'NoneType'對象不可迭代

Question

我在運行代碼時遇到了這個錯誤，我不明白爲什麼。我試圖打印變量'j'，但它確實有一個非空值。

這裏的回溯：

[array([ 0., 10.]), array([ 0. , 0.59]), array([ 0. , 1.35]), array([ 0., 1.])] 
Traceback (most recent call last): 
    File "model.py", line 300, in <module> 
    main() 
    File "model.py", line 293, in main 
    training(model, data) 
    File "model.py", line 272, in training 
    [lambdas, clus, conn] = model.learn(j,env) 
TypeError: 'NoneType' object is not iterable 

從功能訓練（模型，數據）：

for j in trainingblock: 
     print j 
     [res,prob,outunits,outacts,act,dist] = model.stimulate(j, env) 
     if res == True: 
      nitemscorrect += 1 
      accuracy = 1 
      [lambdas, clus, conn] = model.learn(j,env) 
     else: 
      accuracy = 0 

Answer 1

出現的錯誤在這裏：

[lambdas, clus, conn] = model.learn(j,env) 

Python是試圖解開值由learn返回到三個左側變量中。但是，該函數已返回None，因此python無法將值分配給這些變量並引發異常。

x, y, z = [1, 2, 3] # works 
x, y, z = None # error