Develop Reference

Week number to week commencing date USING PYTHON?

n=10
I want to get the week commencing date of the 10th week of the current year (2022), i.e., 3/7/2022. How can this be done using datetime functions?

You need to use the %W directive, but you also need to specify what the start day is of the week and of course the year.
Example:
from datetime import datetime
print(datetime.strptime("10-2022-1", "%W-%Y-%w"))
Result:
2022-03-07 00:00:00
10 is the week number
2022 is the year
1 is the day of the week to start with (Monday) in order to get an actual date.
Datetime formats: https://docs.python.org/3/library/datetime.html#strftime-and-strptime-format-codes

Python: get first date of the week from calender week and year (working for 2020 but not for 2021)

I would like to extract the first date of the week from the year and the calender week (in Europe where the first calender week is the week that includes the 4th of January)
My code works correctly for
import datetime
year=20
week=53
print(datetime.datetime.strptime(str(year) + "-"+ str(week-1) +'-1-CET', "%y-%U-%w-%Z"))
the output is 2020-12-28 00:00:00 which is correct
for
import datetime
year=21
week=1
print(datetime.datetime.strptime(str(year) + "-"+ str(week-1) +'-1-CET', "%y-%U-%w-%Z"))
I get also 2020-12-28 00:00:00.The correct output would be 2021-01-04.
Could you please tell me where my mistake is?
Thanks

Using %V instead of %U should make things easier.

Unable to parse an exact result from a webpage using requests

I've created a script in python to parse two fields from a webpage - total revenue and it's concerning date. The fields I'm after are javascript encrypted. They are available in page source within json array. The following script can parse those two fields accordingly.
However, the problem is the date visible in that page is different from the one available in page source.
Webpage link
The date in that webpage is like this
The date in page source is like this
There is clearly a variation of one day.
After visiting that webpage when you click on this tab Quarterly you can see the results there:
I've tried with:
import re
import json
import requests
url = 'https://finance.yahoo.com/quote/GTX/financials?p=GTX'
res = requests.get(url)
data = re.findall(r'root.App.main[^{]+(.*);',res.text)[0]
jsoncontent = json.loads(data)
container = jsoncontent['context']['dispatcher']['stores']['QuoteSummaryStore']['incomeStatementHistoryQuarterly']['incomeStatementHistory']
total_revenue = container[0]['totalRevenue']['raw']
concerning_date = container[0]['endDate']['fmt']
print(total_revenue,concerning_date)
Result I get (revenue in million):
802000000 2019-06-30
Result I wish to get:
802000000 2019-06-29
When I try with this ticker AAPL, I get the exact date, so subtracing or adding a day is not an option.
How can I get the exact date from that site?
Btw, I know how to get them using selenium, so I would only like to stick to requests.

As mentioned in the comments, you need to convert the date to the appropriate timezone (EST), which can be done with datetime and dateutil.
Here is a working example:
import re
import json
import requests
from datetime import datetime, timezone
from dateutil import tz
url = 'https://finance.yahoo.com/quote/GTX/financials?p=GTX'
res = requests.get(url)
data = re.findall(r'root.App.main[^{]+(.*);',res.text)[0]
jsoncontent = json.loads(data)
container = jsoncontent['context']['dispatcher']['stores']['QuoteSummaryStore']['incomeStatementHistoryQuarterly']['incomeStatementHistory']
total_revenue = container[0]['totalRevenue']['raw']
EST = tz.gettz('EST')
raw_date = datetime.fromtimestamp(container[0]['endDate']['raw'], tz=EST)
concerning_date = raw_date.date().strftime('%d-%m-%Y')
print(total_revenue, concerning_date)

