I’ll first give you the code and then explain it a bit: // direction vectors const int dx[] = {+1, 0, -1, 0}; const int dy[] = {0, +1, 0, -1}; // matrix dimensions int row_count; int col_count; // the input matrix int m[MAX][MAX]; // the labels, 0 means unlabeled int label[MAX][MAX]; void dfs(int x, … Read more
First I will remind us how to find the area of a polygon. Once we have done this, the algorithm to find the intersection between a polygon and a circle should be easy to understand. How to find the area of a polygon Let’s look at the case of a triangle, because all the essential … Read more
Convert the path to a polygon of arbitrary precision, and then calculate the area of the polygon. Interactive Demo: Area of Path via Subdivision (broken) At its core the above demo uses functions for adaptively subdividing path into a polygon and computing the area … Read more
I checked on internet for various polygon area formulas(or code) but did not find any one good or easy to implement. Now I have written the code snippet to calculate area of a polygon drawn on earth surface. The polygon can have n vertices with each vertex has having its own latitude longitude. Few Important … Read more
Not possible with CSS. You might check out the Map Hilight jQuery plugin, though. EDIT 10.2011 ImageMapster is a more recent, and more powerful plugin you should also check out.
Find all circle intersections on the outer perimeter (e.g. B,D,F,H on the following diagram). Connect them together with the centres of the corresponding circles to form a polygon. The area of the union of the circles is the area of the polygon + the area of the circle slices defined by consecutive intersection points and … Read more
The numpy and scipy libraries include the composite trapezoidal (numpy.trapz) and Simpson’s (scipy.integrate.simps) rules. Here’s a simple example. In both trapz and simps, the argument dx=5 indicates that the spacing of the data along the x axis is 5 units. import numpy as np from scipy.integrate import simps from numpy import trapz # The y … Read more
Building off of @gnovice’s answer, you can actually create filled plots with shading only in the area between the two curves. Just use fill in conjunction with fliplr. Example: x=0:0.01:2*pi; %#initialize x array y1=sin(x); %#create first curve y2=sin(x)+.5; %#create second curve X=[x,fliplr(x)]; %#create continuous x value array for plotting Y=[y1,fliplr(y2)]; %#create y values for out … Read more
Implementation of Shoelace formula could be done in Numpy. Assuming these vertices: import numpy as np x = np.arange(0,1,0.001) y = np.sqrt(1-x**2) We can redefine the function in numpy to find the area: def PolyArea(x,y): return 0.5*np.abs(np.dot(x,np.roll(y,1))-np.dot(y,np.roll(x,1))) And getting results: print PolyArea(x,y) # 0.26353377782163534 Avoiding for loop makes this function ~50X faster than PolygonArea: %timeit … Read more