alamb commented on a change in pull request #1033:
URL: https://github.com/apache/arrow-rs/pull/1033#discussion_r769039949
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File path: arrow/src/datatypes/schema.rs
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@@ -87,6 +87,18 @@ impl Schema {
Self { fields, metadata }
}
+
+ /// Returns a new schema with only the specified columns in the new schema
+ /// This carries metadata from the parent schema over as well
+ pub fn project(&self, indices: impl IntoIterator<Item=usize>) ->
Result<Schema> {
+ let mut new_fields = vec![];
+ for i in indices {
+ let f = self.fields[i].clone();
+ new_fields.push(f);
+ }
Review comment:
I think the for loop thing is what one would write in other languages
like C/C++, Java, go ,etc :) It is certainly what I was writing when I started
learning rust.
Then I realized that a big part of how rust avoids bounds checks while still
being safe is by the use of the functional style (as in the compiler sets up
the bound for `indicies` correctly once in the `into_iter()` and then doesn't
need to do any checking on each iteration)
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