trxcllnt commented on issue #31458:
URL: https://github.com/apache/arrow/issues/31458#issuecomment-1494961959
@feefladder we have a few rudimentary column-wise `select()` and `assign()`
routines on Table (and RecordBatch and Schema). This is written by hand so
apologies if it doesn't compile, but here's how I'd implement something like
that:
```typescript
import {DataType, Vector, makeTable} from "apache-arrow"
function* filter<T extends DataType>(vec: Vector<T>, pred: (x: T['TValue'])
=> boolean) {
for (const val of vec) { yield pred(val); }
}
const src = makeTable({ name: ["Alice", "Bob"], otherColumn: [1, 2] });
const dst = src.assign(makeTable({
name: filter(src.getChild("name"), (x) => x === "bob")
}));
```
We explicitly wanted to enable using iterators like this, as there's lots of
existing JS Iterator/AsyncIterator algorithm libraries (and even a [language
proposal](https://github.com/tc39/proposal-iterator-helpers)!). So if instead
you can use an iterator library like [IxJS](https://github.com/reactiveX/ixjs):
```typescript
import {makeTable} from "apache-arrow";
import {filter} from "ix/iterable/operators/filter";
const src = makeTable({ name: ["Alice", "Bob"], otherColumn: [1, 2] });
const dst = src.assign(makeTable({
name: filter((x) => x === "bob")(src.getChild("name"))
}));
```
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