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Convert data.frame columns from factors to characters
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edited May 23 '17 at 12:18
Community♦
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answered May 17 '10 at 17:21
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How to change a nullable column to not nullable in a Rails migration?
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208
If you do it in a migration then you could probably do it like this:
# Make sure no null valu...
Are nested try/except blocks in python a good programming practice?
...") from None
PS. has_key() has been deprecated for a long time in Python 2. Use item in self.dict instead.
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How to handle initializing and rendering subviews in Backbone.js?
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260
This is a great question. Backbone is great because of the lack of assumptions it makes, but i...
Hash collision in git
...aracter times 40... 160 bits. Now we know 10 bits is approximately 1000 (1024 to be exact) meaning that there are 1 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 different SHA-1 hashes... 1048.
What is this equivalent of? Well the Moon is made up of about 1047 atoms. So if we have ...
Can Selenium interact with an existing browser session?
...ome working code which claims to support this: https://web.archive.org/web/20171214043703/http://tarunlalwani.com/post/reusing-existing-browser-session-selenium-java/.
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Create unique constraint with null columns
..., menu_id, recipe_id)
WHERE menu_id IS NOT NULL;
CREATE UNIQUE INDEX favo_2col_uni_idx ON favorites (user_id, recipe_id)
WHERE menu_id IS NULL;
This way, there can only be one combination of (user_id, recipe_id) where menu_id IS NULL, effectively implementing the desired constraint.
Possible dra...
How to change the foreign key referential action? (behavior)
...ocess:
Suppose, a table1 has a foreign key with column name fk_table2_id, with constraint name fk_name and table2 is referred table with key t2 (something like below in my diagram).
table1 [ fk_table2_id ] --> table2 [t2]
First step, DROP old CONSTRAINT: (reference)
ALTER TABLE ...
Logging uncaught exceptions in Python
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Martin Thoma
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answered Jun 4 '11 at 3:26
JacindaJacind...