Aliasing Columns Names in Map_Element () with Dataclass Fields about polars HOT 3 OPEN

Definitely don't do this in a Python function ;)

I think you just want this: unnest the struct column for simplicity, and then get the horizontal sum of everything except the first field (selectors¹ make that kind of column selection pretty easy - adjust as needed):

import polars.selectors as cs

Total_df.unnest("Market_Long").with_columns(
    Sum_Market_Long=pl.sum_horizontal(~cs.first())
)
# shape: (3, 5)
# ┌────────┬──────────┬──────────┬──────────┬─────────────────┐
# │ Ticker ┆ trader_a ┆ trader_b ┆ trader_c ┆ Sum_Market_Long │
# │ ---    ┆ ---      ┆ ---      ┆ ---      ┆ ---             │
# │ str    ┆ i64      ┆ i64      ┆ i64      ┆ i64             │
# ╞════════╪══════════╪══════════╪══════════╪═════════════════╡
# │ AAPL   ┆ 1        ┆ 2        ┆ 3        ┆ 6               │
# │ GOOGL  ┆ 1        ┆ 2        ┆ 3        ┆ 6               │
# │ MSFT   ┆ 1        ┆ 2        ┆ 3        ┆ 6               │
# └────────┴──────────┴──────────┴──────────┴─────────────────┘

from polars.

@alexander-beedie thanks for the reply...the selector works fine for a single nested dataclass , but for multidimensional dataclasses, there is more functionality required.Are there any other ways to access deep nested fields of mutlidimensional dataclasses?

from polars.

You should probably just use the Struct field access, optionally in conjunction with selectors, optionally unnesting to simplify the top-level (as shown). Once it's in Polars it's not a dataclass anymore (obviously ;) it is a Struct composed from the top-level fields of the input dataclass, so it's optimal to interact with it as such.

I'd suggest providing a more specific example that's closer to your real data and asking in the Discord channel for some suggestions (I can pick this up there if you do so) 👍

from polars.