Summary
A Polyline object is a shape defined by one or more paths, in which a path is a series of connected segments.
Discussion
In many geoprocessing workflows, you may need to run a specific operation using coordinate and geometry information but don't necessarily want to go through the process of creating a new (temporary) feature class, populating the feature class with cursors, using the feature class, then deleting the temporary feature class. Geometry objects can be used instead for both input and output to make geoprocessing easier. Geometry objects can be created from scratch using Geometry, Multipoint, PointGeometry, Polygon, or Polyline classes.
During the creation of a geometry object, a simplification process is performed to make the geometry topologically consistent according to its geometry type. For instance, it rectifies polygons that may be selfintersecting, or contain incorrect ring orientations. Coordinates may move within the resolution of the geometry's spatial reference.
The following numeric operators can be used in place of geometry methods:
Geometry method  Numeric operator 

intersect  + 
union   
difference   
symmetricDifference  ^ 
For example, to union two geometry objects, g3 = g1  g2 is equivalent to g3 = g1.union(g2).
The + operator will use the geometry type (dimension) of the first geometry to determine the geometry type of the output.
Syntax
Polyline (inputs, {spatial_reference}, {has_z}, {has_m})
Parameter  Explanation  Data Type 
inputs  The coordinates used to create the object. The data type can be either Point or Array objects.  Object 
spatial_reference  The spatial reference of the new geometry. (The default value is None)  SpatialReference 
has_z  The Z state: True for geometry if Z is enabled and False if it is not. (The default value is False)  Boolean 
has_m  The M state: True for geometry if M is enabled and False if it is not. (The default value is False)  Boolean 
Properties
Property  Explanation  Data Type 
JSON (Read Only)  Returns an Esri JSON representation of the geometry as a string. Tip:The returned string can be converted to a dictionary using the json module's loads function.  String 
WKB (Read Only)  Returns the wellknown binary (WKB) representation for OGC geometry. It provides a portable representation of a geometry value as a contiguous stream of bytes.  Bytearray 
WKT (Read Only)  Returns the wellknown text (WKT) representation for OGC geometry. It provides a portable representation of a geometry value as a text string. Any true curves in the geometry will be densified into approximate curves in the WKT string.  String 
area (Read Only)  The area of a polygon feature. It is zero for all other feature types.  Double 
centroid (Read Only)  The true centroid if it is within or on the feature; otherwise, the label point is returned.  Point 
extent (Read and Write)  The extent of the geometry.  Extent 
firstPoint (Read Only)  The first coordinate point of the geometry.  Point 
hasCurves (Read Only)  Returns True if the geometry has a curve.  Boolean 
hullRectangle (Read Only)  A spacedelimited string of the coordinate pairs of the convex hull rectangle.  String 
isMultipart (Read Only)  Returns True if the number of parts for this geometry is more than one.  Boolean 
labelPoint (Read Only)  The point at which the label is located. The labelPoint is always located within or on a feature.  Point 
lastPoint (Read Only)  The last coordinate of the feature.  Point 
length (Read Only)  The length of the linear feature. The calculation uses 2D Cartesian mathematics. For point and multipoint geometry, the length will be zero. For polygon geometry, the length will be the 2D length of the boundary.  Double 
length3D (Read Only)  The 3D length of the linear feature. The calculation uses 3D Cartesian mathematics. For point and multipoint geometry, the length will be zero. For polygon geometry, the length will be the 3D length of the boundary. Caution:The operation does not perform unit conversion between the horizontal and the vertical coordinate systems. The x, y, and z coordinates are assumed to be in the same linear unit. Caution:This property is only available for projected data.  Double 
partCount (Read Only)  The number of geometry parts for the feature.  Integer 
pointCount (Read Only)  The total number of points for the feature.  Integer 
spatialReference (Read Only)  The spatial reference of the geometry.  SpatialReference 
trueCentroid (Read Only)  The center of gravity for a feature.  Point 
type (Read Only)  The geometry type: polygon, polyline, point, multipoint, multipatch, dimension, or annotation.  String 
Method Overview
Method  Explanation 
boundary ()  Constructs the boundary of the geometry. 
buffer (distance)  Constructs a polygon at a specified distance from the geometry. 
clip (envelope)  Constructs the intersection of the geometry and the specified extent. 
contains (second_geometry, {relation})  Indicates if the base geometry contains the comparison geometry. contains is the opposite of within. Only True relationships are shown in this illustration. 
convexHull ()  Constructs the geometry that is the minimal bounding polygon such that all outer angles are convex. 
