MDF4¶
asammdf tries to emulate the mdf structure using Python builtin data types.
The header attibute is an OrderedDict that holds the file metadata.
The groups attribute is a dictionary list with the following keys:
data_group : DataGroup object
channel_group : ChannelGroup object
channels : list of Channel objects with the same order as found in the mdf file
channel_conversions : list of ChannelConversion objects in 1-to-1 relation with the channel list
channel_sources : list of SourceInformation objects in 1-to-1 relation with the channels list
data_block : DataBlock object
texts : dictionay containing TextBlock objects used throughout the mdf
channels : list of dictionaries that contain TextBlock objects ralated to each channel
- name_addr : channel name
- comment_addr : channel comment
channel group : list of dictionaries that contain TextBlock objects ralated to each channel group
- acq_name_addr : channel group acquisition comment
- comment_addr : channel group comment
conversion_tab : list of dictionaries that contain TextBlock objects related to TABX and RTABX channel conversions
- text_{n} : n-th text of the VTABR conversion
- default_addr : default text
conversions : list of dictionaries that containt TextBlock obejcts related to channel conversions
- name_addr : converions name
- unit_addr : channel unit_addr
- comment_addr : converison comment
- formula_addr : formula text; only valid for algebraic conversions
sources : list of dictionaries that containt TextBlock obejcts related to channel sources
- name_addr : source name
- path_addr : source path_addr
- comment_addr : source comment
The file_history attribute is a list of (FileHistory, TextBlock) pairs .
The channel_db attibute is a dictionary that holds the (data group index, channel index) pair for all signals. This is used to speed up the get_signal_by_name method.
The master_db attibute is a dictionary that holds the channel index of the master channel for all data groups. This is used to speed up the get_signal_by_name method.
API¶
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class
asammdf.mdf4.
MDF4
(name=None, load_measured_data=True, compression=False, version='4.00')¶ If the name exist it will be loaded otherwise an empty file will be created that can be later saved to disk
Parameters: name : string
mdf file name
load_measured_data : bool
load data option; default True
- if True the data group binary data block will be loaded in RAM
- if False the channel data is read from disk on request
compression : bool
compression option for data group binary data block; default False
version : string
mdf file version (‘4.00’, ‘4.10’, ‘4.11’); default ‘4.00’
Attributes
name (string) mdf file name groups (list) list of data groups header (HeaderBlock) mdf file header file_history (list) list of (FileHistory, TextBlock) pairs comment (TextBlock) mdf file comment identification (FileIdentificationBlock) mdf file start block load_measured_data (bool) load measured data option compression (bool) measured data compression option version (int) mdf version channels_db (dict) used for fast channel access by name; for each name key the value is a (group index, channel index) tuple masters_db (dict) used for fast master channel access; for each group index key the value is the master channel index Methods
append
attach
extract_attachment
get
info
remove
save
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append
(signals, source_info='Python')¶ Appends a new data group.
Parameters: signals : list
list on Signal objects
acquisition_info : str
acquisition information; default ‘Python’
Examples
>>> # case 1 conversion type None >>> s1 = np.array([1, 2, 3, 4, 5]) >>> s2 = np.array([-1, -2, -3, -4, -5]) >>> s3 = np.array([0.1, 0.04, 0.09, 0.16, 0.25]) >>> t = np.array([0.001, 0.002, 0.003, 0.004, 0.005]) >>> names = ['Positive', 'Negative', 'Float'] >>> units = ['+', '-', '.f'] >>> info = {} >>> s1 = Signal(samples=s1, timstamps=t, unit='+', name='Positive') >>> s2 = Signal(samples=s2, timstamps=t, unit='-', name='Negative') >>> s3 = Signal(samples=s3, timstamps=t, unit='flts', name='Floats') >>> mdf = MDF4('new.mf4') >>> mdf.append([s1, s2, s3], 'created by asammdf v1.1.0') >>> # case 2: VTAB conversions from channels inside another file >>> mdf1 = MDF4('in.mf4') >>> ch1 = mdf1.get("Channel1_VTAB") >>> ch2 = mdf1.get("Channel2_VTABR") >>> sigs = [ch1, ch2] >>> mdf2 = MDF4('out.mf4') >>> mdf2.append(sigs, 'created by asammdf v1.1.0')
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attach
(data, file_name=None, comment=None, compression=True, mime='application/octet-stream')¶ attach embedded attachment as application/octet-stream
Parameters: data : bytes
data to be attached
file_name : str
string file name
comment : str
attachment comment
compression : bool
use compression for embedded attachment data
mime : str
mime type string
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extract_attachment
(index)¶ extract attachemnt index data. If it is an embedded attachment, then this method creates the new file according to the attachemnt file name information
Parameters: index : int
attachment index
Returns: data : bytes | str
attachment data
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get
(name=None, group=None, index=None, raster=None, samples_only=False)¶ Gets channel samples. Channel can be specified in two ways:
using the first positional argument name
- if there are multiple occurances for this channel then the group argument can be used to select a specific group.
- if there are multiple occurances for this channel and the group argument is None then a warning is issued
using the group number (keyword argument group) and the channel number (keyword argument index). Use info method for group and channel numbers
If the raster keyword argument is not None the output is interpolated accordingly
Parameters: name : string
name of channel
group : int
0-based group index
index : int
0-based channel index
raster : float
time raster in seconds
samples_only : bool
if True return only the channel samples as numpy array; if False return a Signal object
Returns: vals, t, unit, conversion : (numpy.array, numpy.array, string, dict | None)
The conversion is None exept for the VTAB and VTABR conversions. The conversion keys are:
for TABX conversion:
- raw - numpy.array for X-axis
- phys - numpy.array of strings for Y-axis
- type - conversion type = CONVERSION_TYPE_TABX
- default - default bytes value
for RTABX conversion:
- lower - numpy.array for lower range
- upper - numpy.array for upper range
- phys - numpy.array of strings for Y-axis
- type - conversion type =
- default - default bytes value
The conversion information can be used by the append method for the info argument
Raises: MdfError :
* if the channel name is not found
* if the group index is out of range
* if the channel index is out of range
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info
()¶ get MDF information as a dict
Examples
>>> mdf = MDF4('test.mdf') >>> mdf.info()
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remove
(group=None, name=None)¶ Remove data group. Use group or name keyword arguments to identify the group’s index. group has priority
Parameters: name : string
name of the channel inside the data group to be removed
group : int
data group index to be removed
Examples
>>> mdf = MDF4('test.mdf') >>> mdf.remove(group=3) >>> mdf.remove(name='VehicleSpeed')
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save
(dst=None)¶ Save MDF to dst. If dst is None the original file is overwritten