使用 MDF 事件
此示例说明如何从 MDF 文件中读取事件并使用事件过滤数据。
查看 MDF 文件中的所有事件
使用 mdfInfo 与文件名查看 MDF 文件的元数据和事件。
fileInfo = mdfInfo("VehicleDataWithEvents.mf4")fileInfo =
MDFInfo with properties:
File Details
Name: "VehicleDataWithEvents.mf4"
Path: "/tmp/Bdoc25b_2988451_1430519/tpe4ace63d/vnt-ex41269135/VehicleDataWithEvents.mf4"
Author: ""
Department: ""
Project: ""
Subject: ""
Comment: "Example file demonstrating workflows of reading events."
Version: "4.10"
InitialTimestamp: 2024-04-23 18:35:45.000000000
Creator Details
ProgramIdentifier: "MDF4Lib"
CreatorVendorName: ""
CreatorToolName: ""
CreatorToolVersion: "1.0"
CreatorUserName: ""
CreatorComment: "created"
File Contents
Attachment: [0×7 table]
ChannelGroupCount: 2
Event: [8×8 eventtable]
Event 属性包含 MDF 文件中所有事件的事件表。
fileEvents = fileInfo.Event
fileEvents = 8×8 eventtable
Event Labels Variable: Name
Event Lengths Variable: <instantaneous>
Time Name Comment Type Cause ScopeType GroupNumber RangeType LinkAddress
________ ________________ ________________________________________________________ __________________ ______ ____________ ___________ _________ ___________
0 sec "USER COMMENT" "Logging Vehicle Data 12/24/23" Marker User File NaN Point ""
1 sec "REC BEGIN" "Recording has started successfully." Recording Tool File NaN Begin "0x1C80"
1.2 sec "REC INTERRUPT" "Recording was interrupted." RecordingInterrupt Script ChannelGroup 1 Point ""
8.5 sec "USER REC BEGIN" "User-initiated subrecording start." Recording User ChannelGroup 1 Begin "0x1EC8"
10 sec "TIME TRIGGER" "Time min threshold trigger of 10 seconds has been hit." Trigger Script ChannelGroup 2 Point ""
11.5 sec "USER REC END" "User-initiated subrecording end." Recording User ChannelGroup 1 End "0x1EC8"
14.1 sec "RPM TRIGGER" "RPM max threshold trigger of 1500 has been hit." Trigger Script ChannelGroup 1 Point ""
15 sec "REC END" "Recording has stopped successfully." Recording Tool File NaN End "0x1C80"
每个事件都有一个时间戳和 8 个元数据值。
ScopeType值表示事件是应用于特定通道组还是应用于整个文件。GroupNumber值表示事件作用域限于的特定通道组。事件可以在某个时间点发生，也可以在一段时间内发生。
RangeType值表示事件是发生在某个时间点，标记范围的开始，还是标记范围的结束。LinkAddress值用于链接对应的范围事件。一对开始和结束范围事件共用相同的LinkAddress值，该值表示开始事件的地址。
从 MDF 文件中读取所有数据和事件
从 MDF 文件中读取所有数据和事件的最简单方法是只使用文件名调用 mdfRead 函数。每个时间表表示从对应的通道组读取的数据。每个时间表包含一个事件表，该事件表表示作用域限于对应通道组的文件级事件和通道组级事件。
data = mdfRead("VehicleDataWithEvents.mf4")data=2×1 cell array
{160×3 timetable}
{ 16×3 timetable}
data{1}ans=160×3 timetable with 7 events
t EngineRPM Throttle OutputTorque
_______ _________ ________ ____________
USER COMMENT 0 sec 41 7 34
0.1 sec 10 9.5 25
0.2 sec 98 9 14
0.3 sec 94 6.5 48
0.4 sec 121 9 15
0.5 sec 141 7.5 47
0.6 sec 87 9 47
0.7 sec 74 5.5 10
0.8 sec 172 6 29
0.9 sec 106 12.5 54
REC BEGIN 1 sec 147 11 31
1.1 sec 148 14.5 23
REC INTERRUPT 1.2 sec 187 15 47
1.3 sec 224 9.5 24
1.4 sec 162 10 37
1.5 sec 214 8.5 26
⋮
通过访问时间表的 Events 属性来检索附加到时间表的事件。
chanGrp1Events = data{1}.Properties.EventschanGrp1Events = 7×8 eventtable
Event Labels Variable: Name
Event Lengths Variable: <instantaneous>
Time Name Comment Type Cause ScopeType GroupNumber RangeType LinkAddress
________ ________________ _________________________________________________ __________________ ______ ____________ ___________ _________ ___________
0 sec "USER COMMENT" "Logging Vehicle Data 12/24/23" Marker User File NaN Point ""
