python根据key对流做join

最新推荐文章于 2025-02-11 14:00:15 发布

原创最新推荐文章于 2025-02-11 14:00:15 发布 · 610 阅读

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#python #join #key

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这篇博客介绍了如何使用Python根据key对流数据进行join操作。通过示例展示了使用`keyjoin`函数，结合`instreams`和`keyindexs`参数，将两个流数据迭代器按key值匹配并合并。

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<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);"></span><pre name="code" class="python">def keyjoin(instreams,keyindexs=None,default=None):
    '''把各流进行关联，instreams是流数组，每个流中的数据类型为list或tuple
    indexss是用于把流数据关联在一起的字段索引，每个流对应一个索引数组'''
    if not keyindexs:
        keyindexs = [ () for s in instreams ]
    if not default:
        default = [ () for s in instreams ]
    data = [ () for s in instreams ]
    livings = set(list(range(len(instreams))))
    togets = list(range(len(instreams)))
    while True:
        for toget in togets:
            if toget in livings:
                try:
                    data[toget] = instreams[toget].next()
                except:
                    livings.remove(toget)
        if not livings:
            raise StopIteration
        keys = [[record[index] if record else () for index in keyindexs[i]] for i,record in enumerate(data)]
        key = min(keys)
        result = [data[i] if keys[i]==key else default[i] for i,record in enumerate(data)]
        yield result
        data = [data[i] if keys[i]!=key else () for i,record in enumerate(data)]
        togets = [i if keys[i]==key else () for i,record in enumerate(data)]

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">>>> stream1</span>

[['il', 10], ['ls', 12]]
>>> stream2

[['ls', 22.199999999999999], ['zs', 21.100000000000001]]

>>> for data in keyjoin(instreams=[iter(stream1),iter(stream2)],keyindexs=[[0],[0]]):
... print data
...
[['il', 10], ()]
[['ls', 12], ['ls', 22.199999999999999]]
[(), ['zs', 21.100000000000001]]