If my data does not have a Time parameter, can I create one?
There are flow cytometry platforms that do not export Time as a parameter for their data.
In FCS Express, you can create a Time parameter for data files that do not have a Time parameter that was exported with the file.
To do this, we will use 3 features:
To summarize, Parameter Math will allow us to create new parameters for our data by using existing features of the data. In this example, we will:
- use a keyword token to extract the total number of events within the file,
- create a custom token to help us determine the amount of time it took to acquire the data, by using the keywords $BTIM and $ETIM in a function, MinutesBetween, that extracts the amount of minutes between each time point.
Please note that if your data lacks a Time parameter, the data file will lack the information to provide FCS Express with the arrival times for each event. As a result, FCS Express will equally space each event between the begin time and the end time information stored within the data file.
|1. To get started, open a new blank layout by going to File > New > New.|
|2. Insert a plot that contains your Time-less data file.|
|3. From the View tab, open the Custom Tokens window.|
|4. Add a new Custom Token by clicking on the + sign in the Custom Tokens toolbar.|
|5. Rename the custom token Minutes Between.|
|6. For the custom token formula, add an = sign, then right click to select the Insert Function menu.|
|7. From the Date-Time category, select the function MinutesBetween(start time, end time).
*If you would like to view Time in a unit other than Minutes, you can use other Date-Time Functions, such as HoursBetween, SecondsBetween or MillisecondsBetween.
|8. Within the function, we will need to replace start time and end time with the actual time points coming from our data. We can use the keywords $BTIM and $ETIM for this.|
|9. Clear out the information between the parenthesis and then right click within the parenthesis to select Insert Token.|
|10. Select Keyword from the Insert a Token window and then click Insert.|
|11. In the Create Keyword window, select the Keyword category and then either type the keyword $BTIM in the field or click on the ellipsis to browse for the keyword within the data file., then click OK.|
|12. Add a comma after the keyword that we just added and insert another keyword token, this time for the keyword $ETIM. Close the parenthesis at the end of the function.|
|13. At this point, your function should now look like this.|
|14. Close the Custom Tokens window.|
|15. From the Tools tab, open the Transformations window.|
|16. Within the Transformations window toolbar, click on the triangle next to the + sign.|
|17. Select Parameter Math and rename the transformation Calculated Time.|
|18. Under the Transformation Options section, click New.|
|19. Within the Create New Sequence Item window, enter Calculated Time for the Output Parameter Name.|
|20. Select the Formula option.|
|21. Within the Formula field, enter (row-1)*(.|
|22. After the open parenthesis, right click and select Insert Token.|
|23. From Custom, select the Minutes Between custom token that we created in Step 5.|
|24. After the token, add a /, then right click and select Insert Token.|
|25. Select Keyword, then in the Keyword category, type in $TOT for the keyword to use, then click OK. This is the keyword for the total number of events within the data file.|
|26. After the $TOT keyword, add a ) to close the formula and then click OK.|
|27. At this point, you should see something similar to this:|
|28. To apply the Parameter Math to your data, drag the transformation onto a plot.|
|29. The title of your plot should now reflect that Parameter Math has been applied. The new parameter can now be selected from the X or Y axis.|