# Creating logs

Transforming your raw data into an event log object is one of the most challenging tasks in process analysis. On this page, we cover all the possible situations and challenges that you can encounter.

• Case: The subject of your process, e.g. a customer, an order, a patient.
• Activity: A step in your process, e.g. receive order, sent payment, perform MRI SCAN, etc.
• Activity instance: The execution of a specific step for a specific case.
• Event: A registration connected to an activity instance, characterized by a single timestamp. E.g. the start of Perform MRI SCAN for Patient X.
• Resource: A person or machine that is related to the execution of (part of) an activity instance. E.g. the radiologist in charge of our MRI SCAN.
• Lifecycle status: An indication of the status of an activity instance connect to an event. Typical values are start, complete. Other possible values are schedule, suspend, resume, etc.
• Trace: A sequence of activities. The activity instances that belong to a case will result to a specific trace when ordered by the time each instance occurred.

## Logs: eventlog vs activitylog

bupaR supports two different kinds of log formats, both of which are an extension on R data.frame:

• eventlog: Event logs are created from data.frame in which each row represents a single event. This means that it has a single timestamp.
• activitylog: Activity logs are created from data.frame in which each row represents a single activity instances. This means it can has multiple timestamps, stored in different columns.

The data model below shows the difference between these two levels of observations, i.e. activity instances vs events.

The example below shows an excerpt of an event log containing 6 events. It can be seen that each event is linked to a single timestamp. As there can be more events within a single activity instance, each event also needs to be linked to a lifecycle status (here the registration_type). Furthermore, an activity instance identifier (handling_id) is needed to indicated which events belong to the same activity instances.

handling patient employee handling_id registration_type time
Registration 89 r1 89 start 2017-04-04 06:54:12
Registration 89 r1 89 complete 2017-04-04 09:08:36
Triage and Assessment 89 r2 589 start 2017-04-04 22:17:12
Triage and Assessment 89 r2 589 complete 2017-04-05 11:45:27
X-Ray 89 r5 1518 start 2017-04-05 20:55:30
X-Ray 89 r5 1518 complete 2017-04-06 04:16:10
Transactional lifecycle?
An event is an atomic registration related to an activity instance. It thus contains one (and only one) timestamp. Additionally, the event should include a reference to a lifecycle transition. More specifically, multiple events can describe different lifecycle transitions of a single activity instance. For example, one event might record when a surgery is scheduled, another when it is started, yet another when it is completed, etc.
The standard transactional lifecycle.

The table below show the same data as above, but now using the activitylog format. It can be seen that there are now just 3 rows instead of 6, but each row as 2 timestamps, representing 2 events. The lifecycle status represented by those timestamps is now the column names of those variables.

handling patient employee handling_id complete start
Registration 89 r1 89 2017-04-04 09:08:36 2017-04-04 06:54:12
Triage and Assessment 89 r2 589 2017-04-05 11:45:27 2017-04-04 22:17:12
X-Ray 89 r5 1518 2017-04-06 04:16:10 2017-04-05 20:55:30

As these examples show, both formats can often be used for representing the same process data. However, there are some important differences between them:

• the eventlog format has much more flexibility in terms of lifecycle. There is no limit to the number of events that can occur in a single activity instance. If your data contains lifecycle statuses such as suspend, resume or reassign, they can be recorded multiple times within a single activity instance. In the activitylog format, as each lifecycle gets is own column, it isn’t possible to have two events of the same lifecycle status in a single activity instance.
• the level of observation in an eventlog is an event. As a result, attribute values can be stored at the event level. In an activitylog, the level of observation is an activity instance. This means that all additional attributes that you have about your process should be at this higher level. For example, an activity instance can only be connected to a single resource in the activitylog format, whereas in an eventlog different events within the same activity instance can have different resources, of different values for any other attribute.
• because of the limited flexibility, an activitylog is easier to make, and typically closer to the format that your data is already in (see further below on how to construct log objects). As a result of this, there are many situations in which the analysis of an activitylog will be much faster compared to eventlog, where a lot of additional complexity needs to be taken into account.

