使用嵌套的for循环在python中打印简单矩阵

Question

I am having trouble with my assignment.

Print out a 3x3 matrix of “-”s using for loops.

It should look like this:

- - -
- - -
- - -

This is the closest I have come but it's not working

x = "-"
for i in range(3):
    for n in range(3):
        for x in range(3):
            print x,

You will need nested for loops to accomplish this.

I have been trying this for an hour with no luck, can someone please point me in the right direction?

Answer 1

for i in range(21/7):
   print ' '.join(['-' for _ in range(264/88)])

Answer 2

In your code, x is defined to be - , so you shouldn't enumerate over it. I edited your code to produce a working version.

Note that in the internal loop you need to put spaces between the - , while in the external loop you want to move to the next line.

Here is the code for python 3:

x = "-" 
for i in range(3): 
    for n in range(3): 
        print(x, end=' ')
    print('\n')

Here is the code for python 2:

x = "-" 
for i in range(3): 
    for n in range(3): 
        print x,
    print('\n')

Answer 3

Very good start!

Let's think through, what were you trying to achieve with your 3rd loop.
(Hint: you don't need a third loop).

If you talk out what you need to happen it becomes:

1) print a "- " three times. (inner loop)
2) print a new line
3) now go back and repeat steps 1) and 2) three times (outer loop)

That would only be 2 loops, not 3.

Try This:

x = "- "
for i in range(3):
    for n in range(3):
        print x,
    print "\n"

You could even shorten this to

for i in range(3):       # print the following line 3 times
    for n in range(3):   # print 3 dashes, separated by a space
        print "- ",
    print "\n"           # begin a new line

BTW, print x, is proper if using Python 2, but for Python 3, it will need to be changed to print(x, end='') .

Answer 4

construct a matrix using nested loop:

matrix = [[],[],[]]

for x in range(0,3):
  for y in range(0,3):
    matrix[x].append("-")

then print it:

for i in range(3):
  print(matrix[i])