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Python list of dictionaries search
...random import randint
from timeit import timeit
list_dicts = []
for _ in range(1000): # number of dicts in the list
dict_tmp = {}
for i in range(10): # number of keys for each dict
dict_tmp[f"key{i}"] = randint(0,50)
list_dicts.append( dict_tmp )
def a():
# normal ...
How do you convert a byte array to a hexadecimal string, and vice versa?
...
}
}
return result;
}
static uint[] _Lookup32 = Enumerable.Range(0, 255).Select(i => {
string s = i.ToString("X2");
return ((uint)s[0]) + ((uint)s[1] << 16);
}).ToArray();
static string ByteArrayToHexViaLookupPerByte(byte[] bytes) {
var result = new char[bytes.Le...
Add column with constant value to pandas dataframe [duplicate]
...nment is broadcasted by pandas for each row.
df = pd.DataFrame('x', index=range(4), columns=list('ABC'))
df
A B C
0 x x x
1 x x x
2 x x x
3 x x x
df['new'] = 'y'
# Same as,
# df.loc[:, 'new'] = 'y'
df
A B C new
0 x x x y
1 x x x y
2 x x x y
3 x x x y
...
Should I use the datetime or timestamp data type in MySQL?
...in time I talk about. (See Nir's excellent answer below). [Downside: valid range].
– MattBianco
Sep 1 '10 at 14:36
123
...
What does the “at” (@) symbol do in Python?
...lf, B):
A = self
return Mat([[sum(A[i][k]*B[k][j] for k in range(len(B)))
for j in range(len(B[0])) ] for i in range(len(A))])
A = Mat([[1,3],[7,5]])
B = Mat([[6,8],[4,2]])
print(A @ B)
This code yields:
[[18, 14], [62, 66]]
...
What's the main difference between int.Parse() and Convert.ToInt32
...
int.Parse(string s)
Integer in RANGE > returns integer value
Null value > ArguementNullException
Not in format > FormatException
Value not in RANGE > OverflowException
...
Slicing of a NumPy 2d array, or how do I extract an mxm submatrix from an nxn array (n>m)?
...every other column, then you can do it with basic slicing:
In [49]: x=np.arange(16).reshape((4,4))
In [50]: x[1:4:2,1:4:2]
Out[50]:
array([[ 5, 7],
[13, 15]])
This returns a view, not a copy of your array.
In [51]: y=x[1:4:2,1:4:2]
In [52]: y[0,0]=100
In [53]: x # <---- Notice x[...
What's the difference between utf8_general_ci and utf8_unicode_ci?
...les for universal sorting and comparison, which sorts accurately in a wide range of languages.
utf8mb4_general_ci is a simplified set of sorting rules which aims to do as well as it can while taking many short-cuts designed to improve speed. It does not follow the Unicode rules and will result in ...
Hash Map in Python
...class HashMap:
def __init__(self):
self.store = [None for _ in range(16)]
def get(self, key):
index = hash(key) & 15
if self.store[index] is None:
return None
n = self.store[index]
while True:
if n.key == key:
...
A fast method to round a double to a 32-bit int explained
... 2^51 + 2^52; adding such a number forces the double to go into the "sweet range" between 2^52 and 2^53, which, as explained by Wikipedia here, has an interesting property:
Between 252=4,503,599,627,370,496 and 253=9,007,199,254,740,992 the representable numbers are exactly the integers
This f...