如何确定绘制线图的一系列数字的正确域？ [英] how to determine a correct domain for a range of numbers for drawing a line-graph?
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问题描述
我想创建一个线图，但是数字的范围有时与它不一样：
<1,2,5,8,10
有时候也是这样：
-5，-1,4,5,15，8,20，...
通过学习excel和openoffice，我明白它们可以表示一个范围类似于：
minNumber - k to maxNumber + k
，它们将Y轴分成相等的区域。
是否有任何特定的公式当我看到这个问题时，我发现商业产品在扩展范围方面做得不错，可以达到足够的效果令人愉快的圆形数字为他们的刻度。如果这是您感兴趣的内容，请查看我编写的这个C＃代码以尝试不同的算法：
使用系统;
使用System.Collections.Generic;
使用System.Linq;
使用System.Text;
名称空间TickPicker
{
类TickPicker
{
double tickLow;
double tickHigh;
double tickUnit;
double tickCount;
// static double [] targetUnits = {1，2，5，10};
static double [] targetUnits = {1，2，2.5，5，10};
static int [] roundFactors = {1，5，4，2，1};
// static double [] targetUnits = {1,1.5，2.5，5，10};
// static double [] targetUnits = {1，1.25，2，2.5，5，10};
// static double [] targetUnits = {1，1.25，1.5，2，2.5，5，10};
// static double [] targetUnits = {1，1.25，2,5，10};
// static double [] targetUnits = {1，1.25，1.5，2,5，10};
static double [] targetLogs = arrayLog（targetUnits）;
TickPicker（双低，双高，int tickCountGoal）
{
双倍范围=高 - 低;
double divGoal = range /（tickCountGoal - 2）;
double logGoal = Math.Log10（divGoal）;
double powerFactor = Math.Floor（logGoal）;
logGoal = logGoal - powerFactor;
int closestIndex = findClosest（targetLogs，logGoal）;
tickUnit = targetUnits [closestIndex] *（Math.Pow（10，powerFactor））;
//确保实际范围包含目标范围
// roundFactor不鼓励在低和高范围中的.5
int roundFactor = roundFactors [closestIndex];
tickLow = Math.Floor（低/ tickUnit / roundFactor）* tickUnit * roundFactor;
tickHigh = Math.Ceiling（high / tickUnit / roundFactor）* tickUnit * roundFactor;
tickCount =（tickHigh - tickLow）/ tickUnit;
}
static double [] arrayLog（double [] inputs）
{
double [] retVal = new double [inputs.Length];
int x = 0;
foreach（输入中的双输入）
{
retVal [x] = Math.Log10（inputs [x]）;
x ++;
}
return retVal;
static int findClosest（double [] candidates，double input）
{
int low = 0;
for（int i = 1; i< candidates.Length&&& input> candidates [i]; i ++）
{
low = i;
}
int high = low + 1;
返回候选人[高] - 输入<输入 - 候选人[低]？前高后低;
}
静态无效testPicker（双低，双高，nt tickCountGoal）
{
TickPicker picker = new TickPicker（low，high，tickCountGoal）;
System.Console.WriteLine（[{0}：{1}] / {2}给出{5}个{6}个单位的{[3}：{4}]，低，高，tickCountGoal，picker.tickLow，picker.tickHigh，picker.tickCount，picker.tickUnit）;
}
static void Main（string [] args）
{
testPicker（4.7，39.2，13）;
testPicker（4.7，39.2，16）;
testPicker（4.7，39.2，19）;
testPicker（4.7，39.2，21）;
testPicker（4.7，39.2，24）;
testPicker（1967,2011,20）;
testPicker（1967，2011，10）;
testPicker（2.71，3.14，5）;
testPicker（.0568，13，20）;
}
}
}
I want to create a line graph but the range of numbers are different sometimes its like :
1,2,5,8,10
and sometimes its like :
-5 , -1 , 4 , 5, 15 , 8 ,20 ,...
by studying excel and openoffice I understand that they can indicate a range something like :
minNumber - k to maxNumber + k
and they divide the Y axis into equal area.
is there any specific formula for doing these things ?
解决方案
When I looked at this problem I found that commercial products do a nice job of extending the range just enough to achieve pleasingly nice round numbers for their tick marks. If this is something you are interested in, take a look at this C# code that I wrote to try out different algorithms:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace TickPicker
{
class TickPicker
{
double tickLow;
double tickHigh;
double tickUnit;
double tickCount;
//static double[] targetUnits = { 1, 2, 5, 10 };
static double[] targetUnits = { 1, 2, 2.5, 5, 10 };
static int[] roundFactors = { 1, 5, 4, 2, 1 };
//static double[] targetUnits = { 1, 1.5, 2.5, 5, 10 };
//static double[] targetUnits = { 1, 1.25, 2, 2.5, 5, 10 };
//static double[] targetUnits = { 1, 1.25, 1.5, 2, 2.5, 5, 10 };
//static double[] targetUnits = { 1, 1.25, 2, 5, 10 };
//static double[] targetUnits = { 1, 1.25, 1.5, 2, 5, 10 };
static double[] targetLogs = arrayLog(targetUnits);
TickPicker(double low, double high, int tickCountGoal)
{
double range = high - low;
double divGoal = range / (tickCountGoal - 2);
double logGoal = Math.Log10(divGoal);
double powerFactor = Math.Floor(logGoal);
logGoal = logGoal - powerFactor;
int closestIndex = findClosest(targetLogs, logGoal);
tickUnit = targetUnits[closestIndex] * (Math.Pow(10, powerFactor));
// Ensure the actual range encompasses the intended range
// The roundFactor discourages the .5 on the low and high range
int roundFactor = roundFactors[closestIndex];
tickLow = Math.Floor(low / tickUnit / roundFactor) * tickUnit * roundFactor;
tickHigh = Math.Ceiling(high / tickUnit / roundFactor) * tickUnit * roundFactor;
tickCount = (tickHigh - tickLow) / tickUnit;
}
static double[] arrayLog(double[] inputs)
{
double[] retVal = new double[inputs.Length];
int x = 0;
foreach (double input in inputs)
{
retVal[x] = Math.Log10(inputs[x]);
x++;
}
return retVal;
}
static int findClosest(double[] candidates, double input)
{
int low = 0;
for(int i = 1; i < candidates.Length && input > candidates[i]; i++)
{
low = i;
}
int high = low + 1;
return candidates[high] - input < input - candidates[low] ? high : low;
}
static void testPicker(double low, double high, int tickCountGoal)
{
TickPicker picker = new TickPicker(low, high, tickCountGoal);
System.Console.WriteLine("[{0}:{1}]/{2} gives [{3}:{4}] with {5} ticks of {6} units each.", low, high, tickCountGoal, picker.tickLow, picker.tickHigh, picker.tickCount, picker.tickUnit);
}
static void Main(string[] args)
{
testPicker(4.7, 39.2, 13);
testPicker(4.7, 39.2, 16);
testPicker(4.7, 39.2, 19);
testPicker(4.7, 39.2, 21);
testPicker(4.7, 39.2, 24);
testPicker(1967, 2011, 20);
testPicker(1967, 2011, 10);
testPicker(2.71, 3.14, 5);
testPicker(.0568, 13, 20);
}
}
}
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