From d624d8483e15efa59c9165d6f883caf65175bd4e Mon Sep 17 00:00:00 2001
From: tomsmeding <tom.smeding@gmail.com>
Date: Thu, 6 Oct 2016 12:16:37 +0200
Subject: Initial

---
 histogram.cpp | 129 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 histogram.cpp

(limited to 'histogram.cpp')

diff --git a/histogram.cpp b/histogram.cpp
new file mode 100644
index 0000000..ab6d651
--- /dev/null
+++ b/histogram.cpp
@@ -0,0 +1,129 @@
+#include <iostream>
+#include <iomanip>
+#include <vector>
+#include <cmath>
+#include <cassert>
+
+using namespace std;
+
+const char *argv0;
+
+void usage(){
+	cerr<<"Usage: "<<argv0<<" [<lowbound> <highbound>] [<nbins>]"<<endl
+	    <<"Prints a simple histogram of stdin data in your terminal, using"<<endl
+	    <<"either the given lower and upper bounds, or the minimum and"<<endl
+	    <<"maximum extracted from the data."<<endl
+	    <<"The number of bins can also be passed."<<endl
+	    <<"Data on stdin is assumed to be a list of floating-point values."<<endl;
+}
+
+double parsefloat(const char *s,const char *errprefix){
+	char *endp;
+	double v=strtod(s,&endp);
+	if(!s[0]||*endp){
+		cerr<<errprefix<<" '"<<s<<"'"<<endl;
+		usage();
+		exit(1);
+	}
+	return v;
+}
+
+int parseint(const char *s,const char *errprefix){
+	char *endp;
+	int v=strtol(s,&endp,10);
+	if(!s[0]||*endp){
+		cerr<<errprefix<<" '"<<s<<"'"<<endl;
+		usage();
+		exit(1);
+	}
+	return v;
+}
+
+int main(int argc,char **argv){
+	argv0=argv[0];
+
+	const int BARWIDTH=80;
+
+	double low,high;
+	bool havebounds;
+	int nbins=10;
+
+	if(argc==1){
+		havebounds=false;
+	} else if(argc==2){
+		havebounds=false;
+		nbins=parseint(argv[1],"Invalid number");
+	} else if(argc==3){
+		havebounds=true;
+		low=parsefloat(argv[1],"Invalid number");
+		high=parsefloat(argv[2],"Invalid number");
+	} else if(argc==4){
+		havebounds=true;
+		low=parsefloat(argv[1],"Invalid number");
+		high=parsefloat(argv[2],"Invalid number");
+		nbins=parseint(argv[3],"Invalid number");
+	} else {
+		usage();
+		return 1;
+	}
+
+	if(nbins<1){
+		cerr<<"Invalid number of bins '"<<nbins<<"'"<<endl;
+		usage();
+		return 1;
+	}
+
+	double minval=INFINITY,maxval=-INFINITY;
+	vector<double> values;
+	while(true){
+		double v;
+		cin>>v;
+		if(!cin)break;
+		values.push_back(v);
+		if(v<minval)minval=v;
+		if(v>maxval)maxval=v;
+	}
+	if(!havebounds){
+		low=minval;
+		high=maxval;
+	}
+
+	sort(values.begin(),values.end());
+
+	vector<int> histogram(nbins);
+
+	int binidx=0,tally=0,maxtally=-1;
+	for(double v : values){
+		if(v<low||v>high){
+			cerr<<"Point "<<v<<" out of range!"<<endl;
+			continue;
+		}
+		int bin=(v-low)/(high-low)*nbins;
+		if(bin==nbins)bin--;
+		assert(bin>=0&&bin<nbins);
+		if(bin!=binidx){
+			histogram[binidx]=tally;
+			if(tally>maxtally)maxtally=tally;
+			binidx=bin;
+			tally=0;
+		}
+		tally++;
+	}
+	histogram[binidx]=tally;
+	if(tally>maxtally)maxtally=tally;
+
+	char fullbar[BARWIDTH+1];
+	memset(fullbar,'#',BARWIDTH);
+	fullbar[BARWIDTH]='\0';
+	char emptybar[BARWIDTH+1];
+	memset(emptybar,' ',BARWIDTH);
+	emptybar[BARWIDTH]='\0';
+
+	for(int i=0;i<(int)histogram.size();i++){
+		int tally=histogram[i];
+		int width=BARWIDTH*tally/maxtally;
+		cout<<fullbar+BARWIDTH-width<<emptybar+width
+		    <<" ("<<setw(11)<<low+(double)i/nbins*(high-low)<<" - "<<setw(11)<<low+(double)(i+1)/nbins*(high-low)<<")"
+		    <<" ["<<tally<<"]"<<endl;
+	}
+}
-- 
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