dwdat2py 0.2.0

Python wrappers around functions in Dewesoft DWDataReaderLib shared library

DEWESoft, a company making hardware for data acquisition also provide software applications (Windows) for working with data sets produced with the hardware. Files are in their proprietary formats such as .d7d, .d7z or .dxd. To work with the same data using a programming language like Python it is necessary to first convert them to a portable format such as text. To get around this extra step, DEWESoft provide a shared library called DWDataReaderLib.

dwdat2py is a python package with wrappers around the functions provided in DWDataReaderLib.

Installation

Using pip

pip install dwdat2py

Installing from source

Clone the repo with git clone https://github.com/tomnor/dwdat2py.git, cd into dwdat2py directory (the directory with the setup.py file) and say

python setup.py install

or do

pip install .

Get the library file(s) and prepare for use

The library files are provided by DEWESoft as non-free binary blobs and they are not provided with an installation of dwdat2py. The library pack can be obtained gratis at https://download.dewesoft.com/list/developers where one has to register for an account to get it. Once logged in, find a button “Dewesoft Data Reader Library”, enabling to download a zip file (DWDataReader.zip) with the library.

Unpack that archive and put the library files for your system into a directory of choice, probably on the machine you work on. There is only one file needed, for example the DWDataReaderLib64.so or the DWDataReaderLib64.dll. There are a number of duplicates, the tree of the archive look like this:

DWDataReader_v4_2_0_11
├── DWDataReaderv.doc
├── DWDataReaderv.doc.txt
├── EULA-DWDataReader.pdf
├── Linux32&64 C
│   ├── DWDataReaderExample.c
│   ├── DWDataReaderLib64.so
│   ├── DWDataReaderLib.so
│   ├── DWLoadLib.c
│   ├── DWLoadLib.h
│   └── Red Hat 5
├── Win32&64 C
│   ├── DReader_c_win.exe
│   ├── DReader_c_win.vcxproj
│   ├── DWDataReaderExample.c
│   ├── DWDataReaderLib64.dll
│   ├── DWDataReaderLib.dll
│   ├── DWLoadLib.c
│   └── DWLoadLib.h

...

Followed by a number of other language example directories. However, all the DWDataReaderLib64.dll files seem to be copies, so just pick one of them if on Windows, else pick one of the .so files.

There are three ways to tell dwdat2py where the library is:

• Set an environment variable DEWELIBDIR to the directory where the library file are put.

• Use a configuration file called dewelibdir optionally with the extension .txt or .pth. Enter a line in it pointing to the library directory. Empty lines or lines starting with # are ignored. Put that in either ~/.config (Gnu/Linux) or in ~ on Windows. In any case, os.path.expanduser() is used to figure out the location of ~.

• Or finally resort to setting dwdat2py.DEWELIBDIR to point to the directory, (prior to importing dwdat2py.wrappers)

There is a “competing” package called dwdatareader which provide the library files with its distribution, so alternatively get the library file from there or try that package out as well [1].

Usage

from dwdat2py import wrappers as dw

dw.init()
dw.open_data_file('dat1')
# ... other functions to get at data in dat1 ...
dw.close_data_file()
dw.open_data_file('dat2')
# ... other functions to get at data in dat2 ...
dw.close_data_file() # work is done for now
dw.de_init()
# optionally init() again for a new session.

The calls init() and de_init() must be called first and last respectively. Make sure open_data_file(...) is called successfully before close_data_file(...), else don’t call close_data_file.

The highest level function for now in this package is this:

def channel_reduced(channel, reduction, encoding=None):
    """Return a flat list of data for channel reduced to reduction.

    Parameters
    ----------

    channel : int or str
        Either the channel index or the channel name.

    reduction : int
        One of the following
        time_stamp = 0
        ave = 1
        min = 2
        max = 3
        rms = 4

    encoding : str
        encoding to pass to `get_channel_list()`, which see.

    Wraps:
        Nothing explicit. This is a support function to simplify getting
        reduced data from a channel.

    """

And if you happen to know the index or name of the channels, this function should suffice to get at the data, channel by channel. Else you would need to call some helper functions first to prepare for this call.

Access to the wrappers module is optionally provided as a context manager:

@contextmanager
def wrappersimport(fn, fsencoding=None):
    """Provide context access to the wrappers module.

    Return a handle to the wrappers module in a context manager and file
    `fn` (str) opened for operations (a .dxd file for example).
    Initialization and deinitialization is provided by this context
    manager, as well as opening and closing the file.

    The file information resulting from opening the file is available as
    a module level variable `fileinfo`, (`handle.fileinfo`).

    The function that `wrappers.open_data_file` wraps require bytes as
    file name. `fsencoding` is used in the call to
    `wrappers.open_data_file` but is hopefully not necessary to specify
    since os.fsencode() is used by default.

    Example usage:

    >>> import dwdat2py
    >>> with dwdat2py.wrappersimport(fn) as wi:
    ...    print(wi.fileinfo)
    ...    chlist = wi.get_channel_list(encoding='latin1')
    ...    for chinfo in chlist:
    ...        # print the average values from each channel (1)
    ...        print(wi.channel_reduced(chinfo.index, 1, encoding='latin1'))
    ...    # get the "time stamps" (0)
    ...    time = wi.channel_reduced(chlist[0].index, 0, encoding='latin1')

    As with importing the wrappers module in the standard way, this will
    fail if the shared library is not found.

    """

Contribute

Please report bugs and send suggestions or patches to the author. Or make an issue or pull request on the repo home at Github

[1]

dwdatareader solves the same problem but with higher level of abstraction to the library functions.