确定 HDF5 路径的对象类型

Question

我有一个路径名（一个字符串）和一个打开的 HDF5 文件。我已经使用 H5Lexists 来确保存在具有该名称的对象。如何确定对象类型是什么？例如数据集、组等

// open the file
hid_t fapl = H5Pcreate(H5P_FILE_ACCESS);  
H5Pset_fclose_degree(fapl, H5F_CLOSE_STRONG);
hid_t hid = H5Fopen(filename.c_str(), H5F_ACC_RDONLY, fapl);

// ensure the object exists
const string path = "/some/path/to/an/object";
if (H5Lexists(m_hid, path.c_str(), H5P_DEFAULT) < 0) throw runtime_error();

// determine the object type
// TODO
if (dataset) {
    hid_t dataset = H5Dopen(hid, path.c_str(), H5P_DEFAULT);
    // do something
}
else if (group) {
    hid_t group = H5Gopen(hid, path.c_str(), H5P_DEFAULT);
    // do something
}
H5Fclose(hid);

我尽量不使用基于 C++ class 的接口，因为它已被添加到遗留代码中。我尝试只打开数据集以查看是否 dataset < 0 以确定它是否是数据集，但是，HDF5 库向 stderr 抛出大量警告，所以我想以正确的方式进行操作。

Answer 1

用H5Oopen if you don't know the type in advance and use H5Iget_type判断。

hid_t object = H5Oopen(hid, path.c_str(), H5P_DEFAULT);
H5I_type_t h5type = H5Iget_type(object);

if (h5type == H5I_BADID) {
    ... // error handling stuff
} else if (h5type == H5I_DATASET) {
    ... // dataset stuff
} else if (h5type == H5I_GROUP) {
    ... // group stuff
} else { // other stuff maybe
}

H5Oclose(hid);

Answer 2

如果您没有绑定到特定的库，您可能想看看 HDFql，因为它大大减轻了您对 HDF5 的 low-level 细节的负担。使用HDFql，你的use-case在C中可以如下解决（原则上不会产生错误信息）：

int type;

if (hdfql_execute("SHOW TYPE /some/path/to/an/object") == HDFQL_SUCCESS)
{
    hdfql_cursor_next(NULL);
    type = *hdfql_cursor_get_int(NULL);
    if (type == HDFQL_GROUP)
    {
        printf("Object is a group\n");
    }
    else if (type == HDFQL_DATASET)
    {
        printf("Object is a dataset\n");
    }
    else if (type == HDFQL_ATTRIBUTE)
    {
        printf("Object is an attribute\n");
    }
    else if (type == HDFQL_SOFT_LINK)
    {
        printf("Object is a soft link\n");
    }
    else if (type == HDFQL_EXTERNAL_LINK)
    {
        printf("Object is an external link\n");
    }
    else if (type == HDFQL_SOFT_LINK | HDFQL_GROUP)
    {
        printf("Object is a soft link pointing to a group\n");
    }
    else if (type == HDFQL_SOFT_LINK | HDFQL_DATASET)
    {
        printf("Object is a soft link pointing to a dataset\n");
    }
    else if (type == HDFQL_EXTERNAL_LINK | HDFQL_GROUP)
    {
        printf("Object is an external link pointing to a group\n");
    }
    else if (type == HDFQL_EXTERNAL_LINK | HDFQL_DATASET)
    {
        printf("Object is an external link pointing to a dataset\n");
    }
    else
    {
        printf("Object is of unknown type!\n");
    }
}
else
{
    printf("Object was not found!");
}

Answer 3

图书馆的 H5O 部分就是答案。此外，H5Lexists 也不是确定对象是否存在的正确方法，因此我也对其进行了更新。

// open the file
hid_t fapl = H5Pcreate(H5P_FILE_ACCESS);  
H5Pset_fclose_degree(fapl, H5F_CLOSE_STRONG);
hid_t hid = H5Fopen(filename.c_str(), H5F_ACC_RDONLY, fapl);

// ensure the object exists
const string path = "/some/path/to/an/object";
if (H5Oexists_by_name(hid, path.c_str(), H5P_DEFAULT) <= 0) throw runtime_error();

// determine the object type
H5O_info_t info;
H5Oget_info_by_name(m_hid, parent.c_str(), &info, H5P_DEFAULT);
if (info.type == H5O_TYPE_DATASET) {
    hid_t dataset = H5Dopen(hid, path.c_str(), H5P_DEFAULT);
    // do something
}
else if (info.type == H5O_TYPE_GROUP) {
    hid_t group = H5Gopen(hid, path.c_str(), H5P_DEFAULT);
    // do something
}
H5Fclose(hid);

确定 HDF5 路径的对象类型

Determine the object type of a HDF5 path

c++

hdf5