jsontableschema-pandas 0.4.0

Generate Pandas data frames, load and extract data, based on JSON Table Schema descriptors.

# jsontableschema-pandas

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Generate and load Pandas data frames based on JSON Table Schema descriptors.

> Version `v0.2` contains breaking changes:
- removed `Storage(prefix=)` argument (was a stub)
- renamed `Storage(tables=)` to `Storage(dataframes=)`
- renamed `Storage.tables` to `Storage.buckets`
- changed `Storage.read` to read into memory
- added `Storage.iter` to yield row by row

## Getting Started

### Installation

```
$ pip install datapackage
$ pip install jsontableschema-pandas
```

### Example

You can easily load resources from a data package as Pandas data frames by simply using `datapackage.push_datapackage` function:

```python
>>> import datapackage

>>> data_url = 'http://data.okfn.org/data/core/country-list/datapackage.json'
>>> storage = datapackage.push_datapackage(data_url, 'pandas')

>>> storage.buckets
['data___data']

>>> type(storage['data___data'])
<class 'pandas.core.frame.DataFrame'>

>>> storage['data___data'].head()
Name Code
0 Afghanistan AF
1 Åland Islands AX
2 Albania AL
3 Algeria DZ
4 American Samoa AS
```

Also it is possible to pull your existing data frame into a data package:

```python
>>> datapackage.pull_datapackage('/tmp/datapackage.json', 'country_list', 'pandas', tables={
... 'data': storage['data___data'],
... })
Storage
```

### Storage

Package implements [Tabular Storage](https://github.com/frictionlessdata/jsontableschema-py#storage) interface.

We can get storage this way:

```python
>>> from jsontableschema_pandas import Storage

>>> storage = Storage()
```

Storage works as a container for Pandas data frames. You can define new data frame inside storage using `storage.create` method:

```python
>>> storage.create('data', {
... 'primaryKey': 'id',
... 'fields': [
... {'name': 'id', 'type': 'integer'},
... {'name': 'comment', 'type': 'string'},
... ]
... })

>>> storage.buckets
['data']

>>> storage['data'].shape
(0, 0)
```

Use `storage.write` to populate data frame with data:

```python
>>> storage.write('data', [(1, 'a'), (2, 'b')])

>>> storage['data']
id comment
1 a
2 b
```

Also you can use [tabulator](https://github.com/frictionlessdata/tabulator-py) to populate data frame from external data file:

```python
>>> import tabulator

>>> with tabulator.Stream('data/comments.csv', headers=1) as stream:
... storage.write('data', stream)

>>> storage['data']
id comment
1 a
2 b
1 good
```

As you see, subsequent writes simply appends new data on top of existing ones.

## API Reference

### Snapshot

https://github.com/frictionlessdata/jsontableschema-py#snapshot

### Detailed

- [Docstrings](https://github.com/frictionlessdata/jsontableschema-py/tree/master/jsontableschema/storage.py)
- [Changelog](https://github.com/frictionlessdata/jsontableschema-pandas-py/commits/master)

## Contributing

Please read the contribution guideline:

[How to Contribute](CONTRIBUTING.md)

Thanks!