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Creating dataframe from a dictionary where entries have different lengths
....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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Differences in boolean operators: & vs && and | vs ||
I know the rules for && and || but what are & and | ? Please explain these to me with an example.
11 Ans...
What is the printf format specifier for bool?
Since ANSI C99 there is _Bool or bool via stdbool.h . But is there also a printf format specifier for bool?
8 Answer...
numpy matrix vector multiplication [duplicate]
...ollowing normal matrix multiplication rules, a (n x 1) vector is expected, but I simply cannot find any information about how this is done in Python's Numpy module.
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How do I check if there are duplicates in a flat list?
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Use set() to remove duplicates if all values are hashable:
>>> your_list = ['one', 'two', 'one']
>>> len(your_list) != len(set(your_list))
True
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impro...
Behaviour of increment and decrement operators in Python
I notice that a pre-increment/decrement operator can be applied on a variable (like ++count ). It compiles, but it does not actually change the value of the variable!
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Determine font color based on background color
Given a system (a website for instance) that lets a user customize the background color for some section but not the font color (to keep number of options to a minimum), is there a way to programmatically determine if a "light" or "dark" font color is necessary?
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Virtual member call in a constructor
I'm getting a warning from ReSharper about a call to a virtual member from my objects constructor.
18 Answers
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String.IsNullOrWhiteSpace in LINQ Expression
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You need to replace
!string.IsNullOrWhiteSpace(b.Diameter)
with
!(b.Diameter == null || b.Diameter.Trim() == string.Empty)
For Linq to Entities this gets translated into:
DECLARE @p0 VarChar(1000) = ''
...
WHERE NOT (([t0].[Diameter] IS NULL) OR (LTRIM(RTRIM([t0].[D...
What is PECS (Producer Extends Consumer Super)?
...ly stuffing items in, it is a consumer and you should use super. If you do both with the same collection, you shouldn't use either extends or super.
Suppose you have a method that takes as its parameter a collection of things, but you want it to be more flexible than just accepting a Collection&l...