如何循环使用 None 类型的嵌套数组

Question

I'm trying to go through each row of my field and then each column within the row, but my field is made of None for the empty spaces that I need. My code gives a type error NoneType object is unsubscriptable, so how can I go about skipping the Nones in my field?

field = [ [['PEASH', 5], None, None, None, None, None, ['ZOMB', 15]],
          [['PEASH', 5], None, None, None, None, None, ['ZOMB', 15]],
          [None, None, None, None, None, None, None],
          [None, None, None, None, None, None, None],
          [None, None, None, None, None, None, None] ]

num_rows=len(field)
num_columns=len(field[0])

lane = 0
row_counter = -1
column_counter = -1
for row in range(num_rows):
    row_counter += 1
    print('rowcounter is at',row_counter)
    print(row)
    for column in range(num_columns): #for each column, 
        column_counter += 1

        element = field[row][column] 
        print(element) #now element will be ['peash',15]
        if element[0] == 'PEASH':
            print('yes there is a peashooter in',row_counter,column_counter)
            

Answer 1

simply change

if element[0] == 'PEASH':
    print('yes there is a peashooter in',row_counter,column_counter)

to

if element is not None:
    if element[0] == 'PEASH':
        print('yes there is a peashooter in',row_counter,column_counter)

Answer 2

This should do it:

if element and element[0] == 'PEASH'

Answer 3

Explanations are in the comments.

field = [ [['PEASH', 5], None, None, None, None, None, ['ZOMB', 15]],
          [['PEASH', 5], None, None, None, None, None, ['ZOMB', 15]],
          [None, None, None, None, None, None, None],
          [None, None, None, None, None, None, None],
          [None, None, None, None, None, None, None] ]

# Python, as a high-level language, can perform iteration in the follow way
for i, row in enumerate(field): # E.g. first row => i = 0; row = [['PEASH', 5], None, None, None, None, None, ['ZOMB', 15]]
    for j, element in enumerate(row):
        print(element) # I don't know what's the use of this, but just to keep it as-is in your code
        if element is None:
            continue # Skip ahead to next element
        if element[0] == 'PEASH':
            print('yes there is a peashooter in',i,j)

Answer 4

Try checking if element is equal to "None":

if element[0] == "PEASH" and element is not None:
    print('yes there is a peashooter in',row_counter,column_counter)