index ops added to DataFrame

polars/src/frame/upstream_traits.rs

@@ -0,0 +1,61 @@
+use crate::prelude::*;
+use std::iter::FromIterator;
+use std::ops::{
+    Index, IndexMut, Range, RangeFrom, RangeFull, RangeInclusive, RangeTo, RangeToInclusive,
+};
+
+impl FromIterator<Series> for DataFrame {
+    /// # Panics
+    ///
+    /// Panics if Series have different lengths.
+    fn from_iter<T: IntoIterator<Item = Series>>(iter: T) -> Self {
+        let v = iter.into_iter().collect();
+        DataFrame::new(v).expect("could not create DataFrame from iterator")
+    }
+}
+
+impl Index<usize> for DataFrame {
+    type Output = Series;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self.columns[index]
+    }
+}
+
+/// Gives mutable access to a DataFrame.
+/// Warning: Use with care, if you modify the Series by replacing it with a different lengthed
+/// Series you've invalidated the DataFrame.
+impl IndexMut<usize> for DataFrame {
+    fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+        &mut self.columns[index]
+    }
+}
+
+macro_rules! impl_ranges {
+    ($range_type:ty) => {
+        impl Index<$range_type> for DataFrame {
+            type Output = [Series];
+
+            fn index(&self, index: $range_type) -> &Self::Output {
+                &self.columns[index]
+            }
+        }
+    };
+}
+
+impl_ranges!(Range<usize>);
+impl_ranges!(RangeInclusive<usize>);
+impl_ranges!(RangeFrom<usize>);
+impl_ranges!(RangeTo<usize>);
+impl_ranges!(RangeToInclusive<usize>);
+impl_ranges!(RangeFull);
+
+// we don't implement Borrow<str> or AsRef<str> as upstream crates may add impl of trait for usize.
+impl Index<&str> for DataFrame {
+    type Output = Series;
+
+    fn index(&self, index: &str) -> &Self::Output {
+        let idx = self.name_to_idx(index).unwrap();
+        &self.columns[idx]
+    }
+}