爲什麼小網格線不會出現

Question

我很難嘗試讓小網格線出現在圖上。我已經看到了幾個SO問題，this one建議兩個網格對象（一個用於主要，一個用於次要），this one也建議添加minorticks_on。

出於某種原因，次要網格線，當我使用下面的代碼仍然沒有出現，任何人都可以擺脫任何光線請：

from __future__ import division 
from matplotlib import pyplot as plt 
from math import log, sqrt 

x = range(1, 20) 
x_lin = x 
x_log = [log(i) for i in x] 

x2 = [sqrt(i) for i in x] 
x2_exp = x 

ax = plt.subplot(1,1,1) 
p1 = ax.plot(x, x_lin, 'g--', label='linear', linewidth=2) 
p2 = ax.plot(x, x_log, 'b-', label='log', linewidth=3) 
p3 = ax.plot(x2, x2_exp, 'r-', label='exp', linewidth=3) 
l1 = ax.legend() 
g1 = ax.grid(b=True, which='both', color='k', linestyle='-') 
g2 = ax.grid(b=True, which='minor', color='k', linestyle='--') 
ax.minorticks_on 
plt.show() 

這裏是我得到：

Answer 1

更改：ax.minorticks_on至ax.minorticks_on()

Answer 2

繼@ M4rtini給出的答案是校正後的碼和新的圖像：

from __future__ import division 
from matplotlib import pyplot as plt 
from math import log, sqrt 

x = range(1, 20) 
x_lin = x 
x_log = [log(i) for i in x] 

x2 = [sqrt(i) for i in x] 
x2_exp = x 

ax = plt.subplot(1,1,1) 
p1 = ax.plot(x, x_lin, 'g--', label='linear', linewidth=2) 
p2 = ax.plot(x, x_log, 'b-', label='log', linewidth=3) 
p3 = ax.plot(x2, x2_exp, 'r-', label='exp', linewidth=3) 
l1 = ax.legend() 
g1 = ax.grid(b=True, which='major', color='k', linestyle='-', linewidth=0.5) 
g2 = ax.grid(b=True, which='minor', color='k', linestyle='-', linewidth=0.2) 
ax.minorticks_on() 
plt.show()