I'm using the Python library glom to extract data from a dictionary that contains lists.
This question is about unterstanding how glom works with user defined functions and how I can move data from lists into dictionaries within glom.
As an example, I'm trying to convert the data into a dictionary directly.
# in the real world, this data has way many more fields
data = {'vessels': [{'aisStatic': {'mmsi': 1, 'name': 'name1'}},
{'aisStatic': {'mmsi': 2, 'name': 'name2'}}],
'timestamp': None}
# this is the glob spec to extract the data
spec = ('vessels',[({'mmsi':'aisStatic.mmsi','name':'aisStatic.name'})])
# an example to generate a new key based on data & position
def keyfunc(i, v):
return f"v{i}-{v['mmsi']}"
result = glom(data, spec)
wanted_result = {keyfunc(i,v): v for i, v in enumerate(result)}
The wanted result looks like this
{'v0-1': {'mmsi': 1, 'name': 'name1'}, 'v1-2': {'mmsi': 2, 'name': 'name2'}}
For the example, I'm using a comprehension outside of glom to get the wanted result, since glom returns a list.
I am looking at a way to get the same results directly via a glom spec.
A working solution is to use Invoke on the enumerate function.
from glom import merge, Invoke
data = {
"vessels": [
{"aisStatic": {"mmsi": 1, "name": "name1"}},
{"aisStatic": {"mmsi": 2, "name": "name2"}},
],
"timestamp": None,
}
spec = (
"vessels",
[{"mmsi": "aisStatic.mmsi", "name": "aisStatic.name"}],
Invoke(enumerate).specs(T),
[lambda x: {f"v{x[0]}-{x[1].get('mmsi')}": x[1]}],
merge,
)
print(glom(data, spec))
which returns the requested result
{'v0-1': {'mmsi': 1, 'name': 'name1'}, 'v1-2': {'mmsi': 2, 'name': 'name2'}}