Python Question - Formatting

Question

I am working on a time lapse project, and I would like to be able to save my files with a time stamp (something like YYYYMMDD-HMS.jpg). So I used the code below: import time
import picamera

VIDEO_DAYS = 1
FRAMES_PER_HOUR = 360
FRAMES = FRAMES_PER_HOUR * 3 * VIDEO_DAYS

file = time.strftime("%Y%m%d-%H%M%S")

def capture_frame(frame):
 with picamera.PiCamera() as cam:
 time.sleep(2)
 cam.led = False #Turn off the Red LED
 cam.capture('/home/pi/camera/'+file+'.jpg' % (frame))

# Capture the images
for frame in range(FRAMES):
 # Note the time before the capture
 start = time.time()
 capture_frame(frame)
 # Wait for the next capture. Note that we take into
 # account the length of time it took to capture the
 # image when calculating the delay
 time.sleep(
 int(60 * 60 / FRAMES_PER_HOUR) - (time.time() - start)
 ) I end up getting this error message. File "camera.py", line 20, in <module>
 capture_frame(frame)
 File "camera.py", line 14, in capture_frame
 cam.capture('/home/pi/camera/'+file+'.jpg' % (frame))
TypeError: not all arguments converted during string formatting I feel like I am missing something simple or obvious, but I am not sure what that is, and my inexperience is starting to show. Any help would be greatly appreciated, thank you!

balearicdynamics · Accepted Answer

You shown me just what I was trying to explain !

cam.capture('/home/pi/Desktop/frame%03d.jpg' % frame)

you see that the % frame is a variable that can't fit space (in your code) in the compound string. In the origina the /frame%03d.jpg Means:

Format three integer digits left-aligned with zeroes in this point, then at the end of the string you have the variable that is used creating the file name.

I suggest that you create before a string '/home/pi/camera/' + file + '%03d.jpg' so you don't stress the program to recreate for a lot of times always the same string that is the formatter

Then place the string in your command with the %frame that is the replacement variable for the formatter.

mikedavis · Answer

I think that it is not chained to the string. I believe that it basically counts the number of pictures that are taken in that portion of the code. The original code I used (and always works) is from the RaspberryPi.org site.

import time import picamera VIDEO_DAYS = 5 FRAMES_PER_HOUR = 1 FRAMES = FRAMES_PER_HOUR * 24 * VIDEO_DAYS def capture_frame(frame): with picamera.PiCamera() as cam: time.sleep(2) cam.capture('/home/pi/Desktop/frame%03d.jpg' % frame) # Capture the images for frame in range(FRAMES): # Note the time before the capture start = time.time() capture_frame(frame) # Wait for the next capture. Note that we take into # account the length of time it took to capture the # image when calculating the delay time.sleep( int(60 * 60 / FRAMES_PER_HOUR) - (time.time() - start) )

Python Question - Formatting

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