Usage for Beginners

This section shows the intended usage of the ezdxf package. This is just a brief overview for new ezdxf users, follow the provided links for more detailed information.

First import the package:

import ezdxf

Loading DXF Files

ezdxf supports loading ASCII and binary DXF files from a file:

doc = ezdxf.readfile(filename)

or from a zip-file:

doc = ezdxf.readzip(zipfilename[, filename])

Which loads the DXF file filename from the zip-file zipfilename or the first DXF file in the zip-file if filename is absent.

It is also possible to read a DXF file from a stream by the ezdxf.read() function, but this is a more advanced feature, because this requires detection of the file encoding in advance.

This works well with DXF files from trusted sources like AutoCAD or BricsCAD, for loading DXF files with minor or major flaws look at the ezdxf.recover module.

See also

Documentation for ezdxf.readfile(), ezdxf.readzip() and ezdxf.read(), for more information about file management go to the Document Management section. For loading DXF files with structural errors look at the ezdxf.recover module.

Saving DXF Files

Save the DXF document with a new name:

doc.saveas('new_name.dxf')

or with the same name as loaded:

doc.save()

See also

Documentation for ezdxf.document.Drawing.save() and ezdxf.document.Drawing.saveas(), for more information about file management go to the Document Management section.

Create a New DXF File

Create new file for the latest supported DXF version:

doc = ezdxf.new()

Create a new DXF file for a specific DXF version, e.g for DXF R12:

doc = ezdxf.new('R12')

To setup some basic DXF resources use the setup argument:

doc = ezdxf.new(setup=True)

See also

Documentation for ezdxf.new(), for more information about file management go to the Document Management section.

Layouts and Blocks

Layouts are containers for DXF entities like LINE or CIRCLE. The most important layout is the modelspace labeled as “Model” in CAD applications which represents the “world” work space. Paperspace layouts represents plottable sheets which contains often the framing and the tile block of a drawing and VIEWPORT entities as scaled and clipped “windows” into the modelspace.

The modelspace is always present and can not be deleted. The active paperspace is also always present in a new DXF document but can be deleted, in that case another paperspace layout gets the new active paperspace, but you can not delete the last paperspace layout.

Getting the modelspace of a DXF document:

msp = doc.modelspace()

Getting a paperspace layout by the name as shown in the tab of a CAD application:

psp = doc.layout('Layout1')

A block is just another kind of entity space, which can be inserted multiple times into other layouts and blocks by the INSERT entity also called block references, this is a very powerful and important concept of the DXF format.

Getting a block layout by the block name:

blk = doc.blocks.get('NAME')

All these layouts have factory functions to create graphical DXF entities for their entity space, for more information about creating entities see section: Create new DXF Entities

Create New Blocks

The block definitions of a DXF document are managed by the BlocksSection object:

my_block = doc.blocks.new('MyBlock')

Query DXF Entities

As said in the Layouts and Blocks section, all graphical DXF entities are stored in layouts, all these layouts can be iterated and support the index operator e.g. layout[-1] returns the last entity.

The main difference between iteration and index access is, that iteration filters destroyed entities, but the the index operator returns also destroyed entities until these entities are purged by layout.purge() more about this topic in section: Delete Entities.

There are two advanced query methods: query() and groupby().

Get all lines of layer 'MyLayer':

lines = msp.query('LINE[layer=="MyLayer"]')

This returns an EntityQuery container, which also provides the same query() and groupby() methods.

Get all lines categorized by a DXF attribute like color:

all_lines_by_color = msp.query('LINE').groupby('color')
lines_with_color_1 = all_lines_by_color.get(1, [])

The groupby() method returns a regular Python dict with colors as key and a regular Python list of entities as values (not an EntityQuery container).

See also

For more information go to the Tutorial for getting data from DXF files

Examine DXF Entities

Each DXF entity has a dxf namespace attribute, which stores the named DXF attributes, some DXF attributes are only indirect available like the vertices in the LWPOLYLINE entity. More information about the DXF attributes of each entity can found in the documentation of the ezdxf.entities module.

Get some basic DXF attributes:

layer = entity.dxf.layer  # default is '0'
color = entity.dxf.color  # default is 256 = BYLAYER

Most DXF attributes have a default value, which will be returned if the DXF attribute is not present, for DXF attributes without a default value you can check in the attribute really exist:

entity.dxf.hasattr('true_color')

or use the get() method and a default value:

entity.dxf.get('true_color', 0)

Create New DXF Entities

The factory functions for creating new graphical DXF entities are located in the BaseLayout class. This means this factory function are available for all entity containers:

The usage is simple:

msp = doc.modelspace()
msp.add_line((0, 0), (1, 0), dxfattribs={'layer': 'MyLayer'})

A few important or required DXF attributes are explicit method arguments, most additional and optional DXF attributes are gives as a regular Python dict object. The supported DXF attributes can be found in the documentation of the ezdxf.entities module.

Warning

Do not instantiate DXF entities by yourself and add them to layouts, always use the provided factory function to create new graphical entities, this is the intended way to use ezdxf.

Create Block References

A block reference is just another DXF entity called INSERT, but the term “Block Reference” is a better choice and so the Insert entity is created by the factory function: add_blockref():

msp.add_blockref('MyBlock')

See also

See Tutorial for Blocks for more advanced features like using Attrib entities.

Create New Layers

A layer is not an entity container, a layer is just another DXF attribute stored in the entity and this entity can inherit some properties from this Layer object. Layer objects are stored in the layer table which is available as attribute doc.layers.

You can create your own layers:

my_layer = doc.layer.new('MyLayer')

The layer object also controls the visibility of entities which references this layer, the on/off state of the layer is unfortunately stored as positive or negative color value which make the raw DXF attribute of layers useless, to change the color of a layer use the property Layer.color

my_layer.color = 1

To change the state of a layer use the provided methods of the Layer object, like on(), off(), freeze() or thaw():

my_layer.off()

See also

Layer Concept

Delete Entities

The safest way to delete entities is to delete the entity from the layout containing that entity:

line = msp.add_line((0, 0), (1, 0))
msp.delete_entity(line)

This removes the entity immediately from the layout and destroys the entity. The property is_alive returns False for a destroyed entity and all Python attributes are deleted, so line.dxf.color will raise an AttributeError exception, because line does not have a dxf attribute anymore.

The current version of ezdxf also supports also destruction of entities by calling method destroy() manually:

line.destroy()

Manually destroyed entities are not removed immediately from entities containers like Modelspace or EntityQuery, but iterating such a container will filter destroyed entities automatically, so a for e in msp: ... loop will never yield destroyed entities. The index operator and the len() function do not filter deleted entities, to avoid getting deleted entities call the purge() method of the container manually to remove deleted entities.

Further Information