This question already has answers here:
numpy matrix vector multiplication [duplicate]
(1 answer)
What does the "at" (#) symbol do in Python?
(14 answers)
Closed 3 years ago.
I am trying to understand some code in which I found this statement. I don't know what "#" sign is doing here.
This is a running code for landmark detection, you can check full code here: https://github.com/cleardusk/3DDFA/blob/master/utils/ddfa.py
vertex = p # (u + w_shp # alpha_shp + w_exp # alpha_exp).reshape(3, -1, order='F') + offset
I believe it's used for matrix multiplication. Refer this for more: What does the "at" (#) symbol do in Python?
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This question already has answers here:
What does the ** maths operator do in Python?
(5 answers)
Closed 5 months ago.
import math
def countSquares(x):
sqrt=x**0.5
result=int(sqrt)
return result
x=81
print(countSquares(x))
x**0.5 is "x to the power of 0.5" which essentially means square root of x.
This question already has answers here:
The tilde operator in Python
(9 answers)
Closed 1 year ago.
pd_selftest = pd_selftest[pd_selftest['SICCD'] != 0]
pd_selftest = pd_selftest[~pd_selftest['SICCD'].isnull()]
I'd like to know what the function of the ~ is in the above code.
That's the bit-wise invert or not operator. So, it returns only those lines where the SICCID column is not null. I would probably use the word not in this case.
This question already has answers here:
Why is exponentiation applied right to left?
(4 answers)
Closed 2 years ago.
print (2**3**2)
Answer is 512.
Why 512 is answer not 64? Because ((2^3)^2) = 64
I want to know the inside math operation of print (2** 3**2)
The order of operations for exponentiation is right-to-left, not-left-to right. So:
2**3**2
is interpretted as:
2**(3**2) = 2**(9) = 512
This question already has answers here:
Python Perfect Square
(3 answers)
Check if a number is a perfect square
(25 answers)
Closed 5 years ago.
I wrote this alternative to finding if a number was a perfect square or no how can I fix this:
n = input ('type n ')
message = ('false')
if n>0 and (math.sqrt(n)).is_integer(): message = ('true')
print (message)
This question already has answers here:
Math operations from string [duplicate]
(8 answers)
Closed 6 years ago.
I have a string with a formula 5 - 3, and I need to get the result in integer. How could I do that?
use eval function:
eval("5 - 3") # 2
test = "5-3"
print(eval(test))
Gives 2