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Documentation update.
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.. _quickstart:
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==========
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Quickstart
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==========
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.. module:: tablib
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Eager to get started? This page gives a good introduction in how to get started with Tablib. This assumes you already have Tablib installed. If you do not, head over to the :ref:`Installation <install>` section.
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First, make sure that:
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* Tablib is :ref:`installed <install>`
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* Tablib is :ref:`up-to-date <updates>`
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Lets gets started with some simple use cases and examples.
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------------------
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Creating a Dataset
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------------------
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A :class:`Dataset <tablib.Dataset>` is nothing more than what its name implies—a set of data.
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Creating your own instance of the :class:`tablib.Dataset` object is simple. ::
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data = tablib.Dataset()
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You can now start filling this :class:`Dataset <tablib.Dataset>` object with data.
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.. admonition:: Example Context
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From here on out, if you see ``data``, assume that it's a fresh :class:`Dataset <tablib.Dataset>` object.
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-----------
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Adding Rows
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-----------
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Let's say you want to collect a simple list of names. ::
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# collection of names
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names = ['Kenneth Reitz', 'Bessie Monke']
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for name in names:
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# split name appropriately
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fname, lname = name.split()
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# add names to Dataset
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data.append([fname, lname])
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You can get a nice, Pythonic view of the dataset at any time with :class:`Dataset.dict`.
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>>> data.dict
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[('Kenneth', 'Reitz'), ('Bessie', 'Monke')]
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--------------
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Adding Headers
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--------------
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It's time enhance our :class:`Dataset` by giving our columns some titles. To do so, set :class:`Dataset.headers`. ::
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data.headers = ['First Name', 'Last Name']
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Let's view the data in YAML this time. ::
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>>> data.yaml
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- {First Name: Kenneth, Last Name: Reitz}
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- {First Name: Bessie, Last Name: Monke}
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--------------
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Adding Columns
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--------------
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Now that we have a basic :class:`Dataset` in place, let's add a column of **ages** to it. ::
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data.append(col=['Age', 22, 20])
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Let's view the data in CSV this time. ::
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>>> data.csv
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Last Name,First Name,Age
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Reitz,Kenneth,22
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Monke,Bessie,20
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It's that easy.
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------------------------
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Selecting Rows & Columns
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------------------------
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You can slice and dice your data, just like a standard Python list. ::
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>>> data[0]
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('Kenneth', 'Reitz', 22)
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If we had a set of data consisting of thousands of rows, it could be useful to get a list of values in a column.
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To do so, we access the :class:`Dataset` as if it were a standard Python dictionary. ::
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>>> data['First Name']
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['Kenneth', 'Bessie']
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Let's find the average age. ::
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>>> ages = data['Age']
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>>> float(sum(ages)) / len(ages)
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21.0
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-----------------------
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Removing Rows & Columns
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-----------------------
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data.insert('MI', )
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>>> del data['Row Name']
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Fucking easy.
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==============
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Advanced Usage
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==============
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And now for something completely different.
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---------------
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Dynamic Columns
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---------------
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.. versionadded:: 0.8.3
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Thanks to Josh Ourisman, Tablib now supports adding dynamic columns. A dynamic column is a single callable object (*ie.* a function).
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For now, this is only supported on :class:`Dataset` objects that have no defined :class:`headers <Dataset.headers>`.
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So, let's save our headers for later, then remove them. ::
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_headers = list(data.headers)
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data.headers = None
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We can now add a dynamic column to our :class:`Dataset` object. In this example, we have a function that generates a random grade for our students. ::
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import random
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def random_grade(row):
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"""Returns a random integer for entry."""
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return (random.randint(60,100)/100.0)
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data.append(col=[random_grade])
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Now add the headers back, with our new column. ::
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>>> data.headers = _headers + ['Random']
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Let's have a look at our data. ::
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>>> data.yaml
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- {Age: 22, First Name: Kenneth, Grade: 0.6, Last Name: Reitz}
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- {Age: 21, First Name: Bessie, Grade: 0.75, Last Name: Monke}
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Let's remove that column. ::
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>>> del data['Grade']
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When you add a dynamic column, the first argument that is passed in to the given callable is the current data row. You can use this to perform calculations against your data row.
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For example, we can use the data available in the row to guess the gender of a student. ::
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def guess_gender(row):
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"""Calculates gender of given student data row."""
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m_names = ('Kenneth', 'Mike', 'Yuri')
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f_names = ('Bessie', 'Samantha', 'Heather')
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name = row[0]
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if name in m_names:
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return 'Male'
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elif name in f_names:
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return 'Female'
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else:
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return 'Unknown'
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Adding this function to our dataset as a dynamic column would result in: ::
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>>> data.yaml
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- {Age: 22, First Name: Kenneth, Gender: Male, Last Name: Reitz}
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- {Age: 21, First Name: Bessie, Gender: Female, Last Name: Monke}
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.. _seperators:
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----------
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Seperators
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----------
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.. versionadded:: 0.8.2
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Now, go check out the :ref:`API Documentation <api>` or begin :ref:`Tablib Development <development>`.
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