颜色渐变算法

需求：

给定一组数据，给定渐变颜色两端的颜色值，需要根据这组数据中的每个值大小为其分配一个颜色

算法：

一个需要用颜色表示值大小的数据集weightlist,给定渐变的起始颜色 colorStart={"red":255,"green":50,"blue":47}，结束颜色colorend ={"red":139,"green":20,"blue":10},minNum=min(weightlist),maxNum=max(weightlist),weightlist中的一个值number，计算其对应的颜色值color

$$\frac{number-minNum}{maxNum-minNum}=\frac{color-colorStart}{colorend -colorStart}$$

最终颜色值：

$$color=\frac{(number-minNum)(colorend -colorStart)}{maxNum-minNum}+colorStart$$

将colorR，colorG，colorB分别代入计算

实现

    def getColorstr(value):    #将rgb颜色转换为16进制
        digit = list(map(str, range(10))) + list("ABCDEF")  
        if isinstance(value, tuple): 
            string = '#'      
            for i in value:      
                a1 = i // 16       
                a2 = i % 16      
                string += digit[a1] + digit[a2]     
            return string 
    def gerColorOfWeight1(minNum,maxNum,colorStart,colorend,number): #颜色,根据数值均分
        colorR=(colorend["red"]-colorStart["red"])*(number-minNum)/(maxNum-minNum)+colorStart["red"]
        colorG=(colorend["green"]-colorStart["green"])*(number-minNum)/(maxNum-minNum)+colorStart["green"]
        colorB=(colorend["blue"]-colorStart["blue"])*(number-minNum)/(maxNum-minNum)+colorStart["blue"]
        color= "rgb("+str(int(colorR))+','+str(int(colorG))+','+str(int(colorB))+')'  
        #color=getColorstr((int(colorR),int(colorG),int(colorB)))#转换为16进制颜色
        return color
    colorYouNeed=gerColorOfWeight1(min(weightlist),max(weightlist),{"red":255,"green":50,"blue":47} ,{"red":139,"green":20,"blue":10} ,1000* errornum/linenum)