Reference: EMF User’s Guide
I’ve created a dataset whose description contains the words “webinar homework”. Use the Advanced Dataset search to find it. Refer to Section 3.4.2 Advanced Dataset Search.
I used the same user account to import an external dataset. Find this dataset by filtering the Dataset Manager list by creator.
External datasets don’t store their data in the EMF database. Instead, the EMF keeps track of where the file is on disk. Refer to Section 3.5.7 Sources.
Let’s go back to the first dataset I created, the one whose description includes “webinar homework”. Unlike the external dataset I created, this dataset does have its data stored in the EMF database. This means I can make edits to the data and the EMF will automatically save my revisions.
When I first imported the dataset, the EMF automatically created version 0 of the dataset with the version name “Initial Version”. I’ve created version 1 of the dataset. Refer to Section 3.5.2 Data and Section 3.5.5 Revisions.
I’ve got a question about this dataset so I created a new note that needs an answer from you. In order to create a new note, you’ll need to be editing the properties of this dataset rather than just viewing the properties. If you’re already viewing the properties of the dataset, click the Edit Properties button in the bottom left corner of the Dataset Properiets View window. Otherwise, select the dataset in the Dataset Manager and click the Edit Properties button. In the Notes tab, you should now see an Add button in the bottom left corner. See Figure 3-12.
In your note, be sure to mark it as an answer, set my note as a reference, and set the dataset version matching my question. Also, include your initials in your note summary so I’ll be able to tell your answer apart from everyone else’s. Refer to Section 3.5.4 Notes.
After you fill out your note’s information in the Create New Note dialog (Figure 3-13), click the OK button. Then, be sure to click the Save button at the bottom of the Dataset Properties Editor window to save your note.
Now, let’s try exporting the dataset to a file. When the EMF exports a file, it automatically generates the filename starting from the dataset name as follows:
First, the last modified date of the dataset gets appended to the dataset name in the format “_DDmonYYYY” where DD = two digit day of the month, mon = three character month abbreviation in lower case, and YYYY = four digit year.
After the date, the EMF will append the number of the version you selected to export like “_v1” for version 1. If the dataset version is not final, the version string will be “_nf_v1”.
Next, the EMF checks if the dataset has an EXPORT_PREFIX or EXPORT_SUFFIX defined and prepends or appends the keyword values.
Finally, if you specify a file name prefix in the export dialog, it will be prepended to the filename.
Set up the export described in the above question. Make sure to check the box Download files to local machine?. You don’t need to enter a Purpose when exporting the files to your local machine. Click the Export button to start the export. Refer to Section 3.8 Exporting Datasets.
Check the Status window to see the status of your export. Once you see a message like Completed export of 2011NEIv1_nonpoint_nc_small..., switch to the Downloads window. If you don’t see your file, click the Refresh button. Once the progress bar reaches 100%, right click on the filename and select Open Containing Folder to open the folder where the file was downloaded. Check the name of the file to see if you guessed right.
Use the Row Filter option in the Export dialog to export only the records of the dataset where the pollutant is VOC. Refer to Section 3.8.1 Export Filtering Options.
Tip: the Row Filter option used in the export is also available when viewing the raw data of a dataset. From the Dataset Properties View window, switch to the Data tab. Select the version of the data you want to view, then click the View button. Figure 3-22 shows an example of using the Row Filter in the Data Viewer window. Refer to Section 3.6 Viewing Raw Data.
Examples of the syntax used by the Row Filter are given in Table 3-11. Using the Data Viewer, try out the following examples on the homework dataset:
| Sample Row Filter | Description |
|---|---|
scc = '2102004001' |
Matches rows where the SCC is exactly 2102004001. |
poll like 'PM%' |
Matches rows where the pollutant starts with PM. “%” is a wildcard character. |
scc like '2102004%' or poll = 'NH3' |
Matches rows where the SCC starts with 2102004 or the pollutant is NH3. |
Figure out the syntax to use to only match the rows where the pollutant is VOC. Copy your row filter to the Export dialog. When you export the file, include a file name prefix like voc_only_ so you can distinguish your filtered export file.
poll = 'VOC']Last updated: September 29, 2014