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Regex to validate date format dd/mm/yyyy
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20 Answers
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How can I multiply and divide using only bit shifting and adding?
...fting you want to decompose one of the numbers by powers of two, like so:
21 * 5 = 10101_2 * 101_2 (Initial step)
= 10101_2 * (1 * 2^2 + 0 * 2^1 + 1 * 2^0)
= 10101_2 * 2^2 + 10101_2 * 2^0
= 10101_2 << 2 + 10101_2 << 0 (Decomposed)
= 10101_2 *...
Mean per group in a data.frame [duplicate]
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257
This type of operation is exactly what aggregate was designed for:
d <- read.table(text=
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What is the optimal Jewish toenail cutting algorithm?
...le. Luckily, humans only have five toes per foot*, so there are only 5! = 120 unrestricted sequences.
Python example:
#seq is only valid when consecutive elements in the list differ by at least two.
def isValid(seq):
for i in range(len(seq)-1):
a = seq[i]
b = seq[i+1]
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How is OAuth 2 different from OAuth 1?
In very simple terms, can someone explain the difference between OAuth 2 and OAuth 1?
10 Answers
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Difference between Math.Floor() and Math.Truncate()
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Mapping two integers to one, in a unique and deterministic way
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234
You're looking for a bijective NxN -> N mapping. These are used for e.g. dovetailing. Have ...
Understanding exactly when a data.table is a reference to (vs a copy of) another data.table
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Iterating over every two elements in a list
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Creating dataframe from a dictionary where entries have different lengths
...hon 3.x:
import pandas as pd
import numpy as np
d = dict( A = np.array([1,2]), B = np.array([1,2,3,4]) )
pd.DataFrame(dict([ (k,pd.Series(v)) for k,v in d.items() ]))
Out[7]:
A B
0 1 1
1 2 2
2 NaN 3
3 NaN 4
In Python 2.x:
replace d.items() with d.iteritems().
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