h5pp

h5pp is a high-level C++17 interface for the HDF5 C library. With simplicity in mind, h5pp lets users store common C++ data types into portable binary HDF5 files.

Latest release

Documentation

Go to examples to learn how to use h5pp.

Go to quickstart to see ways of installing h5pp.

Table of Contents

• Introduction
• Features
• Examples
• Get h5pp
• Requirements
• Install
• To-do

Introduction

HDF5 is a portable file format for storing large datasets efficiently. With official low-level API's for C and Fortran, wrappers for C++ and Java and third-party bindings to Python, Julia, Matlab and many others, HDF5 is a great tool for handling data in a collaborative setting.

Although well documented, the low-level C API is vast and using it directly can be challenging. There are many high-level wrappers already that help the user experience, but as a matter of opinion, things could be even simpler.

h5pp is a high-level C++17 interface for the HDF5 C library which aims to be simple to use:

• Read and write common C++ types in a single line of code.
• No prior knowledge of HDF5 is required.
• Meaningful logs and error messages.
• Use HDF5 with modern, idiomatic, type-safe C++17.
• Simple access to HDF5 features like chunking, hyperslabs and compression.
• Simple installation with modular dependencies and opt-in automation.
• Simple documentation (work in progress).

Features

• Header-only C++17 template library.
• High-level front-end to the C API of the HDF5 library.
• Type support:
  • all numeric types: (u)int#_t, float, double, long double.
  • std::complex<> with any of the types above.
  • CUDA-style POD-structs with x,y or x,y,z members as atomic type, such as float3 or double2. These work with any of the types above. In h5pp these go by the name Scalar2<> and Scalar3<>.
  • Contiguous containers with a .data() member, such as std::vector<>.
  • Raw C-style arrays or pointer to buffer + dimensions.
  • Eigen types such as Eigen::Matrix<>, Eigen::Array<> and Eigen::Tensor<>, with automatic conversion to/from row-major storage
  • Text types std::string, char arrays, and std::vector<std::string>.
  • Structs as HDF5 Compound types (example)
  • Structs as HDF5 Tables (with user-defined compound HDF5 types for entries)
• Modern CMake installation of h5pp and its dependencies (opt-in).
• Multi-platform: Linux, Windows, OSX. (Developed under Linux).

Examples

Using h5pp is intended to be simple. After initializing a file, most the work can be achieved using just two member functions .writeDataset(...) and .readDataset(...).

Write an std::vector

    #include <h5pp/h5pp.h>
    int main() {
        std::vector<double> v = {1.0, 2.0, 3.0};    // Define a vector
        h5pp::File file("somePath/someFile.h5");    // Create a file 
        file.writeDataset(v, "myStdVector");        // Write the vector into a new dataset "myStdVector"
    }

Read an std::vector

    #include <h5pp/h5pp.h>
    int main() {
        h5pp::File file("somePath/someFile.h5", h5pp::FileAccess::READWRITE);    // Open (or create) a file
        auto v = file.readDataset<std::vector<double>>("myStdVector");           // Read the dataset from file
    }

Find more code examples in the examples directory.

Get h5pp

There are currently 3 ways to obtain h5pp:

• From conan-center.
• From GitHub.
• As a .deb package from latest release (Ubuntu/Debian only).

Requirements

• C++17 capable compiler. GCC version >= 7 or Clang version >= 7.0
• CMake version >= 3.15
• HDF5 library, version >= 1.8

Optional dependencies

• Eigen >= 3.3.4: Store Eigen containers. Enable with #define H5PP_USE_EIGEN3.
• spdlog >= 1.3.1: Logging library. Enable with #define H5PP_USE_SPDLOG.
• fmt >= 6.1.2: String formatting (used in spdlog). Enable with #define H5PP_USE_FMT.

NOTE: Logging works the same with or without Spdlog enabled. When Spdlog is * not* found, a hand-crafted logger is used in its place to give identical output but without any performance considerations (implemented with STL lists, strings and streams).

Install

Read the instructions here or see installation examples under quickstart. Find a summary below.

Option 1: Install with Conan (Recommended)

Install and configure conan, then run the following command to install from conan center:

> conan install h5pp/1.10.0@ --build=missing

Option 2: Install with CMake

Git clone and build from command line:

    git clone https://github.com/DavidAce/h5pp.git
    mkdir h5pp/build
    cd h5pp/build
    cmake -DCMAKE_INSTALL_PREFIX=<install-dir>  ../
    make
    make install

Read more about h5pp CMake options in the documentation

Option 3: Copy the headers

h5pp is header-only. Copy the files under include to your project and then add #include <h5pp/h5pp.h>.

Read more about linking h5pp to its dependencies here

To-do

• For version 2.0.0
  • Single header
  • Compiled-library mode

In no particular order

• Continue adding documentation
• Expand the pointer-to-data interface
• Expand testing using catch2 for more edge-cases in
  • filesystem permissions
  • user-defined types
  • tables
• Expose more of the C-API:
  • More support for parallel read/write with MPI