Combining Code Steps into a User-Defined Function - python
I'm writing a function that retrieves data from an API based on an ID#, then reads the json response into a pandas dataframe, munges the dataframe, and finally compiles every dataframe together. The goal is to pass a pandas series of ID#'s into the function, to retrieve the relevant data for a list of thousands of IDs.
When I execute every step manually, the steps work. I get a nice one-row pandas dataframe with all of the columns and the values that I want. When I combine all of the steps within a function containing a for-loop, it stops working.
Here are the steps:
req = Request('https://gs-api.greatschools.org/schools/3601714/metrics') ##request
req.add_header('X-API-Key', 'XXXXXXXXXXXXXXXXXXXXXXX') ##authenticate
content = urlopen(req).read() ##retrieve
data = pd.read_json(content) ##convert json to pandas dataframe
data.reset_index(inplace=True) ##reset index
data['id'] = 3601714 ##add id column
data.drop(columns=['head-official-name','head-official-email'],inplace=True) ##drop columns
data.pivot(['enrollment',
'percent-free-and-reduced-price-lunch',
'percent-students-with-limited-english-proficiency',
'student-teacher-ratio',
'percentage-male',
'percentage-female',
'percentage-of-teachers-with-3-or-more-years-experience',
'percentage-of-full-time-teachers-who-are-certified',
'average-salary','id'], 'index', 'ethnicity') ##pivot the dataframe
I've combined all of these steps into a function:
def demographics(universal_id):
demo_mstr = []
for item in universal_id:
id = item
req = Request(f'https://gs-api.greatschools.org/schools/{id}/metrics')
req.add_header('X-API-Key', 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX')
content = urlopen(req).read()
data = pd.read_json(content)
data.reset_index(inplace=True)
data['id'] = id
data.drop(columns=['head-official-name','head-official-email'],inplace=True)
data = data.pivot(['enrollment',
'percent-free-and-reduced-price-lunch',
'percent-students-with-limited-english-proficiency',
'student-teacher-ratio',
'percentage-male',
'percentage-female',
'percentage-of-teachers-with-3-or-more-years-experience',
'percentage-of-full-time-teachers-who-are-certified',
'average-salary','id'], 'index', 'ethnicity')
demo_mstr.append(data)
return demo_mstr
If I run the function on a test list of ID#s, I get the following error: HTTPError: HTTP Error 422:
I've rewritten the function a number of times, and I've managed to get different error types, but not a working function.
What am I missing?
Update: I am answering my own question, in the hopes that it helps someone.
So, I figured out that the 422 error was related to the fact that not every ID# had the data associated with it, in the API. Hence, some of the API calls were returning no data, which caused the error.
As for pivot, I realized that the need for pivot was caused by pandas' poor handling of json data. In my mind, pd.read_json is only good for exploratory analysis, and even then, it's kind of useless.
What you should do instead is use r.json() to unpack your raw json into its constituent dictionaries, and you need to write a parse_json function that iterates over the dictionaries, and converts them into the column names you desire.
Converting first to a pandas dataframe, then pivoting, then trying to append dataframes together is a recipe for disaster. Stay in json, do what you need to do with json, append all the json arrays into a master list, and then only convert to pandas dataframe at the very end!
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