crosses (second_geometry)  Indicates if the two geometries intersect in a geometry of a lesser shape type. Two polylines cross if they share only points in common, at least one of which is not an endpoint. A polyline and an polygon cross if they share a polyline or a point (for vertical line) in common on the interior of the polygon which is not equivalent to the entire polyline. Only True relationships are shown in this illustration. 
cut (cutter)  Splits this geometry into a part left of the cutting polyline, and a part right of it. When a polyline or polygon is cut, it is split where it intersects the cutter polyline. Each piece is classified as left of or right of the cutter. This classification is based on the orientation of the cutter line. Parts of the target polyline that do not intersect the cutting polyline are returned as part of the right of result for that input polyline. If a geometry is not cut, the left geometry will be empty (None). 
densify (type, distance, {deviation})  Creates a new geometry with added vertices. 
difference (other)  Constructs the geometry that is composed only of the region unique to the base geometry but not part of the other geometry. The following illustration shows the results when the red polygon is the source geometry. 
disjoint (second_geometry)  Indicates if the base and comparison geometries share no points in common. Two geometries intersect if disjoint returns False. Only True relationships are shown in this illustration. 
distanceTo (other)  Returns the minimum distance between two geometries. The distance is in the units of the geometry's spatial reference. If the geometries intersect, the minimum distance is 0. Both geometries must have the same projection. 
equals (second_geometry)  Indicates if the base and comparison geometries are of the same shape type and define the same set of points in the plane. This is a 2D comparison only; M and Z values are ignored. Only True relationships are shown in this illustration. 
generalize (max_offset)  Creates a new simplified geometry using a specified maximum offset tolerance. 
getLength ({measurement_type}, {units})  Returns the length of the feature using a measurement type. 
getPart ({index})  Returns an Array object of Point objects for a particular part of the geometry if an index is specified. If an index is not specified, an Array object containing an Array of Point objects for each geometry part is returned. The getPart method is equivalent to indexing an object; that is, obj.getPart(0) is equivalent to obj[0]. 
intersect (other, dimension)  Constructs a geometry that is the geometric intersection of the two input geometries. Different dimension values can be used to create different shape types. The intersection of two geometries of the same shape type is a geometry containing only the regions of overlap between the original geometries. For faster results, test if the two geometries are disjoint before calling intersect. 
measureOnLine (in_point, {use_percentage})  Returns a measure from the start point of this line to the in_point. 
overlaps (second_geometry)  Indicates if the intersection of the two geometries has the same shape type as one of the input geometries and is not equivalent to either of the input geometries. Only True relationships are shown in this illustration. 
pointFromAngleAndDistance (angle, distance, {method})  Returns a point at a given angle in degrees and distance in the units of the geometry's spatial reference using the specified measurement type. 
positionAlongLine (value, {use_percentage})  Returns a point on a line at a specified distance from the beginning of the line. 
projectAs (spatial_reference, {transformation_name})  Projects a geometry and optionally applies a geotransformation. To project, the geometry must have a spatial reference, and not have an unknown coordinate system. The new spatial reference system passed to the method defines the output coordinate system. If either spatial reference is unknown, the coordinates will not be changed. The z and mvalues are not changed by the projectAs method. 
queryPointAndDistance (in_point, {as_percentage})  Finds the point on the polyline nearest to the in_point and the distance between those points. Also returns information about the side of the line the in_point is on as well as the distance along the line where the nearest point occurs. 
segmentAlongLine (start_measure, end_measure, {use_percentage})  Returns a Polyline between start and end measures. Similar to Polyline.positionAlongLine but will return a polyline segment between two points on the polyline instead of a single point. 
snapToLine (in_point)  Returns a new point based on in_point snapped to this geometry. 
symmetricDifference (other)  Constructs the geometry that is the union of two geometries minus the instersection of those geometries. The two input geometries must be the same shape type. 
touches (second_geometry)  Indicates if the boundaries of the geometries intersect. Two geometries touch when the intersection of the geometries is not empty, but the intersection of their interiors is empty. For example, a point touches a polyline only if the point is coincident with one of the polyline end points. Only True relationships are shown in this illustration. 
union (other)  Constructs the geometry that is the settheoretic union of the input geometries. The two geometries being unioned must be the same shape type. 
within (second_geometry, {relation})  Indicates if the base geometry is within the comparison geometry. within is the opposite operator of contains. Only True relationships are shown in this illustration. The base geometry is within the comparison geometry if the base geometry is the intersection of the geometries and the intersection of their interiors is not empty. within is a Clementini operator, except in the case of an empty base geometry. 
