Tutorial by Examples: u

The semantics for this are similar to that of default value substitution, but instead of substituting a default value, it errors out with the provided error message. The forms are ${VARNAME?ERRMSG} and ${VARNAME:?ERRMSG}. The form with : will error our if the variable is unset or empty, whereas the ...

1. URLByDeletingPathExtension: If the receiver represents the root path, this property contains a copy of the original URL. If the URL has multiple path extensions, only the last one is removed. 2. URLByAppendingPathExtension: Returns a new URL made by appending a path extension to the original U...

The figure contains all the plot elements. The main way to create a figure in matplotlib is to use pyplot. import matplotlib.pyplot as plt fig = plt.figure() You can optionally supply a number, which you can use to access a previously-created figure. If a number is not supplied, the last-create...

Project Object Model is the basic unit of Maven and defines the project structure, dependencies, etc. The following are very minimal to create a POM: project root modelVersion – should be set to 4.0.0 groupId – the ID of the project's group artifactId – the ID of the artifact (project) versi...

In [15]: df = pd.DataFrame({"A":[1,1,2,3,1,1],"B":[5,4,3,4,6,7]}) In [21]: df Out[21]: A B 0 1 5 1 1 4 2 2 3 3 3 4 4 1 6 5 1 7 To get unique values in column A and B. In [22]: df["A"].unique() Out[22]: array([1, 2, 3]) In [23]: df[&qu...

An erlang module is a file with couple of functions grouped together. This file usually has .erl extension. A "Hello World" module with name hello.erl is shown below -module(hello). -export([hello_world/0]). hello_world() -> io:format("Hello, World!~n", []). In the...

Creates a image representing a linear gradient of colors. linear-gradient( 0deg, red, yellow 50%, blue); This creates a gradient going from bottom to top, with colors starting at red, then yellow at 50%, and finishing in blue.

An operator can be used to manipulate the flow of objects from Observable to Subscriber. Observable<Integer> integerObservable = Observable.just(1, 2, 3); // creating a simple Integer observable Subscriber<String> mSubscriber = new Subscriber<String>() { @Override publi...

You can use buffers to work with multiple files. When you open a file using :e path/to/file it opens in a new buffer (the command means edit the file). New buffer that holds a temporary copy of the file. You can go to previous buffer with :bp[rev] and next buffer with :bn[ext]. You can go to a...

Commands have one input (STDIN) and two kinds of outputs, standard output (STDOUT) and standard error (STDERR). For example: STDIN root@server~# read Type some text here Standard input is used to provide input to a program. (Here we're using the read builtin to read a line from STDIN.) STDO...

You can use the .Net Math class to do calculations ([System.Math]) If you want to know which methods are available you can use: [System.Math] | Get-Member -Static -MemberType Methods Here are some examples how to use the Math class: PS C:\> [System.Math]::Floor(9.42) 9 PS C:\> [System....

{ echo "contents of home directory" ls ~ } > output.txt

Other examples couldn't clearly explain to me how to trigger the conditional logic. This example also shows that underlying commands will also listen to the -Confirm flag! <# Restart-Win32Computer #> function Restart-Win32Computer { [CmdletBinding(SupportsShouldProcess=$true,Conf...

Ember has a static global method called runInDebug which can run a function meant for debugging. Ember.runInDebug(() => { // this code only runs in dev mode }); In a production build, this method is defined as an empty function (NOP). Uses of this method in Ember itself are stripped from ...

import pandas as pd df = pd.DataFrame({'gender': ["male", "female","female"], 'id': [1, 2, 3] }) >>> df gender id 0 male 1 1 female 2 2 female 3 To encode the male to 0 and female to 1: df.loc[df["gender&quot...

import pandas as pd df = pd.DataFrame(np.random.randn(5, 5), columns=list('ABCDE')) To generate various summary statistics. For numeric values the number of non-NA/null values (count), the mean (mean), the standard deviation std and values known as the five-number summary : min: minimum (smal...

DefaultIfEmpty is used to return a Default Element if the Sequence contains no elements. This Element can be the Default of the Type or a user defined instance of that Type. Example: var chars = new List<string>() { "a", "b", "c", "d" }; chars.Defaul...

import pylab as plt import numpy as np plt.style.use('ggplot') fig = plt.figure(1) ax = plt.gca() # make some testing data x = np.linspace( 0, np.pi, 1000 ) test_f = lambda x: np.sin(x)*3 + np.cos(2*x) # plot the test data ax.plot( x, test_f(x) , lw = 2) # set the axis labels ax...

The cubic-bezier function is a transition timing function which is often used for custom and smooth transitions. transition-timing-function: cubic-bezier(0.1, 0.7, 1.0, 0.1); The function takes four parameters: cubic-bezier(P1_x, P1_y, P2_x, P2_y) These parameters will be mapped to points whic...

The following method computes the sum of integers from 0 to N using recursion. public int sum(final int n) { if (n > 0) { return n + sum(n - 1); } else { return n; } } This method is O(N) and can be reduced to a simple loop using tail-call optimization. In f...