FazBrowse GitHub Viewer
|
Trending
|
URL:
|
Home
Tools:
[Download Repo ZIP]
[View Raw Code]
[Original HTTPS Page]
JavaScript/Dynamic-Programming/Shuf.js at master · vdaular-dev/JavaScript · GitHub
vdaular-dev
/
JavaScript
Public
forked from
TheAlgorithms/JavaScript
Notifications
You must be signed in to change notification settings
Fork
0
Star
0
Code
Pull requests
0
Actions
Projects
Security and quality
0
Insights
Additional navigation options
Code
Pull requests
Actions
Projects
Security and quality
Insights
Expand file tree
Breadcrumbs
JavaScript
/
Dynamic-Programming
/
Shuf.js
Copy path
More file actions
More file actions
Latest commit
History
History
History
96 lines (80 loc) · 2.63 KB
Breadcrumbs
JavaScript
/
Dynamic-Programming
/
Shuf.js
Copy path
File metadata and controls
96 lines (80 loc) · 2.63 KB
Raw
Copy raw file
Download raw file
Open symbols panel
Edit and raw actions
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
/*
Given a data set of an unknown size,
Get a random sample in a random order
It's used in data analytics, often as a way to get a small random sample from a data lake or warehouse, or from a large CSV file
*/
function
shuf
(
datasetSource
,
sampleSize
)
{
const
output
=
fillBaseSample
(
datasetSource
,
sampleSize
)
return
randomizeOutputFromDataset
(
datasetSource
,
output
)
}
/**
* Fills the output if possible, with the minimum number of values
*
@param
{
Iterable.<T>
} datasetSource The iterable source of data
*
@param
{
number
} sampleSize The size of the sample to extract from the dataset
*
@returns
{
Array.<T>
} The random sample, as an array
*
@template
T
*/
function
fillBaseSample
(
datasetSource
,
sampleSize
)
{
let
filledIndexes
=
[
]
let
output
=
new
Array
(
sampleSize
)
// Spread data out filling the array
while
(
true
)
{
const
iterator
=
datasetSource
.
next
(
)
if
(
iterator
.
done
)
break
let
insertTo
=
Math
.
floor
(
Math
.
random
(
)
*
output
.
length
)
while
(
filledIndexes
.
includes
(
insertTo
)
)
{
insertTo
++
if
(
insertTo
===
output
.
length
)
{
insertTo
=
0
}
}
output
[
insertTo
]
=
{
value
:
iterator
.
value
}
filledIndexes
=
[
...
filledIndexes
,
insertTo
]
if
(
filledIndexes
.
length
===
sampleSize
)
{
break
}
}
if
(
filledIndexes
.
length
<
output
.
length
)
{
// Not a large enough dataset to fill the sample - trim empty values
output
=
output
.
filter
(
(
_
,
i
)
=>
filledIndexes
.
includes
(
i
)
)
}
return
output
.
map
(
(
o
)
=>
o
.
value
)
}
/**
* Replaces values in the output randomly with new ones from the dataset
*
@param
{
Iterable.<T>
} datasetSource The iterable source of data
*
@param
{
Array.<T>
} output The output so far, filled with data
*
@returns
{
Array.<T>
} The random sample, as an array
*
@template
T
*/
function
randomizeOutputFromDataset
(
datasetSource
,
output
)
{
const
newOutput
=
[
...
output
]
let
readSoFar
=
output
.
length
while
(
true
)
{
const
iterator
=
datasetSource
.
next
(
)
if
(
iterator
.
done
)
break
readSoFar
++
const
insertTo
=
Math
.
floor
(
Math
.
random
(
)
*
readSoFar
)
if
(
insertTo
<
newOutput
.
length
)
{
newOutput
[
insertTo
]
=
iterator
.
value
}
}
return
newOutput
}
// Example
/**
* Generates a random range of data, with values between 0 and 2^31 - 1
*
@param
{
number
} length The number of data items to generate
*
@returns
{
Iterable<number>
} Random iterable data
*/
function
*
generateRandomData
(
length
)
{
const
maxValue
=
Math
.
pow
(
2
,
31
)
-
1
for
(
let
i
=
0
;
i
<
length
;
i
++
)
{
yield
Math
.
floor
(
Math
.
random
(
)
*
maxValue
)
}
}
// const source = generateRandomData(1000)
// const result = shuf(source, 10)
export
{
shuf
,
generateRandomData
}
Back
|
FazBrowse Home
|
New Git URL