This tutorial has been developed for OpenRefine version 3.3.
Update: please note that as of March 18, 2020, Open Data Toronto has suspended service and so their service is not available for API calls. Until service resumes, please skip step 3, and during step 5, please chose to Get Data From: This Computer and select the 311.json file in the packaged workshop files. This represents a snapshot of the data that will work with the exercises. Please feel free to email firstname.lastname@example.org if you run into difficulties.
Sometimes you don't have your data in a file. Instead you want to use an API call to pull data from elsewhere. OpenRefine can help you make these calls and parse the data you receive.
The goal of this activity is to create a new project by pulling in 311 call data from the City of Toronto into OpenRefine using an API call and then work with the data. You will construct an API call to download a subset of 311 call data in JSON format, and then use OpenRefine to parse that data and put it into a tabular format. You will then use GREL to further manipulate the data (especially working with date formats) and make some discoveries.
Note: This assumes that you have learned the basics of OpenRefine already through the Survey of Household Spending activity and the Citizen Science activity. This also assumes that you have a basic understanding of APIs and JSON. The 311 JSON dataset can be found in the sample data in case the API call does not work.
In this activity, you are going to:
- We are going to use an API from the City of Toronto to gain access to some data they have on their 311 calls (i.e., city service requests regarding pot holes and graffiti). Go to the open.toronto.ca website and click on the Explore the Catalogue button.
- Search for 311 and click on the item 311 – Open311 API Calls for Service Requests.
This next page describes the dataset. At the bottom is some documentation on how to use the API. Under the Download data section, download and open up the first link to a MS Word document, open311api-get-service-requests-readme.
You should see that it describes how to construct the API call and provides some examples. From making a few calls and looking at the dataset, I have learned that the code for Sidewalk – graffiti is CSROSC-14, so let's use that to get only those service requests. Following the example, our API call would be
- Open up a new tab on your browser and copy this URL into it. You should see a hard to read screen full of data in JSON format. We are going to use OpenRefine to help us make sense of this.
- Let’s create a new project. Start up OpenRefine (if it isn’t running) or click on the OpenRefine logo on the top left to go to the main screen.
- Click on Create Project. Select to get the data from Web Addresses (URLs). Copy in the URL we just created (see above) and click on Next.
- OpenRefine has recognized the data as JSON, but it needs our help to make sense of which curly brackets contain individual records. We need to click on the JSON preview to highlight what a complete record is within the curly brackets. Hover over the curly bracket just below service_requests at the top of the file. That should highlight a few lines of code that pertain to a record. You'll see that the next record contained in curly brackets is for a different location. What you hovered over is an example record, so click on it (i.e., click on the curly bracket just below service_requests).
- You should be brought to a preview screen that shows you all the records in the file, nicely laid out with rows and columns. If it looks readable, then OpenRefine has correctly parsed the JSON file. If you're happy with the results, give your project a name at the top and click on Create Project. As you can see, OpenRefine has helped you process and understand the JSON resulting from the API call.
- Now let's use this data to take a closer look at manipulating dates. The last column in our dataset is called requested_datetime. We can use this column to tell us more about when requests came in for this type of complaint. From the requested_datetime column pull down menu, select Facet->Timeline facet You'll see that OpenRefine doesn't realize that this column represents dates and times. But we can fix this.
From the requested_datetime column pull down menu, select Edit cells->Common transforms->To date Now we should be able to see the time line facets and use the handles to narrow down what rows we display. Give it a try to display requests made between two particular dates.
Once you’re done, close the facet window by clicking on the x.
- This column is hard to read, so let's create a new column with a simplified date displayed. From the requested_datetime column pull down menu, select Edit columns->Add column based on this column. Give your column the name Display Date. Then we can use a GREL expression to take this date and put it in a customized date format, such as m/d/y. For the expression, type value.toString('M/d/y') Remember, the preview window will let you see if your expression is working the way you want it to. Then click on OK.
- Another thing we can do with our requested_datetime field is pull out parts of the date to create facets. For example, let's parse the date to find the most popular month of the year for these types of requests. From the requested_datetime column pull down menu, select Edit columns->Add column based on this column. Give your column the name Month. For the expression, type value.datePart("month"). Then click on OK.
- Let's change it to write out the month names. First right now they are being considered numbers, but we need to change them to text in order to do our transformation. From the Month column pull down menu, select Edit cells->Common transforms->To text.
Then from the Month column pull down menu, select Edit cells->Transform For the expression, type value.toDate(false, 'M').toString('MMMM') This tells it to take the text, consider it the month part of a date, but then write it out with its long name format. The false part is to say that our date doesn’t start with the day first. Click OK.
- Finally, let’s see which is the most popular month. From the Month column pull down menu, select Facet->Text facet. In the facet window, click on Sort by count to sort the facets and see which month comes out on top.
That’s it for our 311 calls dataset!