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How to check if a map contains a key in Go?
...thout worrying about the actual
value, you can use the blank identifier (_) in place of the usual
variable for the value.
_, present := timeZone[tz]
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Pandas percentage of total with groupby
...you can calculate the percentage in a simpler way -- just groupby the state_office and divide the sales column by its sum. Copying the beginning of Paul H's answer:
# From Paul H
import numpy as np
import pandas as pd
np.random.seed(0)
df = pd.DataFrame({'state': ['CA', 'WA', 'CO', 'AZ'] * 3,
...
Understanding the difference between Object.create() and new SomeFunction()
... difference is in step 3)
new Test():
create new Object() obj
set obj.__proto__ to Test.prototype
return Test.call(obj) || obj;
// normally obj is returned but constructors in JS can return a value
Object.create( Test.prototype )
create new Object() obj
set obj.__proto__ to Test.prototype...
Can I implement an autonomous `self` member type in C++?
...,Ts...> : public Ts...
{
protected:
typedef X self;
};
#define WITH_SELF(X) X : public Self<X>
#define WITH_SELF_DERIVED(X,...) X : public Self<X,__VA_ARGS__>
class WITH_SELF(Foo)
{
void test()
{
self foo;
}
};
If you want to derive from Foo then you should...
Why does GCC generate such radically different assembly for nearly the same C code?
... why they are so different, first we must understand how GCC optimizes fast_trunc_one().
Believe it or not, fast_trunc_one() is being optimized to this:
int fast_trunc_one(int i) {
int mantissa, exponent;
mantissa = (i & 0x07fffff) | 0x800000;
exponent = 150 - ((i >> 23) &...
How to change field name in Django REST Framework
...erializerMethodField:
Here is the model Park, which has name and alternate_name fields.
class Park(models.Model):
name = models.CharField(max_length=256)
alternate_name = models.CharField(max_length=256, blank=True)
objects = models.GeoManager()
class Meta:
db_table = u'...
How can I cast int to enum?
...ags or enum values
.field public specialname rtspecialname int32 value__
}
What should get your attention here is that the value__ is stored separately from the enum values. In the case of the enum Foo above, the type of value__ is int16. This basically means that you can store whatever you w...
Iterate over the lines of a string
...< 0: break
yield foo[prevnl + 1:nextnl]
prevnl = nextnl
if __name__ == '__main__':
for f in f1, f2, f3:
print list(f())
Running this as the main script confirms the three functions are equivalent. With timeit (and a * 100 for foo to get substantial strings for more precise me...
Cannot delete or update a parent row: a foreign key constraint fails
...references. This:
ALTER TABLE `advertisers`
ADD CONSTRAINT `advertisers_ibfk_1` FOREIGN KEY (`advertiser_id`)
REFERENCES `jobs` (`advertiser_id`);
...is actually the opposite to what it should be. As it is, it means that you'd have to have a record in the jobs table before the advertis...
MongoDB/Mongoose querying at a specific date?
...l moments in a day.
db.posts.find( //query today up to tonight
{"created_on": {"$gte": new Date(2012, 7, 14), "$lt": new Date(2012, 7, 15)}})
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