# Line Statistics (Spatial Analyst)

## Summary

Calculates a statistic on the attributes of lines in a circular neighborhood around each output cell.

## Usage

• Only the part of a line within the neighborhood is considered for the Majority, Mean, Median and Minority statistics. For the others, it does not matter whether a part or the whole line is used.

• If there are no lines in the neighborhood of a raster cell, the Variety statistic assigns a value of zero. For the other statistics, NoData is assigned.

• The statistic types Majority, Mean, Median, and Minority are weighted according to the length of the lines. If a line is twice as long as another, its value is considered to occur twice as often.

• The values on the output raster will always be integer in the case of Variety. They will always be floating point for Mean. For the other statistics, the output data type is the same as the input item value type.

• When the field is integer, the available overlay statistic choices are Mean, Majority, Maximum, Median, Minimum, Minority, Range, and Variety. When the field is floating point, the only allowed statistics are Mean, Maximum, Minimum, and Range.

• For statistic types Majority, Maximum, Median, Minimum, Minority, and Range, the output data type of the raster will be the same as the input field type. For statistics type Mean, the output raster will always be floating point. For Variety, the output raster will always be integer.

## Syntax

LineStatistics (in_polyline_features, field, {cell_size}, {search_radius}, {statistics_type})
 Parameter Explanation Data Type in_polyline_features The input polyline features for which to calculate the Line Statistics. Feature Layer field Field can be any numeric field of the input line features. It can be the Shape field if the input features contains z. Field cell_size(Optional) Cell size for output raster dataset. This is the value in the environment if specifically set. If not set in the environment, it is the shorter of the width or height of the extent of the input feature dataset, in the output spatial reference, divided by 250. Analysis cell size search_radius(Optional) Search radius to calculate the desired statistic within, in map units. The default radius is five times the output cell size. Double statistics_type(Optional) The Statistic type to be calculated. Statistics are calculated on the value of the specified field for all lines in the neighborhood. MEAN — Calculates the average field value in each neighborhood, weighted by the length.The form of the calculation is:Mean = (sum of (length * field_value)) / (sum_of_length) Only the part of the length that falls within the neighborhood is used. MAJORITY — Determines the value having the greatest length of line in the neighborhood. MAXIMUM —Determines the largest value in the neighborhood. MEDIAN — Determines the median value, weighted by the length.Conceptually, all line segments in the neighborhood are sorted by value and placed end-to-end in a straight line. The value of the segment at the midpoint of the straight line is the median. MINIMUM — Calculates smallest value in each neighborhood. MINORITY — The value having the least length of line in the neighborhood. RANGE — The range of values (maximum–minimum). VARIETY — The number of unique values. String

#### Return Value

 Name Explanation Data Type out_raster The output line statistics raster. Raster

## Code Sample

LineStatistics example 1 (Python window)

This example calculates the average length of line segments within a certain radius of each cell in the input raster.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
lineStatOut = LineStatistics("streams", "LENGTH", 50, 500, "MEAN")
lineStatOut.save("C:/sapyexamples/output/linestatout")
LineStatistics example 2 (stand-alone script)

This example calculates the average length of line segments within a certain radius of each cell in the input raster.

# Name: LineStatistics_Ex_02.py
# Description:
# Requirements: Spatial Analyst Extension
# Author: ESRI

# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *

# Set environment settings
env.workspace = "C:/sapyexamples/data"

# Set local variables
inLines = "streams.shp"
field = "LENGTH"
cellSize = 50

# Check out the ArcGIS Spatial Analyst extension license
arcpy.CheckOutExtension("Spatial")

# Execute LineStatistics
lineStatOut = LineStatistics(inLines, field, cellSize, searchRadius,
"MEAN")

# Save the output
lineStatOut.save("C:/sapyexamples/output/linestatisout")

## Licensing Information

ArcView: Requires Spatial Analyst
ArcEditor: Requires Spatial Analyst
ArcInfo: Requires Spatial Analyst

6/29/2011