Statistics and Data Analysis

Step-by-step instructions on how to import & process multiple data files in R (based on the accuracy analysis of 200 cities) Technical details Challenges Visualization of results on the map I have some data collected for each city, each generated as one data file. And I need to run same analysis for all the 200 data files.  I will go through the whole process in one post. It is not too complicated, which I suppose is why most posts I found online only address part of the issue. Summary of the process: 1. Write a program for a single data file that can do all the analysis correctly.  2. Combine functions to get a final function which will produce a single line of output for all the results I need.  3. Use functional ( lappy ) or a loop to iterate over indices of the batch of files, attach every line of results into a data frame or write into an output .csv file.  4. Start with small batches and trach which data file causes an error in the program, modify th

What is the average travel distance in a city calculated from the compactness index?  The compactness of an area (e.g. urban extent) is the ratio between two average distances: d / D . There are two ways to get the numerator d : The average distance of any random point to the center of the circle, d = (128/45pi)*R = 0.9054*R The average distance of any random point to another point in the circle, d = 2/3*R (P.S., this one is easy to calculate, it is the integration of 2 π r/ πR^2  * r = 2r^2/R^2 from 0 to R. The idea is, for any r within range [0, R], the probability that a point on the disc is on that circle is 2 π r/ πR^2, then we integrate r from 0 to R.  See this post .) The circle is called the "Equal-Area circle" which has the equal area as the shape in the study (e.g. urban extent). The denominator D is the average distance of a random point to the center or to another point in the real shape area. The 1st approach (random distance to center) is called pr