配置字典中的继承

Question

我想要的是

从yaml配置我得到一个python字典,如下所示:

conf = {
    'cc0': {
        'subselect': 
            {'roi_spectra': [0], 'roi_x_pixel_spec': 'slice(400, 1200)'},
        'spec': 
            {'subselect': {'x_property': 'wavenumber'}},

        'trace': 
            {'subselect': {'something': 'jaja', 'roi_spectra': [1, 2]}}
    }
}

如您所见,关键字"subselect"对于所有子级别都是通用的,其值始终是dict,但它的存在是可选的.嵌套量可能会改变.我正在寻找一个功能,允许我执行以下操作:

# desired function that uses recursion I belive.
collect_config(conf, 'trace', 'subselect')

其中'trace'是dicts字典的关键,可能是'subselect'字典作为值.

它应该回来

{'subselect':{
    'something': 'jaja', 
    'roi_spectra': [1, 2], 
    'roi_x_pixel_spec': 
    'slice(400, 1200)'
}

或者如果我要求

collect_config(conf, "spec", "subselect")

它应该回来

{'subselect':{
    'roi_spectra': [0], 
    'roi_x_pixel_spec': 
    'slice(400, 1200)',
    'x_property': 'wavenumber'
}

我基本上想要的是一种方法,将键的值从顶层传递到较低层,并使较低层覆盖顶层值. 很像类的继承,但有字典.

所以我需要一个横跨dict的函数,找到一个到达所需键的路径(这里是"trace"或"spec"并用更高级别的值填充它的值(这里是"subselect"),但只有更高的值级别值不存在.

一个糟糕的解决方案

我目前有一种看起来如下的实现.

# This traverses the dict and gives me the path to get there as a list.
def traverse(dic, path=None):
    if not path:
        path=[]
    if isinstance(dic, dict):
        for x in dic.keys():
            local_path = path[:]
            local_path.append(x)
            for b in traverse(dic[x], local_path):
                 yield b
    else:
        yield path, dic

# Traverses through config and searches for the property(keyword) prop.
# higher levels will update the return
# once we reached the level of the name (max_depth) only 
# the path with name in it is of interes. All other paths are to
# be ignored.
def collect_config(config, name, prop, max_depth):
    ret = {}
    for x in traverse(config):
        path = x[0]
        kwg = path[-1]
        value = x[1]
        current_depth = len(path)
        # We only care about the given property.
        if prop not in path:
            continue
        if current_depth < max_depth or (current_depth == max_depth and name in path):
            ret.update({kwg: value})
    return ret

我可以随叫它

read_config(conf, "trace", 'subselect', 4)

得到

{'roi_spectra': [0],
 'roi_x_pixel_spec': 'slice(400, 1200)',
 'something': 'jaja'}

更新

jdehesa几乎就在那里,但我也可以有一个看起来像这样的配置:

conf = {
    'subselect': {'test': 'jaja'}
    'bg0': {
      'subselect': {'roi_spectra': [0, 1, 2]}},
    'bg1': {
      'subselect': {'test': 'nene'}},
}

collect_config(conf, 'bg0', 'subselect')

{'roi_spectra': [0, 1, 2]} 

代替

{'roi_spectra': [0, 1, 2], 'test': 'jaja'}

Answer 1

这是我的看法：

def collect_config(conf, key, prop, max_depth=-1):
    prop_val = conf.get(prop, {}).copy()
    if key in conf:
        prop_val.update(conf[key].get(prop, {}))
        return prop_val
    if max_depth == 0:
        return None
    for k, v in conf.items():
        if not isinstance(v, dict):
            continue
        prop_subval = collect_config(v, key, prop, max_depth - 1)
        if prop_subval is not None:
            prop_val.update(prop_subval)
            return prop_val
    return None

conf = {
    'cc0': {
        'subselect': 
            {'roi_spectra': [0], 'roi_x_pixel_spec': 'slice(400, 1200)'},
        'spec': 
            {'subselect': {'x_property': 'wavenumber'}},

        'trace': 
            {'subselect': {'something': 'jaja', 'roi_spectra': [1, 2]}}
    }
}
print(collect_config(conf, "trace", 'subselect', 4))
>>> {'roi_x_pixel_spec': 'slice(400, 1200)',
     'roi_spectra': [1, 2],
     'something': 'jaja'}

conf = {
    'subselect': {'test': 'jaja'},
    'bg0': {
      'subselect': {'roi_spectra': [0, 1, 2]}},
    'bg1': {
      'subselect': {'test': 'nene'}},
}
print(collect_config(conf, 'bg0', 'subselect'))
>>> {'roi_spectra': [0, 1, 2], 'test': 'jaja'}

离开max_depth时-1将conf无深度限制地穿越。