mdfRead
Description
reads all data for all channels from the specified MDF file, and assigns the output
to the cell array data
= mdfRead(mdfFileName
)data
. The output cell array contains a
timetable for each channel group of returned data, where the cell array index
corresponds to the sequence of returned channel groups.
allows name-value arguments to filter on specific channels and channel groups,
request metadata, and apply other options.data
= mdfRead(___,Name=Value
)
Examples
Read All Data from MDF File
Read all available data from the MDF file.
data = mdfRead("VehicleData.mf4"); head(data{1}) % First timetable in returned cell array.
time EngineRPM Brake Throttle Gear ImpellerTorque OutputTorque TransmissionRPM VehicleSpeed ________ _________ _____ ________ ____ ______________ ____________ _______________ ____________ 0 sec 1000 0 60 1 52.919 282.65 0 0 0.04 sec 1383.3 0 59.946 1 101.4 532.63 13.593 0.30047 0.08 sec 1685.4 0 59.893 1 150.76 776.41 35.847 0.7924 0.12 sec 1907.2 0 59.839 1 193.42 973.15 65.768 1.4538 0.16 sec 2062 0 59.785 1 227.02 1117.6 101.53 2.2443 0.2 sec 2161.2 0 59.732 1 251.11 1212.8 141.45 3.1268 0.24 sec 2221.4 0 59.678 1 267.24 1264.3 183.86 4.0644 0.28 sec 2257.2 0 59.624 1 276.35 1271.2 227.25 5.0234
Read Raw Data
Read raw data without applying any conversion rules.
dataraw = mdfRead("VehicleData.mf4",ReadRaw=true);
Read All Data from Specified Channels
Read all available data from the MDF file for specified channel names.
data = mdfRead("VehicleData.mf4",Channel=["*Torque" "*Rate"]);
Read Range of Data from Specified Index Values
Read a range of data from the MDF file using indexing to specify the start and end.
data = mdfRead("VehicleData.mf4",IndexRange=[65,128]);
Read Range of Data from Specified Time Values
Read a range of data from the MDF file over a specified span of time.
data = mdfRead("VehicleData.mf4",TimeRange=seconds([0,30]));
Read Data from Channel Table
Read data from channels identified by the
mdfChannelInfo
function.
Get a table of channels and display their names and group numbers.
chanInfoTable = mdfChannelInfo("VehicleData.mf4",Channel=["*Torque","*Speed"]); chanInfoTable(:,1:3) % Partial display.
ans = 3×3 table Name GroupNumber GroupNumSamples ________________ ___________ _______________ "ImpellerTorque" 1 751 "OutputTorque" 1 751 "VehicleSpeed" 1 751
Read data from specified channels.
data = mdfRead("VehicleData.mf4",Channel=chanInfoTable); head(data{1}) % View top of data timetable.
time ImpellerTorque OutputTorque VehicleSpeed ________ ______________ ____________ ____________ 0 sec 52.919 282.65 0 0.04 sec 101.4 532.63 0.30047 0.08 sec 150.76 776.41 0.7924 0.12 sec 193.42 973.15 1.4538 0.16 sec 227.02 1117.6 2.2443 0.2 sec 251.11 1212.8 3.1268 0.24 sec 267.24 1264.3 4.0644 0.28 sec 276.35 1271.2 5.0234
Read Data and Metadata
Read data from an MDF file into a timetable, along with channel group metadata and channel metadata.
Read all data from an MDF file with its metadata, then view the metadata of the first channel group.
dataGrp1 = mdfRead("VehicleData.mf4",IncludeMetadata=true);
dataGrp1{1}.Properties.CustomProperties
ans = CustomProperties with properties: ChannelGroupAcquisitionName: "" ChannelGroupComment: "Simulation of an automatic transmission controller during passing maneuver." ChannelGroupSourceName: "" ChannelGroupSourcePath: "" ChannelGroupSourceComment: "" ChannelGroupSourceType: Unspecified ChannelGroupSourceBusType: Unspecified ChannelGroupSourceBusChannelNumber: 0 ChannelDisplayName: ["" "" "" "" "" "" "" ""] ChannelComment: ["" "" "" "" "" "" "" ""] ChannelUnit: ["rpm" "ft*lbf" "%" "" "ft*lbf" "ft*lbf" "rpm" "mph"] ChannelType: [FixedLength FixedLength FixedLength FixedLength FixedLength FixedLength … ] ChannelDataType: [RealLittleEndian IntegerUnsignedLittleEndian RealLittleEndian … ] ChannelNumBits: [64 8 64 8 64 64 64 64] ChannelComponentType: [None None None None None None None None] ChannelCompositionType: [None None None None None None None None] ChannelSourceName: ["" "" "" "" "" "" "" ""] ChannelSourcePath: ["" "" "" "" "" "" "" ""] ChannelSourceComment: ["" "" "" "" "" "" "" ""] ChannelSourceType: [Unspecified Unspecified Unspecified Unspecified Unspecified Unspecified … ] ChannelSourceBusType: [Unspecified Unspecified Unspecified Unspecified Unspecified Unspecified … ] ChannelSourceBusChannelNumber: [0 0 0 0 0 0 0 0] ChannelReadOption: [All All All All All All All All]
Input Arguments
mdfFileName
— MDF file name
string | char vector
MDF file name, specified as a string or character vector, including the necessary full or relative path. You can use a URL to specify a file on a remote server.
