Description
Uniformly permute only unpinned positions; supplied pinned source positions remain in the same output slots.
A random construction is defined by its sampling support: positions, permutations, complete tilings, proposal sequences or another explicit set. Uniform choices at one stage do not necessarily make final visible outcomes uniform. A replay seed gives a deterministic sequence; equal values can hide different sampled positions. These tools are for reproducible synthetic examples rather than cryptographic entropy.
Uniformly permute only unpinned positions; supplied pinned source positions remain in the same output slots.
When to use this tool
Use this tool to uniformly permute only unpinned positions; supplied pinned source positions remain in the same output slots.
How to use the tool and how it works
- Enter values, pinned, seed using the definitions below.
- Run the operation. Resolve input-format errors before interpreting an output.
- Read result.seed, result.sourceIndexes, result.values, using the stated boundary, ordering, sign and absence conventions.
Validate distinct pinned indexes. Keep each pinned source position fixed, Fisher–Yates shuffle only unpinned source indexes and return that complete index map with values.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| values | Literal string values in original positional order; repeated spellings retain distinct source indexes. | Dense list of at most 128 literal strings, each at most 8,192 UTF-16 units. |
| pinned | Distinct zero-based source positions that must remain fixed. | Dense list of at most 128 finite numbers, under the stated integer/range rules. |
| seed | Nonblank replay seed, at most 256 UTF-16 code units; an injected source overrides seeded draws. | Text, at most 8,192 UTF-16 code units; narrower grammar/range rules also apply. |
| Output field | Interpretation |
|---|---|
| result | Object containing the fields below. |
| result.seed | Original supplied seed string; injected-source replay additionally requires that source’s state. |
| result.sourceIndexes | Output-position-to-original-position map. |
| result.values | Generated/reordered literal values, preserving the stated positional support. |
{
"input": {
"values": [
"a",
"b",
"c"
],
"pinned": [
1
],
"seed": "batch56"
},
"output": {
"result": {
"seed": "batch56",
"sourceIndexes": [
0,
1,
2
],
"values": [
"a",
"b",
"c"
]
}
}
}Limitations and assumptions
- At least two unpinned positions are required. Repeated values remain distinct source positions and can conceal a changed permutation.
- A nonblank seed of at most 256 UTF-16 code units is required. With ordinary use the seed initializes one deterministic advancing source; an application-injected random source takes precedence and the seed alone then cannot replay the result. Uniformity statements assume independent uniform source draws in [0,1). Source calls are bounded and degenerate injected sources can fail a rejection budget. This is not cryptographically secure.
- Every declared outer field is required and unknown outer fields are rejected. Strings and JSON text have size limits, lists are bounded to 128 entries, and JSON nesting/node counts are bounded. Tighter operation-specific bounds stated above take precedence.
- Ordinary numeric outputs must be finite and within safe-integer magnitude. Exact large lengths/counts use decimal strings. Original record indexes and code-unit positions are zero-based; span ends are exclusive unless stated otherwise.
Alternative or Complementary methods
Choose a generator whose support matches the intended experiment and retain source-position provenance. Use a separate statistically justified process model or cryptographic source where those properties matter.
References
Similar or alternative tools
- Random Block Order Permutation
Uniform whole-block position permutation preserving internal order and duplicate display labels.
- Random Empty Slot Item Placement
Assign unique supplied item IDs to distinct currently empty integer slots without replacement; report actual slot IDs, preserve occupied slots.