## The right log for the job

Functionalities in bupaR core packages support both formats. 1 As such, the goal of your analysis does not impact the decision. Only the complexity of your data is important to make this decision. The precise format your raw data is in will further define the preparatory steps that are needed. We can distinguish between 3 typical scenarios. The flowchart below helps you on your way.

An activitylog is the best option when each row in your data is an activity instance, or when events belonging to the same activity instance have equal attribute values (e.g. all events are executed by the same resource). When these two criteria do not hold, you can create an eventlog object.

### Scenario 1

If each row in your data.frame is already an activity instance, the activitylog format is the best way to go. Consider the data sample below.

patient handling activity_started activity_ended
170 Blood test 2017-06-18 22:51:07 2017-06-19 03:01:11
170 Check-out 2017-06-20 03:48:37 2017-06-20 05:36:40
170 Discuss Results 2017-06-19 22:46:10 2017-06-20 01:44:29
170 MRI SCAN 2017-06-19 06:44:30 2017-06-19 11:40:53
170 Registration 2017-06-17 15:10:30 2017-06-17 16:31:58
170 Triage and Assessment 2017-06-17 16:31:58 2017-06-18 04:14:55

As each row contains multiple timestamps, i.e. activity_started and activity_ended, it is clear that each row represents an activity instance. Turning this dataset in an activitylog requires the following steps:

1. Timestamp variables should be named in correspondence with the standard Transactional lifecycle.
2. Timestamp variables should be of type Date or POSIXct.
3. Use the activitylog constructor function.
data %>%
# rename timestamp variables appropriately
dplyr::rename(start = activity_started,
complete = activity_ended) %>%
# convert timestamps to
convert_timestamps(columns = c("start", "complete"), format = ymd_hms) %>%
activitylog(case_id = "patient",
activity_id = "handling",
timestamps = c("start", "complete"))
## # Log of 12 events consisting of:
## 1 trace
## 1 case
## 6 instances of 6 activities
## 0 resources
## Events occurred from 2017-06-17 15:10:30 until 2017-06-20 05:36:40
##
## # Variables were mapped as follows:
## Case identifier:     patient
## Activity identifier:     handling
## Resource identifier:     employee
## Timestamps:      start, complete
##
## # A tibble: 6 × 5
##   patient handling              start               complete            .order
##   <chr>   <fct>                 <dttm>              <dttm>               <int>
## 1 170     Blood test            2017-06-18 22:51:07 2017-06-19 03:01:11      1
## 2 170     Check-out             2017-06-20 03:48:37 2017-06-20 05:36:40      2
## 3 170     Discuss Results       2017-06-19 22:46:10 2017-06-20 01:44:29      3
## 4 170     MRI SCAN              2017-06-19 06:44:30 2017-06-19 11:40:53      4
## 5 170     Registration          2017-06-17 15:10:30 2017-06-17 16:31:58      5
## 6 170     Triage and Assessment 2017-06-17 16:31:58 2017-06-18 04:14:55      6

Note that in case a resource identifier is available, this information can be added in the activitylog call.

### Scenario 2

If each row in your data.frame is an event, but all events that belong to the same activity instance share the same attribute values, the activitylog format is again the best way to go. Consider the data sample below.

patient handling employee handling_id registration_type time
59 Registration r1 59 started 2017-03-07 02:53:18
59 Triage and Assessment r2 559 started 2017-03-07 04:27:53
59 Registration r1 59 completed 2017-03-07 04:27:53
59 Triage and Assessment r2 559 completed 2017-03-07 18:45:53
59 Blood test r3 1027 started 2017-03-08 04:52:55
59 Blood test r3 1027 completed 2017-03-08 12:23:02
59 MRI SCAN r4 1264 started 2017-03-11 19:31:13
59 MRI SCAN r4 1264 completed 2017-03-12 01:24:26
59 Discuss Results r6 1793 started 2017-03-12 06:50:13
59 Check-out r7 2288 started 2017-03-12 08:49:18
59 Discuss Results r6 1793 completed 2017-03-12 08:49:18
59 Check-out r7 2288 completed 2017-03-12 10:24:35

The resource identifier (employee) has been added as an additional attribute. Note that though each row is an event, they can be grouped into activity instances using the handling_id column, which we will call the activity instance id. Using the latter, we can see that the resource attribute is the same within each activity instance, which allows us to create an activitylog. The steps to do so are the following.

