如何获取单个行的值？

Question

I'm making a program that uses a list and has 2 rows and 5 columns. Every element is an entry. I want to be able to access all the columns of an entire row in the list.

When I access all the elements across all rows at once, it works. But when I try to get the values of a single row it doesn't work

This is the code that works:

#Build the grid and append to the listCounter list.
for i in range(2):
    for x in range(5):
        entry = Entry(frame, text="", width=5)
        entry.grid(row=i, column=x)
        listCounter.append(entry)

#Get the value of every row
def btnClick():
    sum = 0
    for puntuation in listCounter:           
        sum += int(puntuation.get())
    print(sum)

But when I try to get all entries of a single row using listCounter[0] , it doesn't work:

def btnClick():
    sum = 0
    for puntuation in listCounter[0]:           
        sum += int(puntuation.get())
    print(sum)

And I get the following error:

Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Users\Rober\AppData\Local\Programs\Python\Python37- 
32\lib\tkinter\__init__.py", line 1705, in __call__
return self.func(*args)
File "D:/PyProjects/TestCanvas/Connect4.py", line 25, in btnClick
for puntuation in listCounter[0]:
File "C:\Users\Rober\AppData\Local\Programs\Python\Python37- 
32\lib\tkinter\__init__.py", line 1489, in cget
return self.tk.call(self._w, 'cget', '-' + key)
TypeError: can only concatenate str (not "int") to str

So I've tried to get info about the listCounter :

print(type(listCounter))   --> <class 'list'>
print(type(listCounter[0]) --> <class 'tkinter.Entry'>

What exactly is the problem here and how do I solve it?

Answer 1

If you want to create a proper 2D list (a list-of-lists), you need to create the nested elements explicitly:

for i in range(2):
    row = []
    for x in range(5):
        entry = Entry(frame, text="", width=5)
        entry.grid(row=i, column=x)
        row.append(entry)
    listCounter.append(row)

Now you will be able to index listCounter[0] and get the elements of the first row. Previously, you had listCounter as a single list of 10 elements, and listCounter[0] was understandably just an Entry object.

Answer 2

So, looking at this, I think your confusion is of the "type" of listCounter. It is not a list of rows, each of which is a list of items (columns). It's a list of each Entry , each of which independently controls the row and column it is in. It's like if you took apart a chessboard's rows and put them all next to each other. You can still go through each row independently, it just takes a little work.

It looks like there's 2 rows and 5 columns, so there's 10 entries total. If you try to print out len(puntuation) , I'd guess it's 10 . It also looks like it's stored in row-major order . So, the sum of the first row would be:

def btnClick():
    sum = 0
    for puntuation in listCounter[0:5]:
        sum += puntuation.get()
    print(sum)

Let me know if that helps!