1 sec "REC BEGIN" "Recording has started successfully." Recording Tool File NaN Begin "0x1C80"
1.2 sec "REC INTERRUPT" "Recording was interrupted." RecordingInterrupt Script ChannelGroup 1 Point ""
8.5 sec "USER REC BEGIN" "User-initiated subrecording start." Recording User ChannelGroup 1 Begin "0x1EC8"
11.5 sec "USER REC END" "User-initiated subrecording end." Recording User ChannelGroup 1 End "0x1EC8"
14.1 sec "RPM TRIGGER" "RPM max threshold trigger of 1500 has been hit." Trigger Script ChannelGroup 1 Point ""
15 sec "REC END" "Recording has stopped successfully." Recording Tool File NaN End "0x1C80"
data{2}ans=16×3 timetable with 4 events
t VehicleSpeed Brake Gear
______ ____________ _____ ____
USER COMMENT 0 sec 82 0 1
REC BEGIN 1 sec 97 1 2
2 sec 45 1 1
3 sec 58 1 0
4 sec 42 0 3
5 sec 146 1 1
6 sec 155 1 0
7 sec 130 0 0
8 sec 110 0 3
9 sec 161 1 3
TIME TRIGGER 10 sec 153 0 2
11 sec 134 0 3
12 sec 160 1 2
13 sec 159 0 1
14 sec 198 0 1
REC END 15 sec 157 1 0
chanGrp2Events = data{2}.Properties.EventschanGrp2Events = 4×8 eventtable
Event Labels Variable: Name
Event Lengths Variable: <instantaneous>
Time Name Comment Type Cause ScopeType GroupNumber RangeType LinkAddress
______ ______________ ________________________________________________________ _________ ______ ____________ ___________ _________ ___________
0 sec "USER COMMENT" "Logging Vehicle Data 12/24/23" Marker User File NaN Point ""
1 sec "REC BEGIN" "Recording has started successfully." Recording Tool File NaN Begin "0x1C80"
10 sec "TIME TRIGGER" "Time min threshold trigger of 10 seconds has been hit." Trigger Script ChannelGroup 2 Point ""
15 sec "REC END" "Recording has stopped successfully." Recording Tool File NaN End "0x1C80"
使用事件过滤数据
要基于事件过滤 MDF 数据，请使用 eventfilter。创建通道组 1 数据的子集，其中包含与某事件共享时间戳的采样。
EF = eventfilter(data{1})EF =
eventfilter with no constraints and no selected variables
<unconstrained>
VariableNames: Time, Name, Comment, Type, Cause, ScopeType, GroupNumber, Range…
dataFilteredToEventTimestamps = data{1}(EF, :)dataFilteredToEventTimestamps=7×3 timetable with 7 events
t EngineRPM Throttle OutputTorque
________ _________ ________ ____________
USER COMMENT 0 sec 41 7 34
REC BEGIN 1 sec 147 11 31
REC INTERRUPT 1.2 sec 187 15 47
USER REC BEGIN 8.5 sec 896 44.5 121
USER REC END 11.5 sec 1158 59.5 160
RPM TRIGGER 14.1 sec 1503 75.5 172
REC END 15 sec 1519 80 176
创建通道组 1 数据的子集，其中包含用户启动的记录开始事件和用户启动的记录结束事件之间的采样。
TR = timerange(EF.Name == "USER REC BEGIN", EF.Name == "USER REC END")
TR = timetable timerange subscript: Select timetable rows with event times in the half-open interval: Starting at, including: Name == "USER REC BEGIN" Ending at, but excluding: Name == "USER REC END" See Select Times in Timetable.
dataFilteredToUserRecEventTimeRange = data{1}(TR, :)dataFilteredToUserRecEventTimeRange=30×3 timetable with 7 events
t EngineRPM Throttle OutputTorque
_______ _________ ________ ____________
USER REC BEGIN 8.5 sec 896 44.5 121
8.6 sec 935 46 105
8.7 sec 912 47.5 103
8.8 sec 961 52 110
8.9 sec 941 45.5 138
9 sec 957 51 132
9.1 sec 999 50.5 103
9.2 sec 920 46 95
9.3 sec 999 47.5 131
9.4 sec 941 56 99
9.5 sec 973 49.5 130
9.6 sec 1042 53 134
9.7 sec 996 55.5 104
9.8 sec 1012 51 117
9.9 sec 1044 50.5 138
10 sec 1076 59 118
⋮
可视化包含事件的数据
使用 stackedplot 可视化 MDF 数据，其中事件标记为垂直线。
stackedplot(data{1})