1. Lifecycle variable should be named in correspondence with the standard Transactional lifecycle.
2. Timestamp variable should be of type Date or POSIXct.
3. Use the eventlog constructor function.
4. Convert to activitylog using to_activitylog for reduced memory usage and improved performance.
data %>%
# recode lifecycle variable appropriately
dplyr::mutate(registration_type = forcats::fct_recode(registration_type,
"start" = "started",
"complete" = "completed")) %>%
convert_timestamps(columns = "time", format = ymd_hms) %>%
eventlog(case_id = "patient",
activity_id = "handling",
activity_instance_id = "handling_id",
lifecycle_id = "registration_type",
timestamp = "time",
resource_id = "employee") %>%
to_activitylog() -> tmp_act

Note that the resource identifier is optional, and can be left out of the eventlog call if such an attribute does not exist in your data. If the activity instance id does not exist, some heuristics are available to generate it: [Missing activity instance identifier].

### Scenario 3

If each row is an event, and events of the same activity instance have differing attribute values, the flexibility of eventlog objects is required. Consider the data sample below.

patient handling employee handling_id registration_type time
182 Registration r1 182 started 2017-06-25 11:18:08
182 Registration r6 182 completed 2017-06-25 15:01:00
182 Triage and Assessment r7 682 started 2017-06-25 22:36:32
182 Triage and Assessment r2 682 completed 2017-06-26 16:03:00
182 X-Ray r5 1568 started 2017-06-28 07:03:55
182 X-Ray r5 1568 completed 2017-06-28 11:30:00
182 Discuss Results r7 1916 started 2017-07-02 11:16:08
182 Discuss Results r1 1916 completed 2017-07-02 14:19:52
182 Check-out r2 2411 started 2017-07-03 03:39:52
182 Check-out r6 2411 completed 2017-07-03 06:45:20

In this example, different resources (employees) sometimes perform the start and complete event of the same activity instance. Therefore, we resort to the eventlog format which has no problems storing this. The steps to take are the following:

1. Lifecycle variable should be named in correspondence with the standard Transactional lifecycle.
2. Timestamp variable should be of type Date or POSIXct.
3. Use the eventlog constructor function.
data %>%
# recode lifecycle variable appropriately
dplyr::mutate(registration_type = forcats::fct_recode(registration_type,
"start" = "started",
"complete" = "completed")) %>%
convert_timestamps(columns = "time", format = ymd_hms) %>%
eventlog(case_id = "patient",
activity_id = "handling",
activity_instance_id = "handling_id",
lifecycle_id = "registration_type",
timestamp = "time",
resource_id = "employee") 
## Warning in validate_eventlog(eventlog): The following activity instances are
## connected to more than one resource: 182,1916,2411,682
## # Log of 10 events consisting of:
## 1 trace
## 1 case
## 5 instances of 5 activities
## 5 resources
## Events occurred from 2017-06-25 11:18:08 until 2017-07-03 06:45:20
##
## # Variables were mapped as follows:
## Case identifier:     patient
## Activity identifier:     handling
## Resource identifier:     employee
## Activity instance identifier:    handling_id
## Timestamp:           time
## Lifecycle transition:        registration_type
##
## # A tibble: 10 × 7
##    patient handling           emplo…¹ handl…² regis…³ time                .order
##    <chr>   <fct>              <fct>   <chr>   <fct>   <dttm>               <int>
##  1 182     Registration       r1      182     start   2017-06-25 11:18:08      1
##  2 182     Registration       r6      182     comple… 2017-06-25 15:01:00      2
##  3 182     Triage and Assess… r7      682     start   2017-06-25 22:36:32      3
##  4 182     Triage and Assess… r2      682     comple… 2017-06-26 16:03:00      4
##  5 182     X-Ray              r5      1568    start   2017-06-28 07:03:55      5
##  6 182     X-Ray              r5      1568    comple… 2017-06-28 11:30:00      6
##  7 182     Discuss Results    r7      1916    start   2017-07-02 11:16:08      7
##  8 182     Discuss Results    r1      1916    comple… 2017-07-02 14:19:52      8
##  9 182     Check-out          r2      2411    start   2017-07-03 03:39:52      9
## 10 182     Check-out          r6      2411    comple… 2017-07-03 06:45:20     10
## # … with abbreviated variable names ¹​employee, ²​handling_id, ³​registration_type

