Rotating x axis labels in R for barplot
use optional parameter las=2 . barplot(mytable,main=”Car makes”,ylab=”Freqency”,xlab=”make”,las=2)
graph
Difference between Prim’s and Dijkstra’s algorithms?
Prim’s algorithm constructs a minimum spanning tree for the graph, which is a tree that connects all nodes in the graph and has the least total cost among all trees that connect all the nodes. However, the length of a path between any two nodes in the MST might not be the shortest path between … Read more
Python equivalent of D3.js
You could use d3py a python module that generate xml pages embedding d3.js script. For example : import d3py import networkx as nx import logging logging.basicConfig(level=logging.DEBUG) G = nx.Graph() G.add_edge(1,2) G.add_edge(1,3) G.add_edge(3,2) G.add_edge(3,4) G.add_edge(4,2) # use ‘with’ if you are writing a script and want to serve this up forever with d3py.NetworkXFigure(G, width=500, height=500) as … Read more
How do you represent a graph in Haskell?
In shang’s answer you can see how to represent a graph using laziness. The problem with these representations is that they are very difficult to change. The knot-tying trick is useful only if you’re going to build a graph once, and afterward it never changes. In practice, should I actually want to do something with … Read more
How to trace the path in a Breadth-First Search?
You should have look at http://en.wikipedia.org/wiki/Breadth-first_search first. Below is a quick implementation, in which I used a list of list to represent the queue of paths. # graph is in adjacent list representation graph = { ‘1’: [‘2’, ‘3’, ‘4’], ‘2’: [‘5’, ‘6’], ‘5’: [‘9′, ’10’], ‘4’: [‘7’, ‘8’], ‘7’: [’11’, ’12’] } def bfs(graph, … Read more
how to draw directed graphs using networkx in python?
Fully fleshed out example with arrows for only the red edges: import networkx as nx import matplotlib.pyplot as plt G = nx.DiGraph() G.add_edges_from( [(‘A’, ‘B’), (‘A’, ‘C’), (‘D’, ‘B’), (‘E’, ‘C’), (‘E’, ‘F’), (‘B’, ‘H’), (‘B’, ‘G’), (‘B’, ‘F’), (‘C’, ‘G’)]) val_map = {‘A’: 1.0, ‘D’: 0.5714285714285714, ‘H’: 0.0} values = [val_map.get(node, 0.25) for node … Read more
How does Dijkstra’s Algorithm and A-Star compare?
Dijkstra is a special case for A* (when the heuristics is zero).
Why use Dijkstra’s Algorithm if Breadth First Search (BFS) can do the same thing faster?
Dijkstra allows assigning distances other than 1 for each step. For example, in routing the distances (or weights) could be assigned by speed, cost, preference, etc. The algorithm then gives you the shortest path from your source to every node in the traversed graph. Meanwhile BFS basically just expands the search by one “step” (link, … Read more
How to plot multiple functions on the same figure, in Matplotlib?
To plot multiple graphs on the same figure you will have to do: from numpy import * import math import matplotlib.pyplot as plt t = linspace(0, 2*math.pi, 400) a = sin(t) b = cos(t) c = a + b plt.plot(t, a, ‘r’) # plotting t, a separately plt.plot(t, b, ‘b’) # plotting t, b separately … Read more
Dependency graph of Visual Studio projects
I needed something similar, but didn’t want to pay for (or install) a tool to do it. I created a quick PowerShell script that goes through the project references and spits them out in a yuml.me friendly-format instead: Function Get-ProjectReferences ($rootFolder) { $projectFiles = Get-ChildItem $rootFolder -Filter *.csproj -Recurse $ns = @{ defaultNamespace = “http://schemas.microsoft.com/developer/msbuild/2003” … Read more