Methods
boundary ()
Data Type  Explanation 
Object  A polygon's boundary is a polyline. A polyline's boundary is a multipoint, corresponding to the endpoints of the line. A point or multipoint's boundary is an empty point or multipoint. 
buffer (distance)
Parameter  Explanation  Data Type 
distance  The buffer distance. The buffer distance is in the same units as the geometry that is being buffered. A negative distance can only be specified against a polygon geometry.  Double 
Data Type  Explanation 
Polygon  The buffered polygon geometry. 
clip (envelope)
Parameter  Explanation  Data Type 
envelope  An Extent object used to define the clip extent.  Extent 
Data Type  Explanation 
Object  An output geometry clipped to the specified extent. 
contains (second_geometry, {relation})
Parameter  Explanation  Data Type 
second_geometry  A second geometry.  Object 
relation  The spatial relationship type.
(The default value is None)  String 
Data Type  Explanation 
Boolean 
A return Boolean value of True indicates this geometry contains the second geometry. 
convexHull ()
Data Type  Explanation 
Object  The resulting geometry. The convex hull of a single point is the point itself. 
crosses (second_geometry)
Parameter  Explanation  Data Type 
second_geometry  A second geometry.  Object 
Data Type  Explanation 
Boolean  A return Boolean value of True indicates the two geometries intersect in a geometry of a lesser shape type. 
cut (cutter)
Parameter  Explanation  Data Type 
cutter  The cutting polyline geometry.  PolyLine 
Data Type  Explanation 
Geometry  A list of two geometries. 
densify (type, distance, {deviation})
Parameter  Explanation  Data Type 
type  The type of densification, DISTANCE, ANGLE, or GEODESIC.
 String 
distance  The maximum distance between vertices. The actual distance between vertices will usually be less than the maximum distance as new vertices will be evenly distributed along the original segment. If using a type of DISTANCE or ANGLE, the distance is measured in the units of the geometry's spatial reference. If using a type of GEODESIC, the distance is measured in meters.  Double 
deviation  Densify uses straight lines to approximate curves. You use deviation to control the accuracy of this approximation. The deviation is the maximum distance between the new segment and the original curve. The smaller its value, the more segments will be required to approximate the curve. If using a type of DISTANCE, the deviation is measured in the units of the geometry's spatial reference. If using a type of ANGLE, the deviation is measured in radians. If using a type of GEODESIC, the deviation is not used.  Double 
Data Type  Explanation 
Geometry  The densified geometry. 
difference (other)
Parameter  Explanation  Data Type 
other  A second geometry.  Object 
Data Type  Explanation 
Object  The resulting geometry. 
disjoint (second_geometry)
Parameter  Explanation  Data Type 
second_geometry  A second geometry.  Object 
Data Type  Explanation 
Boolean  A return Boolean value of True indicates that the two geometries share no points in common. 
distanceTo (other)
Parameter  Explanation  Data Type 
other  A second geometry.  Object 
Data Type  Explanation 
Double  The distance between the two geometries. 
equals (second_geometry)
Parameter  Explanation  Data Type 
second_geometry  A second geometry.  Object 
Data Type  Explanation 
Boolean 
A return Boolean value of True indicates that the two geometries are of the same shape type and define the same set of points in the plane. 
generalize (max_offset)
Parameter  Explanation  Data Type 
max_offset  The maximum offset tolerance.  Double 
Data Type  Explanation 
Geometry  The generalized geometry. 
getLength ({measurement_type}, {units})
Parameter  Explanation  Data Type 
measurement_type  The method used to measure length.
(The default value is GEODESIC)  String 
units  The units in which the length will be calculated.
 String 
Data Type  Explanation 
Double  The length of the feature. By default, for projected coordinate systems, length will be returned in the units of the coordinate system, and for geographic coordinate systems, length will be returned in square meters. 
getPart ({index})
Parameter  Explanation  Data Type 
index  The index position of the geometry.  Integer 
Data Type  Explanation 
Array  The resultant Array object. 
intersect (other, dimension)
Parameter  Explanation  Data Type 
other  The second geometry.  Object 
dimension  The topological dimension (shape type) of the resulting geometry.