Note that we need an eventlog irrespective of which attribute values are differing, i.e. it can be resources, but also any additional variables you have in your data set. For the special case of resource values, it might be that a different resource executing events in the same activity instance is a data quality issue. If so, some functions can help you to identify this issue: Inconsistent Resources.

Again, if the activity instance id does not exist, some heuristics are available to generate it: [Missing activity instance identifier].

## Typical problems

### Missing activity instance id

In order to be able to correlate events which belong to the same activity instance, an activity instance identifier is required. For example, in the data shown below, it is possible that a patient has gone through different surgeries, each with their own start- and complete event. The activity instance identifier will then allow to distinguish which events belong together and which do not. It is important to note that this instance identifier should be unique, also among different cases and activities.

patient activity timestamp status activity_instance
John Doe check-in 2017-05-10 08:33:26 complete 1
John Doe surgery 2017-05-10 08:53:16 start 2
John Doe surgery 2017-05-10 09:25:19 complete 2
John Doe treatment 2017-05-10 10:01:25 start 3
John Doe treatment 2017-05-10 10:35:18 complete 3
John Doe surgery 2017-05-10 10:41:35 start 4
John Doe surgery 2017-05-10 11:05:56 complete 4
John Doe check-out 2017-05-11 14:52:36 complete 5

If the activity instance identifier is not available you can use the assign_instance_id() function, which uses an heuristic to create the missing identifier. Alternatively, you can try to create the identifier on your own using dplyr::mutate() and other manipulation functions.

### Large Datasets and Validation

By default, bupaR validates certain properties of the activity instances that is supplied when creating an event log:

• a single activity instance identifier must not be connected to multiple cases,
• a single activity instance identifier must not be connected to multiple activity labels,

However, these checks are not efficient and may lead to considerable performance issues for large data frames. It is possible to deactivate the validation in case you already know that your data fulfills all the requirements, using the argument validate = FALSE when creating the eventlog. Note that when the activity instance id was created with the assign_instance_id() function, you can assume the above properties hold.

### Inconsistent Resources

Each event can contain the notion of a resource. It can be so that different events belonging to the same activity instance are executed by different resources, as in the eventlog below.

patient handling employee handling_id registration_type time .order
139 Registration r7 139 start 2017-05-17 08:37:35 1
139 Triage and Assessment r4 639 start 2017-05-17 10:33:49 2
139 Registration r1 139 complete 2017-05-17 10:33:49 3
139 Triage and Assessment r6 639 complete 2017-05-18 02:32:38 4
139 Blood test r6 1068 start 2017-05-18 23:10:39 5
139 Blood test r1 1068 complete 2017-05-19 03:57:40 6
139 MRI SCAN r2 1305 start 2017-05-19 07:57:18 7
139 MRI SCAN r2 1305 complete 2017-05-19 11:34:01 8
139 Discuss Results r7 1873 start 2017-05-19 17:20:52 9
139 Discuss Results r3 1873 complete 2017-05-19 20:41:58 10
139 Check-out r3 2368 start 2017-05-21 17:29:34 11
139 Check-out r4 2368 complete 2017-05-21 18:44:55 12

