paste_423426.py

import RPi.GPIO as GPIO
import time
GPIO.setmode(GPIO.BOARD)

KEYS = [[1, 2, 3, 4],
        [5, 6, 7, 8],
        [9, 10, 11, 12],
        [13, 14, 15, 16]]
COL = [15, 13, 11, 7]
ROW = [22, 16, 18, 12]

for j in range(4):
    GPIO.setup(COL[j], GPIO.OUT)
    GPIO.output(COL[j], 1)

for i in range(4):
    GPIO.setup(ROW[i], GPIO.IN, pull_up_down=GPIO.PUD_UP)

try:
    while(True):
        time.sleep(0.2)
        for j in range(4):
            GPIO.output(COL[j], 0)

            for i in range(4):
                if GPIO.input(ROW[i]) == 0:
                    print(KEYS[i][j])
                    while(GPIO.input(ROW[i]) == 0):
                        pass
        GPIO.output(COL[j], 1)
except KeyboardInterrupt:
    GPIO.cleanup()