Rust Polars - Selecting columns after applying filter (on rows) of a DataFrame

Question

This used to be working until upgraded to latest Polars. The df Dataframe has more than 2 columns, CP and CP are 2 of them. The intent here is to select column CK and CP for rows that are greater than value 0.

let e11_filter = df
    .lazy()
    .filter(cols(["CK", "CP"]).gt(lit(0)))
    .collect()?;

The error is as below.

Error: ComputeError(ErrString("The predicate passed to 'LazyFrame.filter' expanded to multiple expressions:

    [(col(\"CK\")) > (0)],
    [(col(\"CP\")) > (0)],
This is ambiguous. Try to combine the predicates with the 'all_exprs' or 'any_exprs' expression.

Error originated just after this operation:
DF [\"W\", \"Dataset\", \"MD\", \"CK\"]; PROJECT */8 COLUMNS; SELECTION: \"None\""))

I found similar question, but it is Python version.

Answer 1

I'd make the call unambiguous by applying the "greater than 0" filter on each column explicitly and combining these resulting column filters with the and operation:

let e11_filter = df
    .lazy()
    .filter(col("CK").gt(lit(0)).and(col("CP").gt(lit(0))))
    .collect()
    .unwrap();

Rustexplorer.

---

Update: I got the all_exprs version Dogbert suggested to work, which is more in line with the answer of the Python version you've linked:

let e11_filter = df
    .lazy()
    .filter(all_exprs([cols(["CK", "CP"]).gt(lit(0))]))
    .collect()
    .unwrap();

Rustexplorer.