SCAN.py

def SCAN(sequence,start,direction):
    temp = sequence.copy()
    left = []
    right = []
    x = []
    y = []
    x_approx = []
    y_approx = []
    headmovement = 0
    headmovement_approx = 0
    x.append(start)
    if(direction=="Left"):
        for i in temp:
            if i<start:
                left.append(i)
            else:
                right.append(i)
        left.sort(reverse = True)
        for i in left:
            x.append(i)
        x.append(0)
        right.sort()
        for i in right:
            x.append(i)
        x_approx.append(start)
        x_approx.append(min(x))
        x_approx.append(max(x))
        headmovement_approx = abs(start-0)
        headmovement_approx = headmovement_approx + abs(0-max(x))
    elif(direction=="Right"):
        for i in temp:
            if i>start:
                right.append(i)
            else:
                left.append(i)
        right.sort()
        for i in right:
            x.append(i)
        x.append(CYLINDER_MAX)
        left.sort(reverse = True)
        for i in left:
            x.append(i)
        x_approx.append(start)
        x_approx.append(max(x))
        x_approx.append(min(x))
        headmovement_approx = abs(start-199)
        headmovement_approx = headmovement_approx + abs(199-min(x))
    
    
    
    y_approx.append(0)
    size = len(x)
    for i in range(0,size):
        y.append(-i)
        if(x[i]==0 or x[i]==199):
            y_approx.append(-i)
        if i!=(size-1):
            headmovement = headmovement + abs(x[i]-x[i+1])
        else:
            y_approx.append(-i)
    string = 'Headmovement = ' + str(headmovement) + ' cylinders'
    string2 = str(x)
    string3 = 'Approx Headmovement = ' + str(headmovement_approx) + ' cylinders'
    
    plt.plot(x,y, color="green", markerfacecolor = 'blue', marker='o', markersize = 5, linewidth = 2, label="SCAN")
    plt.plot(x_approx,y_approx, dashes = [6,2] , color="red", markerfacecolor = 'red', marker='D', markersize = 5, linewidth = 0.5, label="Approx SCAN")
    plt.ylim = (0,size)
    plt.xlim = (0,CYLINDER_MAX)
    plt.yticks([])
    plt.title("SCAN Scheduling Algorithm")
    plt.text(182.5, -10.85, string, horizontalalignment='center',verticalalignment='center',fontsize=12)
    plt.text(182.5, -12.5, string2, horizontalalignment='center',verticalalignment='center',fontsize=12)
    plt.text(182.5, -11.5, string3, horizontalalignment='center',verticalalignment='center',fontsize=12)
    plt.show()