If you have a large dataset, and want to have an overview of the activity instances that have more than one resource connected to them, you can use the detect_resource_inconsistences() function.

log %>%
detect_resource_inconsistencies()
## # A tibble: 5 × 5
##   patient handling              handling_id complete start
##   <chr>   <fct>                 <chr>       <chr>    <chr>
## 1 139     Blood test            1068        r1       r6
## 2 139     Check-out             2368        r4       r3
## 3 139     Discuss Results       1873        r3       r7
## 4 139     Registration          139         r1       r7
## 5 139     Triage and Assessment 639         r6       r4

If you want to remove these inconsistencies, a quick fix is to merge the resource labels together with fix_resource_inconsistencies(). Note that this is not needed for eventlog, but it is for activitylog. While the creation of the eventlog will emit a warning when resource inconsistencies exist, this should mostly be seen as a data quality warning. That said, there might be analysis related to the counting of resources where such inconsistencies might lead to odd results.

log %>%
fix_resource_inconsistencies()
## *** OUTPUT ***
## A total of 5 activity executions in the event log are classified as inconsistencies.
## They are spread over the following cases and activities:
## # A tibble: 5 × 5
##   patient handling              handling_id complete start
##   <chr>   <fct>                 <chr>       <chr>    <chr>
## 1 139     Blood test            1068        r1       r6
## 2 139     Check-out             2368        r4       r3
## 3 139     Discuss Results       1873        r3       r7
## 4 139     Registration          139         r1       r7
## 5 139     Triage and Assessment 639         r6       r4
## Inconsistencies solved succesfully.
## # Log of 12 events consisting of:
## 1 trace
## 1 case
## 6 instances of 6 activities
## 6 resources
## Events occurred from 2017-05-17 08:37:35 until 2017-05-21 18:44:55
##
## # Variables were mapped as follows:
## Case identifier:     patient
## Activity identifier:     handling
## Resource identifier:     employee
## Activity instance identifier:    handling_id
## Timestamp:           time
## Lifecycle transition:        registration_type
##
## # A tibble: 12 × 7
##    patient handling           emplo…¹ handl…² regis…³ time                .order
##    <chr>   <fct>              <chr>   <chr>   <fct>   <dttm>               <int>
##  1 139     Registration       r1 - r7 139     start   2017-05-17 08:37:35      1
##  2 139     Triage and Assess… r6 - r4 639     start   2017-05-17 10:33:49      2
##  3 139     Registration       r1 - r7 139     comple… 2017-05-17 10:33:49      3
##  4 139     Triage and Assess… r6 - r4 639     comple… 2017-05-18 02:32:38      4
##  5 139     Blood test         r1 - r6 1068    start   2017-05-18 23:10:39      5
##  6 139     Blood test         r1 - r6 1068    comple… 2017-05-19 03:57:40      6
##  7 139     MRI SCAN           r2      1305    start   2017-05-19 07:57:18      7
##  8 139     MRI SCAN           r2      1305    comple… 2017-05-19 11:34:01      8
##  9 139     Discuss Results    r3 - r7 1873    start   2017-05-19 17:20:52      9
## 10 139     Discuss Results    r3 - r7 1873    comple… 2017-05-19 20:41:58     10
## 11 139     Check-out          r4 - r3 2368    start   2017-05-21 17:29:34     11
## 12 139     Check-out          r4 - r3 2368    comple… 2017-05-21 18:44:55     12
## # … with abbreviated variable names ¹​employee, ²​handling_id, ³​registration_type

1. Currently both eventlog and activitylog are supported by the packages bupaR, edeaR and processmapR. The daqapo package only supports activitylog, while all other packages only support eventlog. While the goal is to extend support for both to all packages, you can in the meanwhile always convert the format of your log using the functions to_eventlog() and to_activitylog().↩︎