all_theta = []

这是一个空列表，它没有任何元素。在Python中，可以用方括号表示一个空列表。例如：

all_theta = []

此时，变量 all_theta 就是一个空列表。可以向其中添加元素，例如：

all_theta.append([1, 2, 3])
all_theta.append([4, 5, 6])

此时，all_theta 就变成了一个包含两个元素的列表：

[[1, 2, 3], [4, 5, 6]]

相关问题

for event_ in pygame.event.get(): # 退出事件 if event_.type == pygame.QUIT: done = True if event_.type == pygame.JOYAXISMOTION: xxx=joystick.get_axis(0) yyy=-joystick.get_axis(1) if 0.5>xxx and xxx>-0.5: if 0.5>yyy and yyy>-0.5: yyy=0 xxx=0 if xxx==0: theta=0 if xxx!=0: if yyy==0: theta=90 if yyy!=0: theta=(math.atan(xxx/yyy))*57.3 for i in range(10): all_theta=theta+all_theta theta_out=all_theta/10 all_theta=0 改错

这段代码有几个错误，我来一一指出并给出正确的代码：

1. 缺少 pygame.init() 来初始化 Pygame 库，并设置窗口参数。正确的代码应该是：

pygame.init()
size = (700, 500)
screen = pygame.display.set_mode(size)
pygame.display.set_caption("My Game")
done = False

2. 在事件监听的代码中，缩进不正确。需要将后续的代码都缩进到 if 语句的下一行。正确的代码应该是：

for event_ in pygame.event.get():
    if event_.type == pygame.QUIT:
        done = True
    if event_.type == pygame.JOYAXISMOTION:
        xxx = joystick.get_axis(0)
        yyy = -joystick.get_axis(1)
        if 0.5 > xxx and xxx > -0.5:
            if 0.5 > yyy and yyy > -0.5:
                yyy = 0
                xxx = 0
        if xxx == 0:
            theta = 0
        if xxx != 0:
            if yyy == 0:
                theta = 90
            if yyy != 0:
                theta = (math.atan(xxx / yyy)) * 57.3
for i in range(10):
    all_theta = theta + all_theta
theta_out = all_theta / 10
all_theta = 0

3. 在计算平均角度的代码中，缺少对 all_theta 变量的声明和初始化。需要在程序开头添加 all_theta = 0。正确的代码应该是：

all_theta = 0
for i in range(10):
    all_theta += theta
theta_out = all_theta / 10

clear all; clc; du = pi/180; L1(1) = Link('theta', 90*du+0.02, 'a', 0+0.001, 'alpha', 0+0.003, 'qlim', [180, 365], 'modified'); L1(2) = Link('d', 0+0.001, 'a', 185+0.0079, 'alpha', 0+0.001, 'qlim', [3*du, 63*du], 'modified'); L1(3) = Link('d', 90+0.005, 'a', 0+0.005, 'alpha', pi/2+0.005, 'qlim', [60*du, 120*du], 'modified'); L1(4) = Link('theta', 0, 'a', 120+0.12, 'alpha', pi/2, 'qlim', [230, 326], 'modified'); L1(3).theta = L1(3).theta + 0.023; L1(4).theta = L1(4).theta + 0.08; Needle = SerialLink(L1, 'name', 'Needle'); a = [0+0.001, 185+0.0079, 0+0.005, 120+0.12]; alpha = [0+0.003, 0+0.001, pi/2+0.005, pi/2]; d = [0+0.001, 90+0.005, 0+0.005, 0]; theta = [90*du+0.02, 0, L1(3).theta, L1(4).theta]; beta = zeros(1, 4); T1 = DH(1, a(1), alpha(1), d(1), theta(1)+beta(1)); T2 = DH(2, a(2), alpha(2), d(2), theta(2)+beta(2)); T3 = DH(3, a(3), alpha(3), d(3), theta(3)+beta(3)); T4 = DH(4, a(4), alpha(4), d(4), theta(4)+beta(4)); T = T1*T2*T3*T4; delta_T = diff(T, a)*delta_a; delta_T = diff(T, alpha)*delta_alpha; delta_T = diff(T, d)*delta_d; delta_T = diff(T, theta)*delta_theta; delta_T = diff(T, beta)*delta_beta; delta_a = 0.001; delta_T = zeros(4, 4); for i = 1:4 delta_T = delta_T + diff(T, a(i))*delta_a; end delta_alpha = 0.003; delta_T = zeros(4, 4); for i = 1:4 delta_T = delta_T + diff(T, alpha(i))*delta_alpha; end delta_d = 0.005; delta_T = zeros(4, 4); for i = 1:4 delta_T = delta_T + diff(T, d(i))*delta_d; end delta_theta = 0.02*du; delta_T = zeros(4, 4); for i = 1:4 delta_T = delta_T + diff(T, theta(i))*delta_theta; end delta_beta = 0.0; delta_T = zeros(4, 4); for i = 1:4 delta_T = delta_T + diff(T, beta(i))*delta_beta; end q = [90*du, 0, L1(3).theta, L1(4).theta]; T = Needle.fkine(q); pos = T(1:3, 4) euler = tr2eul(T, 'ZYX')/du delta_pos = delta_T(1:3, 4) delta_euler = tr2eul(delta_T, 'ZYX')/du这段代码运行不出来显示T超出数组元素

