┆ z    │
# │ --- ┆ ---  ┆ ---  │
# │ i64 ┆ str  ┆ str  │
# ╞═════╪══════╪══════╡
# │ -1  ┆ null ┆ z    │
# ├╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌┤
# │ 0   ┆ a    ┆ d    │
# ├╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌┤
# │ 1   ┆ b    ┆ c    │
# ├╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌┤
# │ 2   ┆ c    ┆ b    │
# ├╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌┤
# │ 3   ┆ d    ┆ a    │
# ├╌╌╌╌╌┼╌╌╌╌╌╌┼╌╌╌╌╌╌┤
# │ 4   ┆ e    ┆ null │
# └─────┴──────┴──────┘

left_join

This method performs the classic left join operation. Rows on the left side that are missing a corresponding row on the right side are kept, filling the right side with nulls. Rows on the right side that are missing a corresponding row on the left side are dropped. Rows on either side that have multiple matches on the other side are duplicated.

from tabeline import DataFrame

df1 = DataFrame(x=[0, 1, 2, 3, 4], y=["a", "b", "c", "d", "e"])
df2 = DataFrame(x=[3, 2, -1, 1, 0], z=["a", "b", "z", "c", "d"])

df1.left_join(df2)
# shape: (5, 3)
# ┌─────┬─────┬──────┐
# │ x   ┆ y   ┆ z    │
# │ --- ┆ --- ┆ ---  │
# │ i64 ┆ str ┆ str  │
# ╞═════╪═════╪══════╡
# │ 0   ┆ a   ┆ d    │
# ├╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌┤
# │ 1   ┆ b   ┆ c    │
# ├╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌┤
# │ 2   ┆ c   ┆ b    │
# ├╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌┤
# │ 3   ┆ d   ┆ a    │
# ├╌╌╌╌╌┼╌╌╌╌╌┼╌╌╌╌╌╌┤
# │ 4   ┆ e   ┆ null │
# └─────┴─────┴──────┘