Description
Uniform whole-block position permutation preserving internal order and duplicate display labels.
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.
Uniform whole-block position permutation preserving internal order and duplicate display labels.
When to use this tool
Use this tool to uniform whole-block position permutation preserving internal order and duplicate display labels.
How to use the tool and how it works
- Enter blocksJson, seed using the definitions below. Serialize JSON text fields in the decoded shape shown below.
- Run the operation. Resolve input-format errors before interpreting an output.
- Read result.seed, result.blockOrder, result.blocks, using the stated boundary, ordering, sign and absence conventions.
Require at least two blocks, uniformly shuffle their source indexes using Fisher–Yates and return the reordered whole blocks with blockOrder.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| blocksJson | JSON array of arrays of literal strings, preserving the distinction between block and member positions. | Text, at most 8,192 UTF-16 code units; narrower grammar/range rules also apply. |
| 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. |
These decoded structures show the examples inside JSON text fields. Supply their serialized JSON strings as input.
{
"blocksJson": [
[
"a",
"b"
],
[
"c"
]
]
}| 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.blockOrder | Original block indexes in selected output order. |
| result.blocks | Whole blocks in selected order or within-block permuted position records, as stated above. |
{
"input": {
"blocksJson": "[[\"a\",\"b\"],[\"c\"]]",
"seed": "batch56"
},
"output": {
"result": {
"seed": "batch56",
"blockOrder": [
0,
1
],
"blocks": [
[
"a",
"b"
],
[
"c"
]
]
}
}
}Limitations and assumptions
- Each block’s internal order and contents remain unchanged; empty or equal blocks are still distinct source positions.
- 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 Within-Block Permutation
Independently uniformly permute positions within each fixed block, preserving block order and source indexes.
- Random Bucket Representative Order
Choose uniformly within each nonempty bucket then independently permute representative positions; repeated rendered values remain separate source positions.