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How to make MySQL handle UTF-8 properly
... answer - You should almost always be using the utf8mb4 charset and utf8mb4_unicode_ci collation.
To alter database:
ALTER DATABASE dbname CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
See:
Aaron's comment on this answer How to make MySQL handle UTF-8 properly
What's the difference betwee...
Django templates: verbose version of a choice
...
In Django templates you can use the "get_FOO_display()" method, that will return the readable alias for the field, where 'FOO' is the name of the field.
Note: in case the standard FormPreview templates are not using it, then you can always provide your own templat...
What is a plain English explanation of “Big O” notation?
...
-1: This is blatantly wrong: _"BigOh is relative representation of complexity of algorithm". No. BigOh is an asymptotic upper bound and exists quite well independent of computer science. O(n) is linear. No, you are confusing BigOh with theta. log n is O(...
Select random lines from a file
...
@J.F.Sebastian The code: sort -R input | head -n <num_lines>. The input file was 279GB, with 2bi+ lines. Can't share it, though. Anyway, the point is you can keep some lines in memory with shuffle to do the random selection of what to output. Sort is going to sort the entire...
Number of elements in a javascript object
...et it.
In the past, Mozilla's Javascript variant exposed the non-standard __count__, but it has been removed with version 1.8.5.
For cross-browser scripting you're stuck with explicitly iterating over the properties and checking hasOwnProperty():
function countProperties(obj) {
var count = 0;...
Can you find all classes in a package using reflection?
...0, file.getName().length() - 6)));
}
}
return classes;
}
__________
1 This method was taken originally from http://snippets.dzone.com/posts/show/4831, which was archived by the Internet Archive, as linked to now. The snippet is also available at https://dzone.com/articles/get-all-c...
How do you query for “is not null” in Mongo?
...
db.collection_name.find({"filed_name":{$exists:true}});
fetch documents that contain this filed_name even it is null.
My proposition:
db.collection_name.find({"field_name":{$type:2}}) //type:2 == String
You can check on the required...
adding noise to a signal in python
...umpy as np
import matplotlib.pyplot as plt
t = np.linspace(1, 100, 1000)
x_volts = 10*np.sin(t/(2*np.pi))
plt.subplot(3,1,1)
plt.plot(t, x_volts)
plt.title('Signal')
plt.ylabel('Voltage (V)')
plt.xlabel('Time (s)')
plt.show()
x_watts = x_volts ** 2
plt.subplot(3,1,2)
plt.plot(t, x_watts)
plt.title...
Python extract pattern matches
... (.*) is valid")
>>> result = p.search(s)
>>> result
<_sre.SRE_Match object at 0x10555e738>
>>> result.group(1) # group(1) will return the 1st capture (stuff within the brackets).
# group(0) will returned the entire matched text.
'my_user_...
Compile time string hashing
...the code snippet:
// CRC32 Table (zlib polynomial)
static constexpr uint32_t crc_table[256] = {
0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d0...