Absolute Value
Computes an element-wise absolute value.
The absolute value is defined as
Installation
$ npm install compute-abs
For use in the browser, use browserify.
Usage
var abs = ;
abs( x[, opts] )
Computes an element-wise absolute value. x
may be either a number
, an array
, a typed array
, or a matrix
.
var matrix =datamatouti;out = ;// returns 3out = ;// returns 3data = -2 1 -3 ;out = ;// returns [ 2, 1, 3 ]data = data ;out = ;// returns Float64Array( [2, 1, 3] )data = 6 ;for i = 0; i < 6; i++data i = i - 3;mat = ;/*[ -3 -2-1 01 2 ]*/out = ;/*[ 3 21 01 2 ]*/
The function accepts the following options
:
- accessor: accessor
function
for accessingarray
values. - dtype: output
typed array
ormatrix
data type. Default:float64
. - copy:
boolean
indicating if thefunction
should return a new data structure. Default:true
. - path: deepget/deepset key path.
- sep: deepget/deepset key path separator. Default:
'.'
.
For non-numeric arrays
, provide an accessor function
for accessing array
values.
var data =041-92163-25436;{return d 1 ;}var out =;// returns [ 4, 9, 16, 25, 36 ]
To deepset an object array
, provide a key path and, optionally, a key path separator.
var data ='x':04'x':1-9'x':216'x':3-25'x':436;var out =;/*[{'x':[0,4]},{'x':[1,9]},{'x':[2,16]},{'x':[3,25]},{'x':[4,36]}]*/var bool = data === out ;// returns true
By default, when provided a typed array
or matrix
, the output data structure is float64
in order to preserve precision. To specify a different data type, set the dtype
option (see matrix
for a list of acceptable data types).
var data out;data = -01 01 10 -10 ;out =;// returns Int32Array( [0, 0, 10, 10] )// Works for plain arrays, as well...out =;// returns Uint8Array( [0, 0, 10, 10] )
By default, the function returns a new data structure. To mutate the input data structure (e.g., when input values can be discarded or when optimizing memory usage), set the copy
option to false
.
var databoolmatouti;data = -4 9 -16 ;out =;// returns [ 4, 9, 16 ]bool = data === out ;// returns truedata = 6 ;for i = 0; i < 6; i++data i = i - 3;mat = ;/*[ -3 -2-1 01 2 ]*/out =;/*[ 3 21 01 2 ]*/bool = mat === out ;// returns true
Notes
-
If an element is not a numeric value, the element's absolute value is
NaN
.var data out;out = ;// returns NaNout = ;// returns NaNout = ;// returns NaNout = ;// returns [ 1, NaN, 2 ]{return dx;}data ='x':4'x':-9'x':16'x':null'x':-25'x':36;out =;// returns [ 4, 9, 16, NaN, 25, 36 ]out =;/*[{'x':4},{'x':9},{'x':16},{'x':NaN},{'x':25},{'x':36}]*/ -
Be careful when providing a data structure which contains non-numeric elements and specifying an
integer
output data type, asNaN
values are cast to0
.var out =;// returns Int8Array( [1, 0, 2] );
Examples
var matrix =abs = ;var datamatouttmpi;// Plain arrays...data = 10 ;for i = 0; i < datalength; i++data i = Math*20 - 100;out = ;// Object arrays (accessors)...{return dx;}for i = 0; i < datalength; i++data i ='x': data i;out =;// Deep set arrays...for i = 0; i < datalength; i++data i ='x': i data i x;out =;// Typed arrays...data = 10 ;for i = 0; i < datalength; i++data i = Math*20 - 100;tmp = ;out = '';for i = 0; i < datalength; i++out += tmp i ;if i < datalength-1out += ',';// Matrices...mat = ;out = ;// Matrices (custom output data type)...out =;
To run the example code from the top-level application directory,
$ node ./examples/index.js
Tests
Unit
Unit tests use the Mocha test framework with Chai assertions. To run the tests, execute the following command in the top-level application directory:
$ make test
All new feature development should have corresponding unit tests to validate correct functionality.
Test Coverage
This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:
$ make test-cov
Istanbul creates a ./reports/coverage
directory. To access an HTML version of the report,
$ make view-cov
License
Copyright
Copyright © 2014-2015. The Compute.io Authors.