How to write data as txt/csv file

OpenMV Products
1

Hi there,
Quick question here on how to save data from the OpenMV camera to a file on the SD card.
I have a piece of code (below) measuring blob area, and I want to save these to the SD card. It works for the blob area (line 29-31) but I also want to save the blob coordinates and elapsed time.
How should I code the write command? Something like this doesn’t seem to work: f.write(“%d\n” % area, blob.cx(), blob.cy(), pyb.elapsed_millis(start)).
Any help much appreciated

Full code here:

import sensor, image, time, pyb, mjpeg, math, uarray

sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QVGA)
sensor.set_windowing([180,160])
sensor.skip_frames(time = 2000)
clock = time.clock()

thresholds = (0, 30)
numbers = [0]
m = mjpeg.Mjpeg('openmv_video.mp4')
img = sensor.snapshot()

clock = time.clock()
start = pyb.millis()
with open("area.txt", "wb") as f:
    while(True):
        clock.tick()
        for blob in img.find_blobs([thresholds], pixels_threshold=20, area_threshold=10, merge=True):
            # These values depend on the blob not being circular - otherwise they will be shaky.
            if blob.elongation() > 0.2:
                img.draw_edges(blob.min_corners(), color=0)
                img.draw_line(blob.major_axis_line(), color=0)
                img.draw_line(blob.minor_axis_line(), color=0)
            # These values are stable all the time.
            img.draw_rectangle(blob.rect(), color=127)
            img.draw_cross(blob.cx(), blob.cy(), color=127)
            area = blob.area()
            print(area, blob.cx(), blob.cy(), pyb.elapsed_millis(start))
        f.write("%d\n" % area)
        m.add_frame(sensor.snapshot())
        if pyb.elapsed_millis(start) > 10000:
            print('over')
            print(time)
            m.close(clock.fps())
            break
2

You’re asking a very basic/general Python question that you can easily find an answer for if you just Google how to format string in Python. But seems you just need to add more place holders: “%d %d %d”%(x, y, z, w) or using format: “{0}, {1}, {2}”.format(x, y, z) etc…

3

Thank you. Indeed a noob question, but I didn’t even know what to google :slight_smile: cheers!