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How can I combine two HashMap objects containing the same types?
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One-liner using Java 8 Stream API:
map3 = Stream.of(map1, map2).flatMap(m -> m.entrySet().stream())
.collect(Collectors.toMap(Entry::getKey, Entry::getValue))
Among the benefits of this method is ability to pass a merge function, which will d...
SQL to determine minimum sequential days of access?
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@Artem: That was what I initially thought but when I thought about it, if you have an index on (UserId, CreationDate), the records will show up consecutively in the index and it should perform well.
– Mehrdad Afshari
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How to print a dictionary line by line in Python?
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Hmm. I think my problem is even worse than that. Basically I've parsed out some data from an HTML table, and I happened to store it in a dictionary, and now I'm trying to take that dictionary data and put it into a DataFrame before I export it all to an Oracle table....it's pret...
What is a proper naming convention for MySQL FKs?
...constraints. If a name is not given, InnoDB creates a unique name automatically.
In any case, this is the convention that I use:
fk_[referencing table name]_[referenced table name]_[referencing field name]
Example:
CREATE TABLE users(
user_id int,
name varchar(100)
);
CREATE T...
How to turn on/off ReactJS 'development mode'?
...me helpers off during production. Just using the minified react will leave all those potential optimizations on the table as well.
Ultimately the magic comes down to React embedding references to process.env.NODE_ENV throughout the codebase; these act like a feature toggle.
if (process.env.NODE_ENV ...
How do I send an HTML email?
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@FizerKhan - really? docs.oracle.com/javaee/6/api/javax/mail/internet/…
– Nick Grealy
Mar 31 '15 at 3:49
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Macro vs Function in C
...uct webpage page;
page.numButtons = 2;
num_button_holes(page) -> 8
Finally, macros can be difficult to debug, producing weird syntax errors or runtime errors that you have to expand to understand (e.g. with gcc -E), because debuggers cannot step through macros, as in this example:
#define prin...
Preloading images with JavaScript
Is the function I wrote below enough to preload images in most, if not all, browsers commonly used today?
14 Answers
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How are 3D games so efficient? [closed]
...dware.
For instance, one easy optimization you can make involves not actually trying to draw things that can't be seen. Consider a complex scene like a cityscape from Grand Theft Auto IV. The renderer isn't actually rendering all of the buildings and structures. Instead, it's rendering only what t...
Dealing with commas in a CSV file
...any easily-available csv library - that is to say RFC 4180.
There's actually a spec for CSV format and how to handle commas:
Fields containing line breaks (CRLF), double quotes, and commas should be enclosed in double-quotes.
http://tools.ietf.org/html/rfc4180
So, to have values foo and ...