Vertical Bar Graphs in C++ - c++

Question

Ok, I'm trying to make a vertical bar graph from the values in a file. The code below works, to a point that is, and prints horizontally, but one asterisk per line, meaning there are spaces (obviously). Not looking for a spoonfed answer, just a push in the right direction.
using namespace std;
int main()
{
int counter;
cout<<"Please enter a number"<< "\n";
counter=0;
char *fname = "C:/Users/Jordan Moffat/Desktop/coursework/problem2.txt";
int x;
ifstream infile(fname);
while (infile >> x)
{
if (x==0 && x<=10){
cout<<"*"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\n";
}
else if (x>=10 && x<=20){
cout<<"\t"<<"*"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\n";
}
else if (x>=20 && x<=30){
cout<<"\t"<<"\t"<<"*"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\n";
}
else if (x>=30 && x<=40){
cout<<"\t"<<"\t"<<"\t"<<"*"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\n";
}
else if (x>= 40 && x<=50){
cout<<"\t"<<"\t"<<"\t"<<"\t"<<"*"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\n";
}
else if (x>=50 && x<=60){
cout<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"*"<<"\t"<<"\t"<<"\t"<<"\t"<<"\n";
}
else if (x>=60 && x<=70){
cout<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"*"<<"\t"<<"\t"<<"\t"<<"\n";
}
else if (x>=70 && x<=80){
cout<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"*"<<"\t"<<"\t"<<"\n";
}
else if (x>=80 && x<=90){
cout<<"*"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"*"<<"\t"<<"\n";
}
else if (x>=90 && x<=100){
cout<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"\t"<<"*"<<"\n";
}
}
cout<<"====================================================================================="<< "\n";
cout<<"0-9"<<"10-19"<<"20-29"<<"30-39"<<"40-49"<<"50-59"<<"60-69"<<"70-79"<<"80-89"<<"90-100"<<"\n";
system("PAUSE");
}

Answer 1

You have two problems. Apparantly you want to build a histogram and you want to visualize this histogram.
Histogram
One approach to build the histogram requires you to pre-specify the number of bins (homogeneous width), the minimum value (inclusive) and the maximum value (non-inclusive). Then you can compute the index of the bin each item should be assigned to.
Here's an (untested) example:
const int nbins = 10;
const double minval = .0, maxval = 100.;
std::vector<int> bins(nbins, 0);
for (double x; infile >> x; ) {
if (x >= minval && x < maxval) {
// note that integer rounding is probably towards zero, not towards -inf
int idx = floor((x-minval)/(maxval-minval)*nbins);
bins[idx]++;
}
else {
// handle outlier
}
}
Visualization
The approach described in this answer seems appropriate. For large bin counts you may need some normalization procedure, i.e. scaling the values to a range of [0,10] or similar.
Have a look at this (untested) example:
const int chart_height = 10;
const int max_count = *std::max_element(bins.begin(), bins.end());
for (int current_height = chart_height; current_height > 0; --current_height) {
for (int count : bins) {
const int bar_height = (count*chart_height)/max_count;
if (bar_height < current_height)
std::cout << " "; // we're still above the bar
else if (bar_height == current_height)
std::cout << " _ "; // reached the top of the bar
else // bar_height > current_height
std::cout << " | | "; // now the rest of the bar ...
}
std::cout << '\n';
}
With a little bit of fiddling and formatting magic you can also extend it to produce a borderline flexible visualization like this:
11 | _______ _______
| | | | |
| | | | |
| | | | |
| | | | | _______
5 | | | | | | |
| | | | | | |
| | | | | | | _______
| _______ | | | | | | _______ | |
| | | | | | | | | | | | |
+------v----------v----------v----------v----------v----------v-----
3.7 - 4.3 4.3 - 4.9 4.9 - 5.6 5.6 - 6.2 6.2 - 6.8 6.8 - 7.4

Answer 2

To make your bars vertically you need:
get all numbers in an array
determine the range, i.e. compute the max and min value of the array
make a loop over range, printing rows, leaving spaces on columns associate to values lower than the current row is 'depicting'.
here I assume steps 1 & 2 as done, just show the loop and gloss over some detail (note the code doesn't use min and loop from 0)
int values[] = {2,5,1,9,3}, cols = 5, max = 9;
for (int r = 0; r < max; ++r) {
for (int c = 0; c < cols; ++c)
cout << (r + values[c] >= max ? '*' : ' ');
cout << endl;
}
here the output
*
*
*
*
* *
* *
* **
** **
*****

Answer 3

You should read your data into an std::vector
Use two nested loops:
Looping over lines you print where first line is "0->10", second line "10->20" etc.
Looping over the vector, if variable is larger than (linecount-linenumber)*10, print " ", else print "*".
If your data goes from 0 to 100, linecount should be 10.
linenumber is the loop variable from first loop
It is not clear to me how your data is organized in the file. If your data file doesn't contain values which say how many *s each column should have, you should calculate that first.

Answer 4

Just having fun and practicing :)
enter any number sequence you want up to 100 numbers and press 0 to stop and make the graph :)
#include <iostream>
#include <limits>
using namespace std;
int main()
{
const int MAX = 100;
int values[MAX];
int input_number;
int total_number =0;
int largest_number = 0;
for (int i = 0; i < MAX; i++)
{
cin >> input_number;
if (input_number != 0)
{
total_number++;
values[i] = input_number;
}
else if (input_number == 0){
for (int t = 0;t<total_number;t++){
if(values[t]>largest_number)
largest_number = values[t];
}
for (int j = 0; j <largest_number; ++j){
for (int i = 0; i <total_number; ++i)
cout << (j+values[i] >= largest_number ? '*' : ' ') ;
cout << endl;
}
break;
}
}
system ("PAUSE");
return 0; // everything ok
}

Answer 5

I guess only one loop for each if condition you have written is sufficient.
And I agree with Kleist that Looping over variables and print * for each variable

Answer 6

(Similar to the answer of Kleist)
Make an array to define the y-axis (or a formula, based on an index)
Read the numbers from a file a save in a container, so you also know the number of values (x-axis)
double loop, 1 for the y-axis, 1 for the x-axis and find out whether an asterisk must be printed, based on 1.
Let the y-axis counter decrement, so your bars are rising.