zeppelin/docs/interpreter/python.md

---
layout: page
title: "Python Interpreter"
description: "Python Interpreter"
group: interpreter
---
{% include JB/setup %}

# Python 2 & 3 Interpreter for Apache Zeppelin

<div id="toc"></div>

## Configuration
<table class="table-configuration">
  <tr>
    <th>Property</th>
    <th>Default</th>
    <th>Description</th>
  </tr>
  <tr>
    <td>zeppelin.python</td>
    <td>python</td>
    <td>Path of the already installed Python binary (could be python2 or python3).
    If python is not in your $PATH you can set the absolute directory (example : /usr/bin/python)
    </td>
  </tr>
  <tr>
    <td>zeppelin.python.maxResult</td>
    <td>1000</td>
    <td>Max number of dataframe rows to display.</td>
  </tr>
</table>

## Enabling Python Interpreter

In a notebook, to enable the **Python** interpreter, click on the **Gear** icon and select **Python**

## Using the Python Interpreter

In a paragraph, use **_%python_** to select the **Python** interpreter and then input all commands.

The interpreter can only work if you already have python installed (the interpreter doesn't bring it own python binaries).

To access the help, type **help()**

## Python modules
The interpreter can use all modules already installed (with pip, easy_install...)

## Using Zeppelin Dynamic Forms
You can leverage [Zeppelin Dynamic Form]({{BASE_PATH}}/manual/dynamicform.html) inside your Python code.

**Zeppelin Dynamic Form can only be used if py4j Python library is installed in your system. If not, you can install it with `pip install py4j`.**

Example : 

```python
%python
### Input form
print (z.input("f1","defaultValue"))

### Select form
print (z.select("f1",[("o1","1"),("o2","2")],"2"))

### Checkbox form
print("".join(z.checkbox("f3", [("o1","1"), ("o2","2")],["1"])))
```


## Zeppelin features not fully supported by the Python Interpreter

* Interrupt a paragraph execution (`cancel()` method) is currently only supported in Linux and MacOs. If interpreter runs in another operating system (for instance MS Windows) , interrupt a paragraph will close the whole interpreter. A JIRA ticket ([ZEPPELIN-893](https://issues.apache.org/jira/browse/ZEPPELIN-893)) is opened to implement this feature in a next release of the interpreter.
* Progression bar in webUI  (`getProgress()` method) is currently not implemented.
* Code-completion is currently not implemented.

## Matplotlib integration
 The python interpreter can display matplotlib graph with the function `z.show()`.
 You need to have matplotlib module installed and a XServer running to use this functionality !
 
 ```python
%python
import matplotlib.pyplot as plt
plt.figure()
(.. ..)
z.show(plt)
plt.close()
```
z.show function can take optional parameters to adapt graph width and height

 ```python
%python
z.show(plt, width='50px')
z.show(plt, height='150px')
```
<img class="img-responsive" src="../assets/themes/zeppelin/img/docs-img/pythonMatplotlib.png" />


## Pandas integration
Apache Zeppelin [Table Display System]({{BASE_PATH}}/displaysystem/basicdisplaysystem.html#table) provides built-in data visualization capabilities. Python interpreter leverages it to visualize Pandas DataFrames though similar `z.show()` API, same as with [Matplotlib integration](#matplotlib-integration).

Example:

```python
import pandas as pd
rates = pd.read_csv("bank.csv", sep=";")
z.show(rates)
```

## SQL over Pandas DataFrames

There is a convenience `%python.sql` interpreter that matches Apache Spark experience in Zeppelin and enables usage of SQL language to query [Pandas DataFrames](http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.html) and visualization of results though built-in [Table Display System]({{BASE_PATH}}/displaysystem/basicdisplaysystem.html#table).

 **Pre-requests**

  - Pandas `pip install pandas`
  - PandaSQL `pip install -U pandasql`

In case default binded interpreter is Python (first in the interpreter list, under the _Gear Icon_), you can just use it as `%sql` i.e

 - first paragraph

  ```python
import pandas as pd
rates = pd.read_csv("bank.csv", sep=";")
  ```

 - next paragraph

  ```sql
%sql
SELECT * FROM rates WHERE age < 40
  ```

Otherwise it can be referred to as `%python.sql`


## Technical description

For in-depth technical details on current implementation please refer to [python/README.md](https://github.com/apache/zeppelin/blob/master/python/README.md).