Fix references to old method

crates/polars-core/src/frame/mod.rs

@@ -1147,7 +1147,7 @@ impl DataFrame {
                 series = series.new_from_index(0, height);
             }
 
-            if series.len() == height || df.is_empty() {
+            if series.len() == height || df.get_columns().is_empty() {
                 df.add_column_by_search(series)?;
                 Ok(df)
             }
@@ -1220,7 +1220,7 @@ impl DataFrame {
             series = series.new_from_index(0, height);
         }
 
-        if series.len() == height || self.is_empty() {
+        if series.len() == height || self.columns.is_empty() {
             self.add_column_by_schema(series, schema)?;
             Ok(self)
         }

crates/polars-io/src/predicates.rs

@@ -25,7 +25,7 @@ pub fn apply_predicate(
     predicate: Option<&dyn PhysicalIoExpr>,
     parallel: bool,
 ) -> PolarsResult<()> {
-    if let (Some(predicate), false) = (&predicate, df.is_empty()) {
+    if let (Some(predicate), false) = (&predicate, df.get_columns().is_empty()) {
         let s = predicate.evaluate_io(df)?;
         let mask = s.bool().expect("filter predicates was not of type boolean");
 

py-polars/src/interop/numpy/to_numpy_df.rs

@@ -44,9 +44,7 @@ fn df_to_numpy(
     writable: bool,
     allow_copy: bool,
 ) -> PyResult<PyObject> {
-    // TODO: Use `is_empty` when fixed:
-    // https://github.com/pola-rs/polars/pull/16351
-    if df.height() == 0 {
+    if df.is_empty() {
         // Take this path to ensure a writable array.
         // This does not actually copy data for an empty DataFrame.
         return df_to_numpy_with_copy(py, df, order, true);
@@ -76,10 +74,7 @@ fn df_to_numpy(
 }
 
 fn try_df_to_numpy_view(py: Python, df: &DataFrame) -> Option<PyObject> {
-    if df.is_empty() {
-        return None;
-    }
-    let first = df.get_columns().first().unwrap().dtype();
+    let first = df.get_columns().first()?.dtype();
     // TODO: Support Datetime/Duration/Array types
     if !first.is_numeric() {
         return None;