The updated section of this answer outlines the root cause of the date differences.
ORIGINAL ANSWER
Some of the raw values in your JSON are UNIX timestamps.
Reference from your code with modifications:
concerning_date_fmt = container[0]['endDate']['fmt']
concerning_date_raw = container[0]['endDate']['raw']
print(f'{concerning_date} -- {concerning_date_raw}')
# output
2019-07-28 -- 1564272000
'endDate': {'fmt': '2019-07-28', 'raw': 1564272000}
1564272000 is the number of elapsed seconds since January 01 1970. This date was the start of the Unix Epoch and the time is in Coordinated Universal Time (UTC). 1564272000 is the equivalent to: 07/28/2019 12:00am (UTC).
You can covert these timestamps to a standard datetime format by using built-in Python functions
from datetime import datetime
unix_timestamp = int('1548547200')
converted_timestamp = datetime.utcfromtimestamp(unix_timestamp).strftime('%Y-%m-%dT%H:%M:%SZ')
print (converted_timestamp)
# output Coordinated Universal Time (or UTC)
2019-07-28T00:00:00Z
reformatted_timestamp = datetime.strptime(converted_timestamp, '%Y-%m-%dT%H:%M:%SZ').strftime('%d-%m-%Y')
print (reformatted_timestamp)
# output
28-07-2019
This still does not solve your original problem related to JSON dates and column dates being different at times. But here is my current hypothesis related to the date disparities that are occurring.
The json date (fmt and raw) that are being extracted from root.App.main are in Coordinated Universal Time (UTC). This is clear because of the UNIX timestamp in raw.
The dates being displayed in the table columns seem to be in the Eastern Standard Time (EST) timezone. EST is currently UTC-4. Which means that 2019-07-28 22:00 (10pm) EST would be 2019-07-29 02:00 (2am) UTC. The server hosting finance.yahoo.com looks to be in the United States, based on the traceroute
results. These values are also in the json file:
'exchangeTimezoneName': 'America/New_York'
'exchangeTimezoneShortName': 'EDT'
There is also the possibility that some of the date differences are linked to the underlying React code, which the site uses. This issue is harder to diagnose, because the code isn't visible.
At this time I believe that the best solution would be to use the UNIX timestamp as your ground truth time reference. This reference could be used to replace the table column's date.
There is definitely some type of conversion happening between the JSON file and the columns.
NVIDIA JSON FILE: 'endDate': {'raw': 1561766400, 'fmt': '2019-06-29'}
NVIDIA Associated Total Revenue column: 6/30/2019
BUT the Total Revenue column date should be 6/28/2019 (EDT), because the UNIX time stamp for 1561766400 is 06/29/2019 12:00am (UTC).
The disparity with DELL is greater than a basic UNIX timestamp and a EDT timestamp conversion.
DELL JSON FILE:{"raw":1564704000,"fmt":"2019-08-02"}
DELL Associated Total Revenue column: 7/31/2019
If we convert the UNIX timestamp to an EDT timestamp, the result would be 8/1/2019, but that is not the case in the DELL example, which is 7/31/2019. Something within the Yahoo code base has to be causing this difference.
I'm starting to believe that React might be the culprit with these date differences, but I cannot be sure without doing more research.
If React is the root cause then the best option would be to use the date elements from the JSON data.
UPDATED ANSWER 10-17-2019
This problem is very interesting, because it seems that these column dates are linked to a company's official end of fiscal quarter and not a date conversation issue.
Here are several examples for
Apple Inc. (AAPL)
Atlassian Corporation Plc (TEAM)
Arrowhead Pharmaceuticals, Inc. (ARWR):
Their column dates are:
6/30/2019
3/31/2019
12/31/2018
9/30/2018
These dates match to these fiscal quarters.
Quarter 1 (Q1): January 1 - March 31.
Quarter 2 (Q2): April 1 - June 30.
Quarter 3 (Q3): July 1 - September 30.
Quarter 4 (Q4): October 1 - December 31
These fiscal quarter end dates can vary greatly as this DELL example shows.
DELL (posted in NASDAQ)
End of fiscal quarter: July 2019
Yahoo Finance
Column date: 7/31/2019
JSON date: 2019-08-02
From the company's website:
When does Dell Technologies’ fiscal year end?
Our fiscal year is the 52- or 53-week period ending on the Friday nearest January 31. Our 2020 fiscal year will end on January 31, 2020. For prior fiscal years, see list below: Our 2019 fiscal year ended on February 1, 2019 Our 2018 fiscal year ended on February 2, 2018 Our 2017 fiscal year ended on February 3, 2017 Our 2016 fiscal year ended on January 29, 2016 Our 2015 fiscal year ended on January 30, 2015 Our 2014 fiscal year ended on January 31, 2014 Our 2013 fiscal year ended on February 1, 2013
NOTE: The 05-03-19 and 08-02-19 dates.
These are from the JSON quarter data for DELL:
{'raw': 1564704000, 'fmt': '2019-08-02'}
{'raw': 1556841600, 'fmt': '2019-05-03'}
It seems that these column dates are linked to a company's fiscal quarter end dates. So I would recommend that you either use the JSON date as you primary reference element or the corresponding column date.
P.S. There is some type of date voodoo occurring at Yahoo, because they seem to move these column quarter dates based on holidays, weekends and end of month.

