9monkeys 9monkeys - 1 year ago 142
Python Question

Parsing a YAML file in Python, and accessing the data?

I am new to YAML and have been searching for ways to parse a YAML file and use/access the data from the parsed YAML.

I have come across explanations on how to parse the YAML file, for example, the PyYAML tutorial, "How can I parse a YAML file", "Convert Python dict to object?", but what I haven't found is a simple example on how to access the data from the parsed YAML file.

Assume I have a YAML file such as:

branch1: branch1 text
branch2: branch2 text

How do I access the text "branch1 text"?

"YAML parsing and Python?" provides a solution, but I had problems accessing the data from a more complex YAML file. And, I'm wondering if there is some standard way of accessing the data from a parsed YAML file, possibly something similar to "tree iteration" or "elementpath" notation or something which would be used when parsing an XML file?

Answer Source

Since PyYAML's yaml.load() function maps YAML documents to native Python data structures, you can just access items by key or index. Using the example from the question you linked:

import yaml
with open('tree.yaml', 'r') as f:
    doc = yaml.load(f)

To access "branch1 text" you would use:

txt = doc["treeroot"]["branch1"]
print txt
"branch1 text"

because, in your YAML document, the value of the branch 1 key is under the treeroot key.

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