For 循环 HDF5 文件中的单个字符串值

Question

我正在尝试编写一个脚本来读取一个特定的 hdf5 文件，该文件有一个名为 ElementAbundance 的字段，其中包含化学元素的 araays 分数值。

这就是我正在做的，我打开 hdf5 文件，我列出了该文件中的字段。如果文件有 ElementAbundance，它将检查我在 field 中请求的元素是否在 elements 数组中。如果它在数组中，那么我想 return 我要求的元素作为单个字符串。

我在别处查过了 ElementAbundance 中的字段是

elements = ['Carbon', 'Helium', 'Hydrogen', 'Iron', 'Magnesium', 'Neon', 'Nitrogen', 'Oxygen', 'Silicon']

import h5py
from particleType import partTypeNum # This is another file that is unimportant in regards to my question

# Only necessary if gas (0) particle type

def loadElement(basePath,snapNum,partType,field=None):
    result = {}

    # This uses the above module to associate keys words with the letter 0    
    ptNum = partTypeNum(partType)
    gName = "PartType" + str(ptNum)

    # making sure fields is not a single element
    if isinstance(field, basestring):
        field = [field]

    # begin by opening the h5py file
    with h5py.File(snapPath(basePath,snapNum),'r') as f:

        # header = dict( f['Header'].attrs.items() )
        # nPart = getNumPart(header)

        # This creates a list for all the fields in the HDF5 file
        field_list = []
        for i in f[gName].keys():
            field_list.append(str(i))

        # This will check if the file has a "ElementAbundance" header
        for i in enumerate(field_list):
            # if the string is not inside the list, we raise an exception
            if "ElementAbundance" not in field_list:
                raise Exception("Particle type ["+str(ptNum)+"] does not have a field of elements")
            # If it is, we extract the chemical elements from inside the element abundance field.
            else:
                g = f[gName]['ElementAbundance'] # file contains elements
                elements = []
                for j in g.keys():
                    elements.append(str(j))


        # now for looping the lists values with their index
        for i,element in enumerate(elements):
            # if the element field is inside the elements list, we retrieve that element as a string
            if field == element:
                the_element = str(elements[i])
                return the_element
            # if their is a ElementAbundance field but the asked for field element is not in that list, raise and exception.
            else:
                raise Exception("Element type ["+str(field)+"] not found in element abundance list.")

        f.close()
    # testing to see if the above for loop returns a single string
    return the_element

现在我测试它是否 return 是字符串 'Hydrogen'，但我 returned 有一个例外：Exception: Element type [['Hydrogen']] not found in element abundance list.

这很奇怪，因为 Hydrogen 应该在我制作的 elements 列表中。此外，引发的异常应该 return ['Hydrogen'] 而不是 [['Hydrogen']].

如果我可以添加任何其他信息，请告诉我！

Answer 1

如果您将函数调用为：

loadElement(basePath,snapNum,partType,field='Hydrogen')

然后'Hydrogen'变成单项列表在：

if isinstance(field, basestring):
        field = [field]

当您迭代元素列表时，您是在迭代字符串并将它们与列表匹配 ['Hydrogen']，因此找不到匹配项。

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