为什么在类的__init__中调用mpl_connect不起作用?

时间:2019-04-26 11:14:11

标签: python class matplotlib events

当按键或鼠标时,我正在使用“ fig.canvas.mpl_connect(event,function)”制作交互式pyplot图。它按预期工作。但是,为了使其易于导入,我需要将函数压缩到一个类中。 mpl_connect函数将在该类的__init__函数中调用。但是,这使其无法工作。仅当在类外引用类中的函数调用mpl_connect时,它才起作用。

当然,我尝试了不带类的情况下调用它,并且按预期运行。为了表明问题是在类的__init__函数内部发生的,我在类外部调用了mpl_connect来引用类内部的函数。

这是我尝试达到的目标的精简版。这是一个简单的事件处理程序,当您用鼠标单击pyplot图时,可使控制台打印“是”。 :

-> WORKS,尽管没有课程!导入其他程序不可靠。

{
    "size": 0,
    "query": {
        "bool": {
            "filter": {
                "terms": {
                    "compId": [
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                    ]
                }
            },
            "must": {
                "range": {
                    "dateCreated": {
                        "from": "2016-04-01",
                        "to": "2019-03-31",
                        "format": "yyyy-MM-dd"
                    }
                }
            }
        }
    },
    "aggs": {
        "grp_company": {
            "terms": {
                "field": "compId"
            },
            "aggs": {
                "data_per_month": {
                    "date_histogram": {
                        "field": "dateCreated",
                        "interval": "month"
                    }
                },
                "count_buckets": {
                    "stats_bucket": { --> I am getting the count of buckets here
                        "buckets_path": "data_per_month._count"
                    }
                }
            }
        }
    }
}

->不起作用,不打印“是”(即使使用了self.fig。)

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}

->可以了,现在有了一个存储函数的类,但是应该使用对该类的引用,而且看起来不太好:

import matplotlib.pyplot as plt
def abc(event):
   print("yes")
fig, ax = plt.subplots()
fig.canvas.mpl_connect("button_press_event",abc)
plt.show()

我希望在类初始化期间以正常的逻辑pythonic方式调用mpl_connect函数时单击图形时,它会显示“是”。我相信这是一个错误。谢谢。

编辑,通过添加弱引用进行修复。

import matplotlib.pyplot as plt
class test():
    def __init__(self):
        fig, ax = plt.subplots()
        fig.canvas.mpl_connect("button_press_event",self.abc)
    def abc(self, event):
        print("Yes")
test()
plt.show()

1 个答案:

答案 0 :(得分:0)

您将需要保留对由mpl_connect创建的回调ID的引用。 如CallbackRegistry文档字符串所示:

  

在实践中,当不再需要所有回调以避免悬挂引用(从而导致内存泄漏)时,应始终断开所有回调。但是,Matplotlib中的实际代码很少这样做,并且由于其设计,放置此类代码相当困难。为了解决这个问题并防止此类内存泄漏,我们只存储弱引用到绑定的方法,所以当目标对象需要消亡时,CallbackRegistry 不会使其存活。

换句话说,您需要将mpl_connect的返回值分配给实例变量,例如

self.cid = fig.canvas.mpl_connect("button_press_event", self.abc)

类似于您在event handling guide中找到它的方式。