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Build vs new in Rails 3
In the Rails 3 docs , the build method for associations is described as being the same as the new method, but with the automatic assignment of the foreign key. Straight from the docs:
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Difference between '..' (double-dot) and '…' (triple-dot) in range generation?
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edited Dec 21 '16 at 0:33
answered Mar 13 '12 at 19:48
A...
Pandas: create two new columns in a dataframe with values calculated from a pre-existing column
... from pandas import *
In [2]: def calculate(x):
...: return x*2, x*3
...:
In [3]: df = DataFrame({'a': [1,2,3], 'b': [2,3,4]})
In [4]: df
Out[4]:
a b
0 1 2
1 2 3
2 3 4
In [5]: df["A1"], df["A2"] = zip(*df["a"].map(calculate))
In [6]: df
Out[6]:
a b A1 A2
0 1 2 2...
warning: implicit declaration of function
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236
You are using a function for which the compiler has not seen a declaration ("prototype") yet.
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How to split a sequence into two pieces by predicate?
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By using partition method:
scala> List(1,2,3,4).partition(x => x % 2 == 0)
res0: (List[Int], List[Int]) = (List(2, 4),List(1, 3))
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Emulate ggplot2 default color palette
...lt color palette for a desired number of colors. For example, an input of 3 would produce a character vector of HEX colors with these colors:
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Converting a column within pandas dataframe from int to string
...hape(5,2),columns=list('AB'))
In [17]: df
Out[17]:
A B
0 0 1
1 2 3
2 4 5
3 6 7
4 8 9
In [18]: df.dtypes
Out[18]:
A int64
B int64
dtype: object
Convert a series
In [19]: df['A'].apply(str)
Out[19]:
0 0
1 2
2 4
3 6
4 8
Name: A, dtype: object
In [20]: df['A...
Why declare unicode by string in python?
...file you've saved is utf-8. The default for Python 2 is ASCII (for Python 3 it's utf-8). This just affects how the interpreter reads the characters in the file.
In general, it's probably not the best idea to embed high unicode characters into your file no matter what the encoding is; you can use ...
File extension for PowerShell 3
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133
PowerShell files for all versions are .ps1 (or .psm1, .psd1, etc.).
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