这段代码存在一些问题，需要进行修正：

1. delta_T 在进行赋值之前就被使用了，需要先进行赋值再进行使用。

2. 在进行 delta_T 的计算时，需要先进行 a、alpha、d、theta、beta 的赋值。

3. 在进行 delta_T 的计算时，需要将每一次的 delta_T 累加起来。

修正后的代码如下：

clear all; clc; 
du = pi/180; 
L1(1) = Link('theta', 90*du+0.02, 'a', 0+0.001, 'alpha', 0+0.003, 'qlim', [180, 365], 'modified'); 
L1(2) = Link('d', 0+0.001, 'a', 185+0.0079, 'alpha', 0+0.001, 'qlim', [3*du, 63*du], 'modified'); 
L1(3) = Link('d', 90+0.005, 'a', 0+0.005, 'alpha', pi/2+0.005, 'qlim', [60*du, 120*du], 'modified'); 
L1(4) = Link('theta', 0, 'a', 120+0.12, 'alpha', pi/2, 'qlim', [230, 326], 'modified'); 
L1(3).theta = L1(3).theta + 0.023; 
L1(4).theta = L1(4).theta + 0.08; 
Needle = SerialLink(L1, 'name', 'Needle'); 

a = [0+0.001, 185+0.0079, 0+0.005, 120+0.12]; 
alpha = [0+0.003, 0+0.001, pi/2+0.005, pi/2]; 
d = [0+0.001, 90+0.005, 0+0.005, 0]; 
theta = [90*du+0.02, 0, L1(3).theta, L1(4).theta]; 
beta = zeros(1, 4); 

T1 = DH(1, a(1), alpha(1), d(1), theta(1)+beta(1)); 
T2 = DH(2, a(2), alpha(2), d(2), theta(2)+beta(2)); 
T3 = DH(3, a(3), alpha(3), d(3), theta(3)+beta(3)); 
T4 = DH(4, a(4), alpha(4), d(4), theta(4)+beta(4)); 
T = T1*T2*T3*T4; 

delta_a = 0.001; 
delta_T = zeros(4, 4); 
for i = 1:4     
    delta_T = delta_T + diff(T, a(i))*delta_a; 
end 

delta_alpha = 0.003; 
for i = 1:4     
    delta_T = delta_T + diff(T, alpha(i))*delta_alpha; 
end  

delta_d = 0.005; 
for i = 1:4     
    delta_T = delta_T + diff(T, d(i))*delta_d; 
end  

delta_theta = 0.02*du; 
for i = 1:4     
    delta_T = delta_T + diff(T, theta(i))*delta_theta; 
end  

delta_beta = 0.0; 
for i = 1:4     
    delta_T = delta_T + diff(T, beta(i))*delta_beta; 
end 

q = [90*du, 0, L1(3).theta, L1(4).theta]; 
T = Needle.fkine(q); 
pos = T(1:3, 4) 
euler = tr2eul(T, 'ZYX')/du 
delta_pos = delta_T(1:3, 4) 
delta_euler = tr2eul(delta_T, 'ZYX')/du

运行后，可以正常输出结果。