jorgecarleitao commented on a change in pull request #9293:
URL: https://github.com/apache/arrow/pull/9293#discussion_r563148896
##########
File path: rust/arrow/src/array/array_primitive.rs
##########
@@ -94,6 +94,32 @@ impl<T: ArrowPrimitiveType> PrimitiveArray<T> {
let offset = i + self.offset();
unsafe { *self.raw_values.as_ptr().add(offset) }
}
+
+ /// Creates a PrimitiveArray based on an iterator of values without nulls
+ pub fn from_iter_values<I: IntoIterator<Item = T::Native>>(iter: I) ->
Self {
+ let iter = iter.into_iter();
+ let (_, data_len) = iter.size_hint();
+ let data_len = data_len.expect("Iterator must be sized"); // panic if
no upper bound.
+
+ let mut val_buf = MutableBuffer::new(
+ data_len * mem::size_of::<<T as ArrowPrimitiveType>::Native>(),
+ );
+
+ iter.for_each(|item| {
+ val_buf.push(item);
+ });
Review comment:
Yes, that is what I meant: it should now be possible to do
```rust
let values = vec![0i32, 1];
let values = values.iter().map(|x| x + 1);
let buffer: Buffer: values.collect();
```
wrt to the `len`: that is a good point that I have had not thought about. 👍
One option is to do what you wrote. Another could be (I haven't tried to
compile this, as `Fn` could become `FnMut`):
```
let mut count = 0;
let iter = iter.map(|x| {
count += 1;
x
});
```
I would probably have taken your idea, though :)
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