Instead of getting the fmt of the concerning_date, It's better to get the timestamp.
concerning_date = container[0]['endDate']['raw']
In the example above you will get the result 1561852800 which you can transfer into a date with a certain timezone. (Hint: use datetime and pytz). This timestamp will yield the following results based on timezone:
Date in Los Angeles*: 29/06/2019, 17:00:00
Date in Berlin* :30/06/2019, 02:00:00
Date in Beijing*: 30/06/2019, 07:00:00
Date in New York* :29/06/2019, 19:00:00

Calendar in python/django

I am working on a website with weekly votations, but only the first three weeks of the month, so in each instance I have a start_date and end_date field.
I'd like to know if there's a way to automitically create these instances based on the current date, for instance:
Today it is 6 of March, and votations end tomorrow, so a function should be run (tmrw) that, taking into account this month calendar, would fill in the appropiate dates for the next votations. What calendar do you recommend me, and how shoul I do it?
(Never mind the automatically run part, I'll go with celery).
Thanks!

I am not sure what your problem is and I don't know what votations are. But as a general direction of thinking: there is timeboard library that can generate rule-based schedules (calendars) and do calculations over them (DISCLAIMER: I am the author).
The code below designates, for every month of 2018, the days of the first three weeks of the month as 'on-duty' (i.e. 'active', 'usable') and the rest as 'off-duty':
>>> import timeboard as tb
>>> weekly = tb.Organizer(marker='W', structure=[[1],[1],[1],[0],[0],[0]])
>>> monthly = tb.Organizer(marker='M', structure=[weekly])
>>> clnd = tb.Timeboard(base_unit_freq='D',
... start='01 Jan 2018', end='31 Dec 2018',
... layout=monthly)
For example, in March 2018, the days from Thursday, 1st, through Sunday, 18th, are marked 'on-duty', and the days 19-31 are marked 'off-duty'.
Now you can move along the calendar picking only on-duty days. For example, adding 1 to March, 17 gives you March 18:
>>> (clnd('17 Mar 2018') + 1).to_timestamp()
Timestamp('2018-03-18 00:00:00')
However, adding 2 carries you over to April 1, as March 19 is NOT within the first 3 weeks of March:
>>> (clnd('17 Mar 2018') + 2).to_timestamp()
Timestamp('2018-04-01 00:00:00')

Go to december month on Python

I'm trying to go back December month but my results are month 0 instead of month 12... how can I do that?
I create a code and on it I need the Today date and also the last day of the before month, I mean:
for example today is 25/01/2018 and I need 31/12/2017. On February I'm going to run it again and I need for example 25/02/2018 and 31/01/2018. That is the relationship I'm looking for
import datetime
fecha17 = time.strftime(str((int(time.strftime("%d")))-1) +"/" + str((int(time.strftime("%m")))-1) + "/%Y")