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Split comma-separated strings in a column into separate rows
...odified according to Rich Scriven's comment,
Jaap's two data.table methods and two dplyr / tidyr approaches,
Ananda's splitstackshapesolution,
and two additional variants of Jaap's data.table methods.
Overall 8 different methods were benchmarked on 6 different sizes of data frames using the micro...
How to use if - else structure in a batch file?
I have a question about if - else structure in a batch file. Each command runs individually, but I couldn't use "if - else" blocks safely so these parts of my programme doesn't work. How can I do make these parts run? Thank you.
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How does @synchronized lock/unlock in Objective-C?
Does @synchronized not use "lock" and "unlock" to achieve mutual exclusion? How does it do lock/unlock then?
5 Answers
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How to create and handle composite primary key in JPA
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You can make an Embedded class, which contains your two keys, and then have a reference to that class as EmbeddedId in your Entity.
You would need the @EmbeddedId and @Embeddable annotations.
@Entity
public class YourEntity {
@EmbeddedId
private MyKey myKey;
@Column(name ...
Get exception description and stack trace which caused an exception, all as a string
I've seen a lot of posts about stack trace and exceptions in Python. But haven't found what I need.
11 Answers
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How to use chrome web inspector to view hover code
... hover code for a button? You will have to hover the mouse over the button and thus cannot use it (mouse) in the inspector. Are there any shortcuts or other ways to accomplish this in the inspector?
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Pick a random element from an array
Suppose I have an array and I want to pick one element at random.
16 Answers
16
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Setting different color for each series in scatter plot on matplotlib
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I don't know what you mean by 'manually'. You can choose a colourmap and make a colour array easily enough:
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.cm as cm
x = np.arange(10)
ys = [i+x+(i*x)**2 for i in range(10)]
colors = cm.rainbow(np.linspace(0, 1, len(ys)))
f...
Calculate date from week number
...date of the first day in the week (monday here in Europe). I know the year and the week number? I'm going to do this in C#.
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Why don't self-closing script elements work?
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XHTML 1 specification says:
С.3. Element Minimization and Empty Element Content
Given an empty instance of an element whose content model is not EMPTY (for example, an empty title or paragraph) do not use the minimized form (e.g. use <p> </p> and not <p />)...