Keywords - Function groups - @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Library: distribs
See also: plothist

Quantlet: empcdf
Description: computes the empirical cdf from a vector of observations.

Usage: {x,y} = empcdf(d{,infsupport,step,noxsort})
Input:
d n x 1 vector, observations
infsupport optional scalar, infimum of the support of the distribution (default: -Inf); enter NaN if you want to omit it
step optional scalar, if zero (default), the output contains the unique jump points and the corresponding values of the empirical cdf; if non-zero, values at the jump points range from the previous to the current value of the empirical cdf so that one can directly plot a step function
noxsort optional scalar, if non-zero, vector x equals d and y contains the appropriately assigned values (0 by default); step and infsupport parameters are ignored
Output:
x m x 1 vector, x-values ascendingly sorted unless noxsort is non-zero
y m x 1 vector, values of the empirical cdf corresponding to x

Example:
library("distribs")
library("plot")
randomize(0)
d = uniform(10)
{x,y} = empcdf(d,0)
x ~ y
{x,y} = empcdf(d,0,1)
line(x~y) ; cdf

Result:
Plots of the empirical distribution and outputs

Contents of _tmp

[ 1,]        0        0
[ 2,]  1.1156e-07      0.1
[ 3,]  0.0030269      0.2
[ 4,]  0.0035468      0.3
[ 5,]  0.12478      0.4
[ 6,]  0.23159      0.5
[ 7,]  0.26201      0.6
[ 8,]  0.42072      0.7
[ 9,]  0.42981      0.8
[10,]  0.60488      0.9
[11,]  0.61585        1
Example:
library("distribs")
library("plot")
d = #(1,2,3,2,4,1,1,5,3,5,2,1,5,1,3,2)
{x,y} = empcdf(d,0)
x ~ y
{x,y} = empcdf(d,0,0,1)
x ~ y
{x,y} = empcdf(d,0,1)
line(x~y) ; cdf

Result:
Plots of the empirical distribution and outputs

Contents of _tmp

[1,]        0        0
[2,]        1   0.3125
[3,]        2   0.5625
[4,]        3     0.75
[5,]        4   0.8125
[6,]        5        1

Contents of _tmp

[ 1,]        1   0.3125
[ 2,]        2   0.5625
[ 3,]        3     0.75
[ 4,]        2   0.5625
[ 5,]        4   0.8125
[ 6,]        1   0.3125
[ 7,]        1   0.3125
[ 8,]        5        1
[ 9,]        3     0.75
[10,]        5        1
[11,]        2   0.5625
[12,]        1   0.3125
[13,]        5        1
[14,]        1   0.3125
[15,]        3     0.75
[16,]        2   0.5625



Author: P. Cizek 20050311
(C) MD*TECH Method and Data Technologies, 05.02.2006