On Thu, Aug 11, 2016 at 10:57 AM Malcolm Greene <pyt...@bdurham.com> wrote:
> Background: I'm building a rules engine for transforming rows of data
> being returned by csv DictReader, eg. each row of data is a dict of column
> name to value mappings. My rules are a list of rule objects whose
> attributes get referenced by rule specific methods. Each rule has an
> associated method which gets called based on rule name.
>
Could you share the API you've designed for this tool? An example of usage
will clarify what you intend.
One technique for applying a transformation function to each record
returned by a csv DictReader:
import csv
import math
from io import StringIO
f = StringIO('''\
a,b,c
1,2,3
4,5,6
''')
def pass_(value):
return value
transforms = {
'a': lambda v: math.sin(int(v)),
'b': lambda v: math.cos(int(v)),
}
for row in csv.DictReader(f):
print({k: transforms.get(k, pass_)(v) for k, v in row.items()})
Using __missing__ for your transform dict might be more elegant than .get
with a pass_ as default.
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