mirror of
https://github.com/pybricks/pybricks-api.git
synced 2026-09-11 17:14:41 +00:00
Laurens Valk
05ea3654ec
Now that the EV3 starter guide is back, we can refer to it instead of including a duplicate image of the ev3dev file browser.
90 lines
2.7 KiB
ReStructuredText
90 lines
2.7 KiB
ReStructuredText
:mod:`tools <pybricks.tools>` -- Timing and Data logging
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========================================================
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.. automodule:: pybricks.tools
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:no-members:
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.. autofunction:: wait
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.. autoclass:: pybricks.tools.StopWatch
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:no-members:
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.. automethod:: pybricks.tools.StopWatch.time
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.. automethod:: pybricks.tools.StopWatch.pause
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.. automethod:: pybricks.tools.StopWatch.resume
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.. automethod:: pybricks.tools.StopWatch.reset
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.. autoclass:: pybricks.tools.DataLog
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:no-members:
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.. automethod:: pybricks.tools.DataLog.log
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By default, this class creates a ``csv`` file on the EV3 brick with the
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name ``log`` and the current date and time. For example, if you
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use this class on 13 February 2020 on 10:07 and 44.431260
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seconds, the file is called ``log_2020_02_13_10_07_44_431260.csv``.
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See :ref:`managing files on the EV3 <managefiles>` to learn how to upload
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the log file back to your computer.
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.. toggle-header::
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:header: **Show/hide example: Logging and visualizing measurements**
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**Example**
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This example shows how to log the angle of a rotating wheel as time passes.
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.. literalinclude:: ../../pybricks-projects/snippets/ev3/datalog/main.py
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In this example, the generated file has the following contents::
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time, angle
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3, 0
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108, 6
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212, 30
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316, 71
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419, 124
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523, 176
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628, 228
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734, 281
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838, 333
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942, 385
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When you upload the file to your computer as shown above, you can open it
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in a spreadsheet editor. You can then generate a graph of the data, as
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shown in :numref:`fig_datalog_graph`.
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In this example, we see that the motor angle changes slowly at first. Then
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the angle begins to change faster, and the graph becomes a straight line.
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This means that the motor has reached a constant speed. You can verify that
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the angle increases by 500 degrees per second.
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.. _fig_datalog_graph:
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.. figure:: ../api/images/datalog_graph.png
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:width: 100 %
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Original file contents (left) and a generated graph (right).
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.. toggle-header::
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:header: **Show/hide example: Using the optional arguments**
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**Example**
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This example shows how to log data beyond just numbers. It also shows how
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you can use the optional arguments of the ``DataLog`` class to choose the
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file name and extension.
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In this example, ``timestamp=False``, which means that the date and time
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are not added to the file name. This can be convenient because the file
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name will always be the same. However, this means that the contents of
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``my_file.txt`` will be overwritten every time you run this script.
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.. literalinclude:: ../../pybricks-projects/snippets/ev3/datalog_extra/main.py
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