agg_block_size

C++ Function Reference

1 Signature

hsize_t BigDataStatMeth::agg_block_size(Rcpp::Nullable< int > wsize, hsize_t iterated, hsize_t fixed)

2 Description

Choose a block size for aggregation.

3 Parameters

wsize (Rcpp::Nullable< int >): User-supplied block size (Nullable).
iterated (hsize_t): Size of the dimension being blocked (must be > 0).
fixed (hsize_t): Size of the dimension that is always read completely.

4 Returns

Block size in [1, iterated].

5 Details

If the user supplied wsize, it is used directly (clamped to [1, iterated]). Otherwise the block size is set so that one block occupies at most MAXELEMSINBLOCK elements (fixed_dim × block_size).

6 Caller Graph

7 Source Code

Implementation

File: inst/include/hdf5Algebra/matrixAggregations.hpp • Lines 89-106

inline hsize_t agg_block_size(Rcpp::Nullable<int> wsize,
                               hsize_t iterated,
                               hsize_t fixed)
{
    hsize_t bs;
    if (wsize.isNotNull()) {
        bs = static_cast<hsize_t>(std::max(1, Rcpp::as<int>(wsize)));
    } else {
        // Default: one block holds at most MAXELEMSINBLOCK elements
        bs = (fixed > 0)
            ? std::max(static_cast<hsize_t>(1),
                       static_cast<hsize_t>(
                           std::ceil(static_cast<double>(MAXELEMSINBLOCK) / fixed)))
            : iterated;
    }
    // Never exceed the actual dimension
    return std::min(bs, iterated);
}

8 Usage Example

#include "BigDataStatMeth.hpp"

// Example usage
auto result = agg_block_size(...);

---
title: "agg_block_size"
subtitle: "C++ Function Reference"
---

## Signature

```cpp
hsize_t BigDataStatMeth::agg_block_size(Rcpp::Nullable< int > wsize, hsize_t iterated, hsize_t fixed)
```

## Description

Choose a block size for aggregation.

## Parameters

- `wsize` (`Rcpp::Nullable< int >`): User-supplied block size (Nullable).
- `iterated` (`hsize_t`): Size of the dimension being blocked (must be > 0).
- `fixed` (`hsize_t`): Size of the dimension that is always read completely.

## Returns

Block size in [1, iterated].

## Details

If the user supplied wsize, it is used directly (clamped to [1, iterated]). Otherwise the block size is set so that one block occupies at most MAXELEMSINBLOCK elements (fixed_dim × block_size).

## Caller Graph

::: {.diagram-section}
<object type="image/svg+xml" data="images/namespace_big_data_stat_meth_a8c0da1e3336ab75efdb53cdd7707ae99_icgraph.svg" class="class-diagram">
  <img src="images/namespace_big_data_stat_meth_a8c0da1e3336ab75efdb53cdd7707ae99_icgraph.svg" alt="Function dependencies"/>
</object>
:::

## Source Code

::: {.callout-note collapse="true"}
### Implementation

**File:** `inst/include/hdf5Algebra/matrixAggregations.hpp` • **Lines 89-106**

```cpp
inline hsize_t agg_block_size(Rcpp::Nullable<int> wsize,
                               hsize_t iterated,
                               hsize_t fixed)
{
    hsize_t bs;
    if (wsize.isNotNull()) {
        bs = static_cast<hsize_t>(std::max(1, Rcpp::as<int>(wsize)));
    } else {
        // Default: one block holds at most MAXELEMSINBLOCK elements
        bs = (fixed > 0)
            ? std::max(static_cast<hsize_t>(1),
                       static_cast<hsize_t>(
                           std::ceil(static_cast<double>(MAXELEMSINBLOCK) / fixed)))
            : iterated;
    }
    // Never exceed the actual dimension
    return std::min(bs, iterated);
}
```
:::

## Usage Example

```cpp
#include "BigDataStatMeth.hpp"

// Example usage
auto result = agg_block_size(...);
```