# Hail now detects multiallelics on VCF import

**URL:** <https://discuss.hail.is/t/hail-now-detects-multiallelics-on-vcf-import/180>\
**Category:** Updates\
**Created:** [April 6, 2017, 4:23pm UTC](https://discuss.hail.is/t/hail-now-detects-multiallelics-on-vcf-import/180 "2017-04-06T16:23:45Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![tpoterba](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/tpoterba/32/61_2.png) [@tpoterba](https://discuss.hail.is/u/tpoterba)\
**Post date:** [April 6, 2017, 4:23pm UTC](https://discuss.hail.is/t/hail-now-detects-multiallelics-on-vcf-import/180/1 "2017-04-06T16:23:46Z")

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If your VCF is entirely biallelic, you’ll no longer need to call `split_multi` or `filter_multi` before using biallelic-only functions.

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**Author:** ![enriquea](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/enriquea/32/237_2.png) [@enriquea](https://discuss.hail.is/u/enriquea)\
**Post date:** [March 20, 2018, 3:56pm UTC](https://discuss.hail.is/t/hail-now-detects-multiallelics-on-vcf-import/180/2 "2018-03-20T15:56:59Z")

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Hi @tpoterba,

Migrating now to Hail 0.2, I don’t see a function such as filter\_multi()…How can I get my dataset with only bi-allelic variants?

Thanks

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<div class="post-metadata">

**Author:** ![tpoterba](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/tpoterba/32/61_2.png) [@tpoterba](https://discuss.hail.is/u/tpoterba)\
**Post date:** [March 20, 2018, 5:27pm UTC](https://discuss.hail.is/t/hail-now-detects-multiallelics-on-vcf-import/180/3 "2018-03-20T17:27:45Z")

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just use `filter_rows`:

```python
mt = mt.filter_rows(hl.len(mt.alleles) == 2)
```

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**Author:** ![tpoterba](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/tpoterba/32/61_2.png) [@tpoterba](https://discuss.hail.is/u/tpoterba)\
**Post date:** [March 20, 2018, 5:28pm UTC](https://discuss.hail.is/t/hail-now-detects-multiallelics-on-vcf-import/180/4 "2018-03-20T17:28:25Z")

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in 0.2, we no longer store information about whether the dataset is split. Instead, methods that don’t support multiallelics will error if they encounter one.

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**Author:** ![enriquea](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/enriquea/32/237_2.png) [@enriquea](https://discuss.hail.is/u/enriquea)\
**Post date:** [March 20, 2018, 5:45pm UTC](https://discuss.hail.is/t/hail-now-detects-multiallelics-on-vcf-import/180/5 "2018-03-20T17:45:58Z")

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Many thanks, @tpoterba !!!