如何在元流中创建嵌套分支

Question

我正在使用metaflow创建一个文本处理管道，如下所示：-

___F------
______ D---|          |  
|           |___G---|  |__>  
____B-----|                   |----->H
|          |______E_________________> ^
A -|                                     |
|____C________________________________|

根据文档，branch允许并行计算步骤，并用于并行计算(B，C(、(D，E(和(F，G(。最后，所有分支都在H处连接。以下是实现此逻辑的代码：-

from metaflow import FlowSpec, step
class TextProcessing(FlowSpec):
@step
def a(self):
....
self.next(self.b, self.c)
@step
def c(self):
result1 = {}
....
self.next(self.join)
@step
def b(self):
....
self.next(self.d, self.e)
@step
def e(self):
result2 = []
.....
self.next(self.join)
@step
def d(self):
....
self.next(self.f, self.g)
@step
def f(self):
result3 = []
....
self.next(self.join)
@step
def g(self):
result4 = []
.....
self.next(self.join)

@step
def join(self, results):
data = [results.c.result, results.e.result2, result.f.result3, result.g.result4]
print(data)
self.next(self.end)
@step
def end(self):
pass
etl = TextProcessing()

在运行python main.py run时，我得到以下错误：-

Metaflow 2.2.10 executing TextProcessing for user:ubuntu
Validating your flow...
Validity checker found an issue on line 83:
Step join seems like a join step (it takes an extra input argument) but an incorrect number of steps (c, e, f, g) lead to it. This join was expecting 2 incoming paths, starting from splitted step(s) f, g.

有人能指出我哪里错了吗？

Answer 1

在再次仔细查看文档后，我意识到我没有正确处理联接。根据metaflow-2.2.10:-的文件

注意，您可以任意嵌套分支，也就是说，您可以在分支内部进行分支。只需记住连接您创建的所有分支即可。

这意味着每个分支都应该连接。为了连接来自分支的值，metaflow提供了merge_artifacts实用函数来帮助传播明确的值。

由于工作流中有三个分支，因此添加了三个连接步骤来合并结果。

以下更改对我有效：-

from metaflow import FlowSpec, step
class TextProcessing(FlowSpec):
@step
def a(self):
....
self.next(self.b, self.c)
@step
def c(self):
result1 = {}
....
self.next(self.merge_3)
@step
def b(self):
....
self.next(self.d, self.e)
@step
def e(self):
result2 = []
.....
self.next(self.merge_2)
@step
def d(self):
....
self.next(self.f, self.g)
@step
def f(self):
result3 = []
....
self.next(self.merge_1)
@step
def g(self):
result4 = []
.....
self.next(self.merge_1)
@step
def merge_1(self, results):
self.result = {
'result4' : results.g.result4,
'result3' : results.f.result3
}
self.next(self.merge_2)
@step
def merge_2(self, results):
self.result = { 'result2' : results.e.result2, **results.merge_1.result }
self.merge_artifacts(results, include=['result'])
self.next(self.merge_3)
@step
def merge_3(self, results):
self.result = { 'c' : results.c.result1, **results.merge_2.result }
self.merge_artifacts(results, include=['result'])
self.next(self.end)
@step
def end(self):
print(self.result)
etl = TextProcessing()