Nota

This guide is written for Python 3, however, these instructionsshould work fine on Python 2.7—if you are still using it, for some reason.

Make sure you’ve got Python & pip¶

Before you go any further, make sure you have Python and that it’s availablefrom your command line. You can check this by simply running:

$ python --version

You should get some output like3.6.2. If you do not have Python, pleaseinstall the latest 3.x version frompython.org or refer to theInstalling Python section of this guide.

>>>pythonTraceback (most recent call last):  File"<stdin>", line1, in<module>NameError:name 'python' is not defined

Additionally, you’ll need to make sure you havepip available. You cancheck this by running:

$ pip --version

If you installed Python from source, with an installer frompython.org, orviaHomebrew you should already have pip. If you’re on Linux and installedusing your OS package manager, you may have toinstall pip separately.

Installing Pipenv¶

Pipenv is a dependency manager for Python projects. If you’re familiarwith Node.js’npm or Ruby’sbundler, it is similar in spirit to thosetools. Whilepip can install Python packages, Pipenv is recommended asit’s a higher-level tool that simplifies dependency management for common usecases.

Usepip to install Pipenv:

$ pip install --user pipenv

Installing packages for your project¶

Pipenv manages dependencies on a per-project basis. To install packages,change into your project’s directory (or just an empty directory for thistutorial) and run:

$cd project_folder$ pipenv install requests

Pipenv will install the excellentRequests library and create aPipfilefor you in your project’s directory. ThePipfile is used to track whichdependencies your project needs in case you need to re-install them, such aswhen you share your project with others. You should get output similar to this(although the exact paths shown will vary):

Creating a Pipfile for this project...Creating a virtualenv for this project...Using base prefix '/usr/local/Cellar/python3/3.6.2/Frameworks/Python.framework/Versions/3.6'New python executable in ~/.local/share/virtualenvs/tmp-agwWamBd/bin/python3.6Also creating executable in ~/.local/share/virtualenvs/tmp-agwWamBd/bin/pythonInstalling setuptools, pip, wheel...done.Virtualenv location: ~/.local/share/virtualenvs/tmp-agwWamBdInstalling requests...Collecting requests  Using cached requests-2.18.4-py2.py3-none-any.whlCollecting idna<2.7,>=2.5 (from requests)  Using cached idna-2.6-py2.py3-none-any.whlCollecting urllib3<1.23,>=1.21.1 (from requests)  Using cached urllib3-1.22-py2.py3-none-any.whlCollecting chardet<3.1.0,>=3.0.2 (from requests)  Using cached chardet-3.0.4-py2.py3-none-any.whlCollecting certifi>=2017.4.17 (from requests)  Using cached certifi-2017.7.27.1-py2.py3-none-any.whlInstalling collected packages: idna, urllib3, chardet, certifi, requestsSuccessfully installed certifi-2017.7.27.1 chardet-3.0.4 idna-2.6 requests-2.18.4 urllib3-1.22Adding requests to Pipfile's [packages]...P.S. You have excellent taste! ✨ 🍰 ✨

Using installed packages¶

Now that Requests is installed you can create a simplemain.py file touse it:

importrequestsresponse=requests.get('https://httpbin.org/ip')print('Your IP is {0}'.format(response.json()['origin']))

Then you can run this script usingpipenvrun:

$ pipenv run python main.py

You should get output similar to this:

Your IP is 8.8.8.8

Using$pipenvrun ensures that your installed packages are available toyour script. It’s also possible to spawn a new shell that ensures all commandshave access to your installed packages with$pipenvshell.

Next steps¶

Congratulations, you now know how to install and use Python packages! ✨ 🍰 ✨

Uso¶

1. Criar um ambiente virtual para um projeto:

$cd project_folder$ virtualenv venv

virtualenvvenv will create a folder in the current directory which willcontain the Python executable files, and a copy of thepip library which youcan use to install other packages. The name of the virtual environment (in thiscase, it wasvenv) can be anything; omitting the name will place the filesin the current directory instead.

This creates a copy of Python in whichever directory you ran the command in,placing it in a folder namedvenv.

Vocẽ também poderá usar qualquer versão do interpretador Python se preferir (comopython2.7).

$ virtualenv -p /usr/bin/python2.7 venv

ou definir o interpretador global com uma variável de ambiente no arquivo~/.bashrc:

$exportVIRTUALENVWRAPPER_PYTHON=/usr/bin/python2.7

2. Para começar a usar o ambiente virtual, ele precisa primeiro ser ativado:

$source venv/bin/activate

The name of the current virtual environment will now appear on the left ofthe prompt (e.g.(venv)Your-Computer:project_folderUserName$) to let you knowthat it’s active. From now on, any package that you install using pip will beplaced in thevenv folder, isolated from the global Python installation.

For Windows, the same command mentioned in step 1 can be used to create a virtual environment. However, activating the environment requires a slightly different command.

Assuming that you are in your project directory:

C:\Users\SomeUser\project_folder> venv\Scripts\activate

Install packages using thepip command:

$ pip install requests

3. Se você já tiver terminado de trabalhar no ambiente virtual no momento, você pode desativá-lo:

$ deactivate

Isso faz com que você volte a versão padrão do interpretador Python do sistema e todas as suas bibliotecas.

To delete a virtual environment, just delete its folder. (In this case,it would berm-rfvenv.)

After a while, though, you might end up with a lot of virtual environmentslittered across your system, and it’s possible you’ll forget their names orwhere they were placed.

Other Notes¶

Runningvirtualenv with the option--no-site-packages will notinclude the packages that are installed globally. This can be usefulfor keeping the package list clean in case it needs to be accessed later.[This is the default behavior forvirtualenv 1.7 and later.]

In order to keep your environment consistent, it’s a good idea to “freeze”the current state of the environment packages. To do this, run:

$ pip freeze > requirements.txt

This will create arequirements.txt file, which contains a simplelist of all the packages in the current environment, and their respectiveversions. You can see the list of installed packages without the requirementsformat usingpiplist. Later it will be easier for a different developer(or you, if you need to re-create the environment) to install the same packagesusing the same versions:

$ pip install -r requirements.txt

This can help ensure consistency across installations, across deployments,and across developers.

Lastly, remember to exclude the virtual environment folder from sourcecontrol by adding it to the ignore list (seeVersion Control Ignores).

virtualenvwrapper¶

virtualenvwrapperprovides a set of commands which makes working with virtual environments muchmore pleasant. It also places all your virtual environments in one place.

To install (make surevirtualenv is already installed):

$ pip install virtualenvwrapper$exportWORKON_HOME=~/Envs$source /usr/local/bin/virtualenvwrapper.sh

(Full virtualenvwrapper install instructions.)

For Windows, you can use thevirtualenvwrapper-win.

To install (make surevirtualenv is already installed):

$ pip install virtualenvwrapper-win

In Windows, the default path for WORKON_HOME is %USERPROFILE%\Envs

$ mkvirtualenv project_folder

$ workon project_folder

$ mkproject project_folder

$ deactivate

$ rmvirtualenv venv

virtualenv-burrito¶

Withvirtualenv-burrito, youcan have a working virtualenv + virtualenvwrapper environment in a single command.

direnv¶

When youcd into a directory containing a.env,direnvautomagically activates the environment.

Install it on Mac OS X usingbrew:

$ brew install direnv

On Linux follow the instructions atdirenv.net