I am trying to create a date of readmission variable when there are type changes and transfers within admission episodes.
Using the lead(episode_start_date) function works for patients who are not transferred/have a type change. But it incorrectly picks up the episode_start_date of the next episode within the stay sequence if patients have for example a transfer.
I need to write a mutate function to pick up the episode_start_date of the admission date in the next stay sequence.
E.g. mutate(readmit_date = lead(episode_start_date) IF it is the next stay_seq (stay_seq + 1)
Related
I have a process that generates a new record every 10 minutes. It was great for some time, however, now Datum.all returns 30k+ records, which are unnecessary as the purpose is simply to display them on a chart.
So as a simple solution, I'd like to provide all available data generated in the past 24 hours, but low res data (every 100th record) prior to the last 24 hours (right back to the beginning of the dataset).
I suspect the solution is some combination of this answer which selects every nth record (but was provided in 2010), and this answer which combines two ActiveRecord objects
But I cannot work out how to get a working implementation that obtains all the required data into one instance variable
You can use OR query:
Datum.where("created_at>?", 1.day.ago).or(Datum.where("id%100=0"))
I have an InfluxDB measurement which includes a field that holds either 0 or 1.
How do I find the longest unbroken run of a given value?
Imagine that the field represents whether the sun is up or not, and I have a year's worth of data. I would like the query which finds the longest unbroken run of 1's, which would represent the longest day of the year and return me something like "23rd June 5am to 23rd June 9pm". (I'm in the northern hemisphere, and totally made those times up, but hopefully you get the idea.)
I don't think this can be done with InfluxQL. In many RDBMS, it's possible to do similar operations in a single SQL query using window functions and grouping.
I've experimented a few ways, but as of v1.3 I believe InfluxQL is just not expressive enough for this task. Limitations include:
No window functions (although some functions exhibit similar behaviour, e.g. DIFFERENCE, DERIVATIVE).
time cannot be manipulated like an ordinary tag or field value. For example, it's not possible to take the FIRST(time) of a group of measurements.
Can only GROUP BY time or tag, not by field value (or derived value from a subquery result). Additionally, when grouped by time, only group interval timestamps are returned by selector functions.
Can only ORDER BY time.
The best way to do this is therefore at the application level.
Edit: for the record, the closest I can get is to use ELAPSED to find the longest gap(s) between subsequent 0 values. This might work for you if your data model is a specific shape and data comes in at regular intervals:
SELECT TOP(elapsed, N) AS elapsed FROM (SELECT ELAPSED(field) FROM measurement WHERE field != 1)
Returns e.g. for N = 1:
time elapsed
---- -------
2000 500
However, there is no guarantee that there is a value of 1 in the gap. Use FIRST to retrieve the first measurement with field == 1 within the gap, or nothing if there are none:
SELECT FIRST(field) FROM measurement WHERE field = 1 AND time < 2000 and time > (2000 - 500)
Returns e.g.:
time first
---- -----
1000 1
Therefore the longest run of 1 values is from 1000 -> 2000.
is there a way to query for next 5 instances of given series? I am querying using time-frame:
1. ask for all the meetings for next 7 days for all user events
2. Go over each event fetched and check if event has masterSerieId
3. Return matching instances.
This feels (and is) a bit painful.
Can i request next X instances of master series right away? I can't just simply or 'simply' get them based on recurrence rule, as some might have expired.
I could image I could ask for a year ahead and pass as a query parameter masterSeriesId and limit output with $top. Is that right approach?
Based on this document, you could call /events//instances – given a start time, returns all instances in the requested time frame of the meeting specified by the provided series master ID
I am having a relational source having 60 records in it.
I want to run a workflow for this mapping, for the first time it should load only 20(1-20) records , 2nd time remaining 20(21-30) records, 3rd time remaining 20(31-60) records to a single source.
how can we do this?
One solution would be to:
use a mapping variable eg. $$rowAmount with initial value of 20
add a Sequence to generate row numbers
use a Filter with a condition RowId>$$rowAmount-20 AND RowId<$$rowAmount
use SETVARIABLE function to increase $$rowAmount by 20 and store in repository
I'm new to Ruby/Rails, so this is possibly (hopefully) a simple question that I just dont know the answer to.
I am implementing an accounting/billing system in Rails, and I'm trying to keep track of the running balance after each transaction in order to display it in the view as below:
Date Description Charges($) Credits($) Balance($)
Mar 2 Activity C $4.00 -$7.50
Feb 25 Payment for Jan $8.00 -$3.50
Feb 23 Activity B $1.50 -$11.50
Feb 20 Activity A $2.00 -$10.00
Each transaction (also known as line item) is stored in the database, with all the values above (Date, Description, Amount) except for the Balance. I can't store the balance for each transaction in the database because it may change if something happens to an earlier transaction (a payment that was posted subsequently failed later for example). So I need to calculate it on the fly for each line item, and the value for the Balance for a line item depends on the value for the line item before it (Balance = Balance of Prev Line Item + Amount for this Line Item, i.e.)
So here's my question. My current (inept) way of doing it is that in my LineItem model, I have a balance method which looks like :
def balance
prev_balance = 0
#get previous line items balance if it exists.
last_line_item = Billing::LineItem.get_last_line_item_for_a_ledger(self.issue_date,self.ledger_item_id)
if last_line_item
prev_balance = last_line_item.balance
.. some other stuff...
end
prev_balance + (-1*net_amount) # net_amount is the amount for the current line item
end
This is super costly and my view takes forever to load since I'm calculating the prev line item's balance again and again and again. Whats a better way to do this?
You're basically paying a price for not wanting to store the balance in each transaction. You could optimize your database with indices and use caches etc; but fundamentally you'll run into the problem that calculating a balance will take a long time, if you have lots of transactions.
Keep in mind that you'll continue to get new transactions, and your problem will thus get worse over time.
You could consider several design alternatives. First, like Douglas Lise mentioned, you could store the balance in each transaction. If an earlier dated transaction comes in, it means you may have to do an update of several transaction since that date. However, this has an upper-bound (depending on how "old" transactions you want to allow), so it has a reasonable worst-case behavior.
Alternatively, you can do a reconciliation step. Every month you "close the books" on transactions older than X weeks. After reconciliation you store the Balance you calculated. In def balance you now use your existing logic, but also refer to "balance as of the previous reconciliation". This again, provides a reasonable and predictable worst-case scenario.