Getting values from Json data in Python - json

Question

I have a json file that I am trying to pull specific attribute data from. The Json data is essentially a dictionary. Before the data is turned into a file, it is first held in a variable like this:
params = {'f': 'json', 'where': '1=1', 'geometryType': 'esriGeometryPolygon', 'spatialRel': 'esriSpatialRelIntersects','outFields': '*', 'returnGeometry': 'true'}
r = requests.get('https://hazards.fema.gov/gis/nfhl/rest/services/CSLF/Prelim_CSLF/MapServer/3/query', params)
cslfJson = r.json()
and then written into a file like this:
path = r"C:/Workspace/Sandbox/ScratchTests/cslf.json"
with open(path, 'w') as f:
json.dump(cslfJson, f, indent=2)
within this json data is an attribute called DFIRM_ID. I want to create an empty list called dfirm_id = [], get all of the values for DFIRM_ID and for that value, append it to the list like this dfirm_id.append(value). I am thinking I need to somehow read through the json variable data or the actual file, but I am not sure how to do it. Any suggestions on an easy method to accomplish this?
dfirm_id = []
for k, v in cslf:
if cslf[k] == 'DFIRM_ID':
dfirm.append(cslf[v])
As requested, here is what print(cslfJson) looks like:
It actually prints a huge dictionary that looks like this:
{'displayFieldName': 'CSLF_ID', 'fieldAliases': {'OBJECTID':
'OBJECTID', 'CSLF_ID': 'CSLF_ID', 'Area_SF': 'Area_SF', 'Pre_Zone':
'Pre_Zone', 'Pre_ZoneST': 'Pre_ZoneST', 'PRE_SRCCIT': 'PRE_SRCCIT',
'NEW_ZONE': 'NEW_ZONE', 'NEW_ZONEST': .... {'attributes': {'OBJECTID':
26, 'CSLF_ID': '13245C_26', 'Area_SF': 5.855231804165408e-05,
'Pre_Zone': 'X', 'Pre_ZoneST': '0.2 PCT ANNUAL CHANCE FLOOD HAZARD',
'PRE_SRCCIT': '13245C_STUDY1', 'NEW_ZONE': 'A', 'NEW_ZONEST': None,
'NEW_SRCCIT': '13245C_STUDY2', 'CHHACHG': 'None (Zero)', 'SFHACHG':
'Increase', 'FLDWYCHG': 'None (Zero)', 'NONSFHACHG': 'Decrease',
'STRUCTURES': None, 'POPULATION': None, 'HUC8_CODE': None, 'CASE_NO':
None, 'VERSION_ID': '2.3.3.3', 'SOURCE_CIT': '13245C_STUDY2', 'CID':
'13245C', 'Pre_BFE': -9999, 'Pre_BFE_LEN_UNIT': None, 'New_BFE':
-9999, 'New_BFE_LEN_UNIT': None, 'BFECHG': 'False', 'ZONECHG': 'True', 'ZONESTCHG': 'True', 'DFIRM_ID': '13245C', 'SHAPE_Length':
0.009178426056888393, 'SHAPE_Area': 4.711699932249018e-07, 'UID': 'f0125a91-2331-4318-9a50-d77d042a48c3'}}, {'attributes': .....}

Answer 1

If your json data is already a dictionary, then take advantage of that. The beauty of a dictionary / hashmap is that it provides an average time complexity of O(1).
Based on your comment, I believe this will solve your problem:
dfirm_id = []
for feature in cslf['features']:
dfirm_id.append(feature['attributes']['DFIRM_ID'])