如果找到属性，Python创建字典

Question

我正在尝试从多个列表构建字典。问题是，如果给定列表为空，那么我不希望它包含在字典中。

这是可能的键

   'required',
   'as_banner',
   'min',
   'chart_layout',
   'client_name',
   'filter_text',
   'sort_order',
   'chart_type',
   'chart_color',
   'position',
   'order'

这是我构建字典的方法：

propertyDict = dict()
propertyDict["required"] = requiredtype
propertyDict["as_banner"] = as_bannertype
propertyDict["min"] = mintype
propertyDict["chart_layout"] = chart_layouttype
propertyDict["client_name"] = clientnametype
propertyDict["filter_text"] = filter_texttype
propertyDict["sort_order"] = sort_ordertype
propertyDict["chart_type"] = charttype
propertyDict["chart_color"] = chart_colortype
propertyDict["position"] = positiontype
propertyDict["order"] = ordertype

这是我的脚本，如果它存在于“字段”集合中，我将在其中附加键的值。

for table in mtd_tom.Tables:
    if not is_profile_table(table, type="mtd"):
        if table.Description == "Sport Parents (Regrouped)":
            for i, subaxis in enumerate(table.Axes['Side'].SubAxes):
                nField = shatter_sae(subaxis.Specification)['varName']
                field = mdd.Fields[nField]

                if field.Properties.Item['required']:
                    requiredtype.append(field.Properties.Item['required'])
                if field.Properties.Item['as_banner']:
                    as_bannertype.append(field.Properties.Item['as_banner'])
                if field.Properties.Item['min']:
                    mintype.append(field.Properties.Item['min'])
                if field.Properties.Item['chart_layout']:
                    chart_layouttype.append(field.Properties.Item['chart_layout'])
                if field.Properties.Item['client_name']:
                    clientnametype.append(field.Properties.Item['client_name'])
                if field.Properties.Item['filter_text']:
                    filter_texttype.append(field.Properties.Item['filter_text']) 
                if field.Properties.Item['sort_order']:
                    sort_ordertype.append(field.Properties.Item['sort_order'])   
                if field.Properties.Item['chart_type']:                
                    charttype.append(field.Properties.Item['chart_type'])
                if field.Properties.Item['chart_color']:
                    chart_colortype.append(field.Properties.Item['chart_color'])
                if field.Properties.Item['position']:
                    positiontype.append(field.Properties.Item['position'])
                if field.Properties.Item['order']:
                    ordertype.append(field.Properties.Item['order'])                        
                else:
                    print "%s not found" % properties[i]

这是现在的输出：

{'as_banner': [], 'chart_color': ['green', 'pink', 'green', 'green', 'green', 'orange', 'yellow', 'white'], 'chart_layout': ['1', '2', '3', '4', '5', '6', '7', '8'], 'sort_order': ['asending', 'desending', 'asending', 'desending', 'asending', 'asending', 'asending', 'desending'], 'chart_type': ['bar', 'WeightedBar', 'column', 'pie', 'line', 'column', 'line', 'pie'], 'client_name': ['Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)'], 'filter_text': [], 'required': [], 'position': [], 'min': [], 'order': []}

注意，我不希望包含空值的键...

而且我不想创建一个列表的副本，其中不包括具有空值的键...

关于如何做到这一点的任何建议？

Answer 1

在构建字典后过滤掉空列表可能是最简单的：

propertyDict = {k: v for k, v in propertyDict.iteritems() if v}

另一种方法是在循环中构建字典，并且只在添加到列表时添加新的键值对； collections.defaultdict() instance 会更容易

from collections import defaultdict

propertyDict = defaultdict(list)
properties = ('required', 'as_banner', 'min', 'chart_layout', 'client_name',
              'filter_text', 'sort_order', 'chart_type', 'chart_color',
              'position', 'order')

for i, subaxis in enumerate(table.Axes['Side'].SubAxes):
    nField = shatter_sae(subaxis.Specification)['varName']
    field = mdd.Fields[nField]
    for prop in properties:
        value = field.Properties.Item[prop]
        if value:
            propertyDict[prop].append(value)

# optional, turn `defaultdict` back into a `dict` object. This step is really
# not needed unless you need the `defaultdict.__missing__` behaviour to cease for
# later code.
# propertyDict = dict(propertyDict)

通过使用属性名称列表进行测试，此代码非常更简单

Answer 2

使用 dict-comprehension 过滤掉空键：

>>> d = {'as_banner': [], 'chart_color': ['green', 'pink', 'green', 'green', 'green', 'orange', 'yellow', 'white'], 'chart_layout': ['1', '2', '3', '4', '5', '6', '7', '8'], 'sort_order': ['asending', 'desending', 'asending', 'desending', 'asending', 'asending', 'asending', 'desending'], 'chart_type': ['bar', 'WeightedBar', 'column', 'pie', 'line', 'column', 'line', 'pie'], 'client_name': ['Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)'], 'filter_text': [], 'required': [], 'position': [], 'min': [], 'order': []}
>>> {k:v for k, v in d.iteritems() if v}
{'chart_layout': ['1', '2', '3', '4', '5', '6', '7', '8'], 'client_name': ['Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)'], 'chart_color': ['green', 'pink', 'green', 'green', 'green', 'orange', 'yellow', 'white'], 'sort_order': ['asending', 'desending', 'asending', 'desending', 'asending', 'asending', 'asending', 'desending'], 'chart_type': ['bar', 'WeightedBar', 'column', 'pie', 'line', 'column', 'line', 'pie']}

适用于 Python2.6 及更早版本：

dict(((k, v) for k, v in d.iteritems() if v))

要更新原始字典本身，请在具有空值的键上使用 del：

>>> for k, v in d.items():
    if not v:
        del d[k]

>>> d
{'chart_layout': ['1', '2', '3', '4', '5', '6', '7', '8'], 'chart_color': ['green', 'pink', 'green', 'green', 'green', 'orange', 'yellow', 'white'], 'chart_type': ['bar', 'WeightedBar', 'column', 'pie', 'line', 'column', 'line', 'pie'], 'client_name': ['Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)', 'Sport Parents (Regrouped)'], 'sort_order': ['asending', 'desending', 'asending', 'desending', 'asending', 'asending', 'asending', 'desending']}

Answer 3

将您的类型放入列表中。循环遍历字典和列表。大功告成！

types = [requiredtype, as_bannertype, ..]
for k, v in propertyDict.items():
    for t in types:
        if v:
            t.append(v)