# Missing \['array\] when using map() method

**URL:** <https://discuss.huggingface.co/t/missing-array-when-using-map-method/26615>\
**Category:** Beginners\
**Created:** [November 24, 2022, 12:21am UTC](https://discuss.huggingface.co/t/missing-array-when-using-map-method/26615 "2022-11-24T00:21:22Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Peccatum](https://avatars.discourse-cdn.com/v4/letter/p/f17d59/32.png) [@Peccatum](https://discuss.huggingface.co/u/Peccatum)\
**Post date:** [November 24, 2022, 12:21am UTC](https://discuss.huggingface.co/t/missing-array-when-using-map-method/26615/1 "2022-11-24T00:21:22Z")

</div>

Hello every one. When I use map method to modify the data. Return a KeyError: ‘array’.  
But I’m sure my dataset include this column.

```auto
print(ds_train)
print(ds_train[1]['audio']['array'])

```

And the output is:

```auto
Dataset({
    features: ['audio', 'gender'],
    num_rows: 16960
})
tensor([-8.2690e-14, -7.3000e-13, 1.5195e-13, ..., 8.2001e-07,
         9.9102e-07, -3.9292e-07], device='cuda:0')

```

My code is:

```auto
feature_extractor = Wav2Vec2FeatureExtractor.from_pretrained("facebook/wav2vec2-base-960h")
def preprocess_function(examples):
    print(examples)
    audio_arrays = [x["array"] for x in examples["audio"]]
    inputs = feature_extractor(
        audio_arrays, sampling_rate=feature_extractor.sampling_rate, max_length=16000,
        truncation=True, padding=True, 
    )
    return inputs
ds_train = ds_train.map(preprocess_function, remove_columns="audio", batched=True)

```

I’m not sure what happend. Thank you in advance.

---

<div class="post-metadata">

**Author:** ![hfuser1](https://avatars.discourse-cdn.com/v4/letter/h/f04885/32.png) [@hfuser1](https://discuss.huggingface.co/u/hfuser1)\
**Post date:** [November 24, 2022, 8:44pm UTC](https://discuss.huggingface.co/t/missing-array-when-using-map-method/26615/2 "2022-11-24T20:44:28Z")

</div>

I’m seeing this behavior too. `array` is there when manually indexing into the dataset, but only `{'bytes': None, 'path': './data/xyz.mp3'}` inside of the map() callback function.

It only seems to happen if I have `dataset.set_format(type='torch')` - if I don’t call that before map(), then it works as expected.

---

<div class="post-metadata">

**Author:** ![Peccatum](https://avatars.discourse-cdn.com/v4/letter/p/f17d59/32.png) [@Peccatum](https://discuss.huggingface.co/u/Peccatum)\
**Post date:** [November 25, 2022, 3:37am UTC](https://discuss.huggingface.co/t/missing-array-when-using-map-method/26615/3 "2022-11-25T03:37:38Z")

</div>

That works! Thank you!