大约有 24,000 项符合查询结果（耗时：0.0531秒） [XML]
“is” operator behaves unexpectedly with integers
...tively rare. Here's an example (will work in Python 2 and 3) e.g.
SENTINEL_SINGLETON = object() # this will only be created one time.
def foo(keyword_argument=None):
if keyword_argument is None:
print('no argument given to foo')
bar()
bar(keyword_argument)
bar('baz')
def b...
How to round a number to significant figures in Python
...t digit:
>>> from math import log10, floor
>>> def round_to_1(x):
... return round(x, -int(floor(log10(abs(x)))))
...
>>> round_to_1(0.0232)
0.02
>>> round_to_1(1234243)
1000000.0
>>> round_to_1(13)
10.0
>>> round_to_1(4)
4.0
>>> rou...
Writing a Python list of lists to a csv file
...s pd
In [2]: a = [[1.2,'abc',3],[1.2,'werew',4],[1.4,'qew',2]]
In [3]: my_df = pd.DataFrame(a)
In [4]: my_df.to_csv('my_csv.csv', index=False, header=False)
share
|
improve this answer
...
How do I list all tables in a schema in Oracle SQL?
...BA role.
With any of those, you can select:
SELECT DISTINCT OWNER, OBJECT_NAME
FROM DBA_OBJECTS
WHERE OBJECT_TYPE = 'TABLE'
AND OWNER = '[some other schema]'
Without those system privileges, you can only see tables you have been granted some level of access to, whether directly or through...
In MySQL queries, why use join instead of where?
...x queries can benefit from using ANSI-92 syntax:
Ability to control JOIN order - the order which tables are scanned
Ability to apply filter criteria on a table prior to joining
From a Maintenance Perspective:
There are numerous reasons to use ANSI-92 JOIN syntax over ANSI-89:
More readable...
What is the difference between Unidirectional and Bidirectional JPA and Hibernate associations?
...rectional, I think it would be better to call setGroup() from addUser() in order to hold both sides consistent.
– axtavt
Mar 19 '11 at 16:24
...
How to identify if the DLL is Debug or Release build (in .NET) [duplicate]
...wered Apr 28 '09 at 17:15
this. __curious_geekthis. __curious_geek
40.1k2020 gold badges105105 silver badges132132 bronze badges
...
How do I trim whitespace from a string?
...l-accepted and meaningful names that the vast majority of languages use in order to be "unique" and "different" - strip instead of trim, isinstance instead of instanceof, list instead of array, etc, etc. Why not just use the names everyone is familiar with?? geez :P
– Gershom
...
elasticsearch v.s. MongoDB for filtering application [closed]
...rms of which fields are used for the filtering at any moment", it could be orders of magnitude faster, especially as the datasets become larger. The difference lies in the underlying query implementations:
Elastic/Lucene use the Vector Space Model and inverted indexes for Information Retrieval, wh...
Best practices for in-app database migration for Sqlite
...t/set this variable with the following sqlite statements:
> PRAGMA user_version;
> PRAGMA user_version = 1;
When the app starts, I check the current user-version, apply any changes that are needed to bring the schema up to date, and then update the user-version. I wrap the updates in a t...