Add README

README.md

@@ -0,0 +1,30 @@
+# COVID
+
+Programs to visualize data on covid-19
+
+In includes the following
+
+* extractCases.pl
+
+  Program to download (if necessary) a European CDC database listing
+  the worldwide distribution  of covid-19 cases and deceases, choose
+  some countries and prepare some files for easy plotting of the
+  results.
+
+  To run the program you need a perl compiler/interpreter and the
+  packages Spreadsheet::Read, Spreadsheet::XLSX, Getopt::Long and
+  List::Util. You might also need the program wget and libreoffice.
+
+  Run it without arguments or with the argument --help to get
+  instruccions: `perl extractCases.pl -h`.
+
+  The result is a list of files that can be fed to gnuplot for
+  plotting
+
+* plotcases.g, plotdec.g
+
+  Gnuplot commands that may be loaded by the gnuplot program to plot
+  the number of new cases and new deseased as a function of the total
+  number of cases. `load 'plotcases.g'` and `load 'plotdec.g'`. May
+  need editing according to your choice of countries and the
+  positioning of labels and arrows.