Depending on the location you are accessing,
mdfFileName
can take one of these forms.
Location | Form | ||||||||
---|---|---|---|---|---|---|---|---|---|
Current folder or MATLAB® path | To access a file in the current folder or MATLAB path, specify the
name of the file in Example:
| ||||||||
Other folders | To access a file in a folder other than the current folder, specify
the full or relative path name in
Example:
Example:
| ||||||||
Remote locations | To access a file in a remote location,
Based on the remote location,
For more information, see Work with Remote Data. Example:
|
Data Types: string
| char
Name-Value Arguments
Specify optional pairs of arguments as
Name1=Value1,...,NameN=ValueN
, where Name
is
the argument name and Value
is the corresponding value.
Name-value arguments must appear after other arguments, but the order of the
pairs does not matter.
Before R2021a, use commas to separate each name and value, and enclose
Name
in quotes.
Example: GroupNumber=2
GroupNumber
— Channel group number
numeric
Channel group number, specified as a numeric scalar for one group, or numeric vector for multiple groups. The function returns data from channels found only in these specified channel groups. If unspecified, data for all channel groups are returned.
Example: GroupNumber=[1,2]
Data Types: single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
Channel
— Channel names
string | char | cell | table
Channel names to return data from, specified as a string or array of strings, or as a character vector or cell array of character vectors. Use an array to match on any of multiple channel names. Wildcards allow partial matching. If unspecified, data for all channels are returned.
You can also specify channels using a table generated by the mdfChannelInfo
(Vehicle Network Toolbox) function. When using a table to specify
channels, the GroupNumber
option is ignored.
Example: Channel=["*Rate","*Speed"]
Data Types: string
| char
| cell
| table
AbsoluteTime
— Return absolute timestamps
false
(default) | true
Return absolute timestamps, specified as true
or
false
. If specified true
, the
returned timetable has absolute timestamps in datetime. If specified
false
, the returned timetable has relative
timestamps in duration, elapsed from the initial timestamp of the file.
The default value is false
, to return relative
timestamps.
Example: AbsoluteTime=true
Data Types: logical
TimeRange
— Time interval of data
datetime vector | duration vector
Start time and end time of an interval to read data from, specified as
a 2-element vector. If AbsoluteTime=true
, specify
TimeRange
as a datetime vector. If
AbsoluteTime=false
(default), specify
TimeRange
as a duration vector. If unspecified,
all data samples are read. You cannot combine this option with
IndexRange
.
Example: TimeRange=seconds([0,60])
Data Types: datetime
| duration
IndexRange
— Start and end indices of data to read
numeric vector
Start index and end index of the interval to read data from, specified
as a 2-element vector. The indices are inclusive. If unspecified, all
data samples are read. You cannot combine this option with
TimeRange
.
Example: IndexRange=[65:128]
Data Types: single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
ReadRaw
— Read raw data values
false
(default) | true
Read raw data values, specified as true
or
false
. If specified true
, data
are read as raw values. If specified false
, data are
read as physical values. The default value is
false
.
Example: ReadRaw=true
Data Types: logical
IncludeMetadata
— Include metadata for channel groups and channels
false
(default) | true
Include channel group metadata and channel metadata in the results,
specified as true
or false
. If
true
, metadata are added as custom properties to
each returned timetable. Metadata are included only for output
timetables that are not empty. If false
, metadata are
not included. The default value is false
.
Because mdfRead
returns a timetable for each
channel group, metadata for this channel group and all channels in this
group are added to the timetable as custom properties. You can access
the timetable tt
custom properties at
tt.Properties.CustomProperties
.
The mdfRead
function takes longer to execute when
metadata are included.
Example: IncludeMetadata=true
Data Types: logical
IncludeEvents
— Attach event table to output
true
(default) | false
Attach event table to each channel group output timetable, specified
as true
or false
. When
true
(default) the function attaches an
eventtable to each timetable output, accessible in the returned
timetable's properties at
tt.Properties.Events
.
For more information, see the example Work with MDF Events (Vehicle Network Toolbox).
Example: IncludeEvents=false
Data Types: logical
ValidityRule
— Instruction for reading validity data
"include"
(default) | "ignore"
| "replace"
Instruction for reading validity data from MDF file, specified as one of the following string values:
"include"
(default) — Read validity data and store it in the returned timetable's custom property attt.Properties.CustomProperties.Validity
."ignore"
— Do not read validity data."replace"
— Read validity data and replace all invalid samples with the MATLABmissing
value. All integer channels containing invalid samples are converted to double.
For more information, see the example Read Validity Data from MDF Files (Vehicle Network Toolbox).
Example: ValidityRule="replace"
Data Types: char
| string
Output Arguments
data
— Channel data
cell array of timetables
Channel data, returned as a cell array of timetables, with a timetable for each group.
Limitations
mdfRead
does not support array channels with more than 3 dimensions.Reading from a nested composition of channels is not supported. You can read from simple structure channels or array channels, but not from a structure or array of composed signals.
mdfRead
does not support reading from channels with partial conversion rules.
Version History
Introduced in R2023aR2024b: Support for Validity Data and Events
mdfRead
now accepts the following name-value
arguments:
ValidityRule
with a string value.IncludeEvents
with a logical value.
R2023a: Support for Remote File URLs
You can directly access MDF file data stored at remote locations, including Amazon S3, Azure® Blob Storage, and HDFS.
See Also
Functions
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