 Integer 
Data Type  Explanation 
Object  A new geometry (point, multipoint, polyline, or polygon) that is the geometric intersection of the two input geometries. 
measureOnLine (in_point, {use_percentage})
Parameter  Explanation  Data Type 
in_point  A point (PointGeometry or Point) that is used to measure from the start point of the polyline.  PointGeometry 
use_percentage  If False, the measure will be returned as a distance; if True, the measure will be returned as a percentage. (The default value is False)  Boolean 
Data Type  Explanation 
Double  A distance or percentage. 
overlaps (second_geometry)
Parameter  Explanation  Data Type 
second_geometry  A second geometry.  Object 
Data Type  Explanation 
Boolean  A return Boolean value of True indicates the intersection of the two geometries has the same dimension as one of the input geometries. 
pointFromAngleAndDistance (angle, distance, {method})
Parameter  Explanation  Data Type 
angle  The angle in degrees to the returned point.  Double 
distance  The distance in the units of the geometry's spatial reference to the returned point.  Double 
method  PLANAR measurements reflect the projection of geographic data onto the 2D surface (in other words, they will not take into account the curvature of the earth). GEODESIC, GREAT_ELLIPTIC, LOXODROME, or PRESERVE_SHAPE measurement types can be chosen as an alternative if desired.
(The default value is GEODESIC)  String 
Data Type  Explanation 
PointGeometry  Returns a point at a given angle and distance in degrees and meters. 
positionAlongLine (value, {use_percentage})
Parameter  Explanation  Data Type 
value  The distance along the line. If the distance is less than zero, then the starting point of the line will be returned; if the distance is greater than the length of the line, then the end point of the line will be returned.  Double 
use_percentage  The distance may be specified as a fixed unit of measure or a ratio of the length of the line. If True, value is used as a percentage; if False, value is used as a distance. For percentages, the value should be expressed as a double from 0.0 (0%) to 1.0 (100%). (The default value is False)  Boolean 
Data Type  Explanation 
PointGeometry  The point on the line at a specified distance from the beginning of the line. 
projectAs (spatial_reference, {transformation_name})
Parameter  Explanation  Data Type 
spatial_reference  The new spatial reference. This can be a SpatialReference object or the coordinate system name.  SpatialReference 
transformation_name  The geotransformation name.  String 
Data Type  Explanation 
Object  The projected geometry. 
queryPointAndDistance (in_point, {as_percentage})
Parameter  Explanation  Data Type 
in_point  The input point (PointGeometry or Point).  PointGeometry 
as_percentage  If False, the measure will be returned as a distance; if True, the measure will be returned as a percentage. (The default value is False)  Boolean 
Data Type  Explanation 
tuple  Returns a tuple that includes the following:

segmentAlongLine (start_measure, end_measure, {use_percentage})
Parameter  Explanation  Data Type 
start_measure  The starting distance from the beginning of the line.  Double 
end_measure  The ending distance from the beginning of the line.  Double 
use_percentage  The start and end measures may be specified as fixed units or as a ratio. If True, start_measure and end_measure are used as a percentage; if False, start_measure and end_measure are used as a distance. For percentages, the measures should be expressed as a double from 0.0 (0 percent) to 1.0 (100 percent). (The default value is False)  Boolean 
Data Type  Explanation 
PolyLine  The segment of the line between two points. 
snapToLine (in_point)
Parameter  Explanation  Data Type 
in_point  A point (PointGeometry or Point) to be snapped to the line.  PointGeometry 
Data Type  Explanation 
PointGeometry  The snapped point. 
symmetricDifference (other)
Parameter  Explanation  Data Type 
other  A second geometry.  Object 
Data Type  Explanation 
Object  The resulting geometry. 
touches (second_geometry)
Parameter  Explanation  Data Type 
second_geometry  A second geometry.  Object 
Data Type  Explanation 
Boolean  A return Boolean value of True indicates the boundaries of the geometries intersect. 
union (other)
Parameter  Explanation  Data Type 
other  A second geometry.  Object 
Data Type  Explanation 
Object  The resulting geometry. 
within (second_geometry, {relation})
Parameter  Explanation  Data Type 
second_geometry  A second geometry.  Object 
relation  The spatial relationship type.
(The default value is None)  String 
Data Type  Explanation 
Boolean  A return Boolean value of True indicates this geometry is contained within the second geometry. 
Code sample
Create a polyline feature class from scratch.
import arcpy
# A list of features and coordinate pairs
feature_info = [[[1, 2], [2, 4], [3, 7]],
[[6, 8], [5, 7], [7, 2], [9, 5]]]
# A list that will hold each of the Polyline objects
features = []
for feature in feature_info:
# Create a Polyline object based on the array of points
# Append to the list of Polyline objects
features.append(
arcpy.Polyline(
arcpy.Array([arcpy.Point(*coords) for coords in feature])))
# Persist a copy of the Polyline objects using CopyFeatures
arcpy.CopyFeatures_management(features, "c:/geometry/polylines.shp")