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SQL RANK() versus ROW_NUMBER()
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229
ROW_NUMBER : Returns a unique number for each row starting with 1. For rows that have duplicat...
How do you calculate log base 2 in Java for integers?
I use the following function to calculate log base 2 for integers:
10 Answers
10
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Write a number with two decimal places SQL server
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218
try this
SELECT CONVERT(DECIMAL(10,2),YOURCOLUMN)
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Sorting arrays in NumPy by column
...ck example, to sort it and return a copy:
In [1]: import numpy as np
In [2]: a = np.array([[1,2,3],[4,5,6],[0,0,1]])
In [3]: np.sort(a.view('i8,i8,i8'), order=['f1'], axis=0).view(np.int)
Out[3]:
array([[0, 0, 1],
[1, 2, 3],
[4, 5, 6]])
To sort it in-place:
In [6]: a.view('i8,i8...
how to check the dtype of a column in python pandas
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127
You can access the data-type of a column with dtype:
for y in agg.columns:
if(agg[y].dtype...
What do all of Scala's symbolic operators mean?
...to look for them. Or, failing that, look at the index (presently broken on 2.9.1, but available on nightly).
Every Scala code has three automatic imports:
// Not necessarily in this order
import _root_.java.lang._ // _root_ denotes an absolute path
import _root_.scala._
import _root_.scala.Pr...
How to make lists contain only distinct element in Python? [duplicate]
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278
The simplest is to convert to a set then back to a list:
my_list = list(set(my_list))
One d...
Weighted random numbers
...e items have individual weights:
1) calculate the sum of all the weights
2) pick a random number that is 0 or greater and is less than the sum of the weights
3) go through the items one at a time, subtracting their weight from your random number, until you get the item where the random number is ...