the-collector 0.3.0

A library to store robot data in a json file

The Collector

This is still under heavy development

The idea behind this a container that can store data and time tag the data when it is captured. The main structure is a dict which has keys for each data series stored.

Setup

Install

The suggested way to install this is via the pip command as follows:

pip install the_collector

Development

To submit git pulls, clone the repository and set it up as follows:

git clone https://github.com/MomsFriendlyRobotCompany/the-collector
cd the-collector
pip install -r requirements
pip install -e .

Usage

In the code example below, sensor data is saved to a file. Specifically, it is saving:

• imu: accel, gyro, magnetometer

• camera: raspberry pi images.

Every time data is pushed into the Bag file, each data point is given a time stamp. Thus, for the camera, the Bag (which is a dictionary) would have an array of:

bag['camera'] = [[frame0, stamp], [frame1, stamp], ... ]
bag['imu'] = [[imu0, stamp], [imu1, stamp], ... ]

where stamp is a time stamp, frame is an image from from a camera, and imu is an array of [accel, gyro, magnetometer] data. Now to save data to disk:

from the_collector.bagit import BagWriter
import time

# this file name gives a time/date when it was created
# you don't have to do this, 'data.json' would work fine too
filename = 'robot-{}.json'.format(time.ctime().replace(' ', '-'))

# create the writer
bag = BagWriter()
bag.open(filename, ['imu', 'camera'])

# camera images are binary arrays, we are going to base64 encode them
# so we can store them in a json file nicely
bag.stringify('camera')  # this can be a string or an array of keys

try:
        while True:
                # read and get imu data, say: data = imu.read()
                # always push (key, data), push will add a timestamp
                bag.push('imu', data)

                # read camera, say: ret, frame = camera.read()
                bag.push('camera', frame)

except KeyboardError:
        bag.write()  # actually writes the data to disk

To read data from a bag file:

from the_collector.bagit import BagReader

reader = BagReader()
data = reader.load('my_file.json')  # read in the file and conver to dict

# now print everything out
for key, value in data.items():
        print('-- {} -----------------'.format(key))
        for sample in value:
                point, timestamp = sample
                print(timestamp, point)
        print('')

Compression

You can turn on or off compress to reduce file size. If you use the compression, then it really isn’t a json file anymore. Thus, other programs won’t be able to read it.

bag = BagWriter()           # or BagReader()
bag.use_compression = True  # or False (default)

Examples

See examples folder examples how to capture images and record them.

Change Log

2017-10-04

0.0.1

init

Software License

The MIT License (MIT)

Copyright (c) 2017 Kevin J. Walchko

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.