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What is a “symbol” in Julia?
...cally:
I am trying to use Julia's DataFrames package, specifically the readtable() function with the names option, but that requires a vector of symbols.
...
Remove NA values from a vector
...idiom instead:
d <- d[!is.na(d)]
A final note: Other functions (e.g. table(), lm(), and sort()) have NA-related arguments that use different names (and offer different options). So if NA's cause you problems in a function call, it's worth checking for a built-in solution among the function's a...
Why is [1,2] + [3,4] = “1,23,4” in JavaScript?
...umber, evaluating o + '2' produces '42', a string.
To see how the overview table was generated visit http://jsfiddle.net/1obxuc7m/
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How to fix the uninitialized constant Rake::DSL problem on Heroku?
...he setup for it, otherwise Heroku complains about the missing delayed_jobs table:
#add to gemfile
gem 'delayed_job'
#at command line
bundle install
rails g delayed_job
rake db:migrate
git add -A
git commit -a -m "added delayed_job gem"
git push
heroku rake db:migrate --app myapp
heroku restart --a...
Mac OS X Terminal: Map option+delete to “backward delete word”
...
See http://www.bigsmoke.us/readline/shortcuts for a nice little reference table.
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Equals(=) vs. LIKE
...rmance:
A personal example using mysql 5.5: I had an inner join between 2 tables, one of 3 million rows and one of 10 thousand rows.
When using a like on an index as below(no wildcards), it took about 30 seconds:
where login like '12345678'
using 'explain' I get:
When using an '=' on the s...
Unique BooleanField value in Django?
...d that some of them address the same issue successfully and each one is suitable in different situations:
I would choose:
@semente: Respects the constraint at the database, model and admin form levels while it overrides Django ORM the least possible. Moreover it can probably be used inside a thr...
Why does C++11 not support designated initializer lists as C99? [closed]
...me it has failed
Ben Voigt's comments have helped me to see the insurmountable problems with this approach; given:
struct X {
int c;
char a;
float b;
};
What order would these functions be called in in c99: struct X foo = {.a = (char)f(), .b = g(), .c = h()}? Surprisingly, in c99:
...
Why is it not advisable to have the database and web server on the same machine?
...ver will cause downtime all by itself. Enough privileges to add records to tables is enough to render a site useless.
– Daniel Earwicker
Mar 19 '09 at 0:04
PHP: Storing 'objects' inside the $_SESSION
... it on every request. Then the server uses that ID as a key into a big hashtable of Session objects. Whenever the server gets a request, it looks up the Session info out of its hashtable of session objects based on the ID the client submitted with the request. All this extra work is a double whammy ...