How to use the Map Graph

[PurpleAir]

The PurpleAir Map supports a graph feature that can be used to easily view data from sensors. This is useful when looking to understand the recent history of a device and its air quality readings.

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Opening The Graph

The PurpleAir map can be used to see recent historical data displayed in a line graph. When on the map, clicking or tapping on a sensor’s map marker will cause the graph to open. The graph will show data for the currently selected data layer. The length of time displayed on the graph will change depending on the selected averaging period. To close the graph, click or tap on the “x” in the top-right corner of the configuration menu window.

Hovering the mouse over or tapping on a point on the graph will display its value as well as the date and time the entry was collected.

Zooming in on The Graph

Zooming in on a Computer

Zooming in on the graph allows you to see data for a specific time range and restrict the y-axis to new maximum and minimum values. To zoom in, click and drag your mouse on a section of the graph. A colored box will show the area you’ve selected, and releasing your mouse click will zoom in on that area.

When zoomed in, you can pan left or right by clicking and dragging the graph while holding down “shift”.

Zooming in on a Mobile Device

If using a mobile device, you can zoom in by pinching with two fingers on the graph. This is the same way you typically zoom in on any other website.

Undoing Zooming

To undo any zooming you have done, click the “Reset zoom” button beneath the graph. This button only appears after you have zoomed in.

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Viewing Multiple Sensors

The graph is capable of comparing data from multiple sources. With the graph open, you can click on a second sensor to add its readings to the graph view. Any number of sensors can be clicked or tapped to overlap their graphs. To highlight the data of a specific channel, hover the mouse cursor over the channel’s name at the bottom of the graph window. Clicking or tapping on the channel name will toggle its visibility. The dashed gray line viewable on the graph displays the average of the graph data. Below is an example of where to click to toggle this option.

By clicking on channel A underlined in the image above, only channel B will display data. This is helpful when viewing sensors with one channel reporting erroneously high, for example, as then the erroneous data won’t appear on the map.

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Viewing Older Data on The Graph

The amount of data visible on the graph is determined by the selected averaging period. Using a larger averaging period will allow you to see data from a longer timespan.

Selected Average	Visible Data
Real-time	2 days
10-minute	3 days
30-minute	7 days
1-hour	14 days
6-hour	90 days
1-day	1 year
1-week	5 years
1-month	20 years
1-year	100 years

If you want to use a lower average but retrieve older data, you will need to go through our API.

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Fullscreen and Downloading Data

Clicking or tapping on the hamburger menu on the graph window provides download options. Selecting “View in full screen” will cause the graph to fill the space of your screen.

While in full screen, the menu option will switch to “Exit from full screen.” Additionally, you can download an image of the graph as a PNG, JPG, PDF, or SVG. The data that appears in the graph can be downloaded by selecting “Download CSV” or “Download XLS.” More information on downloading is available here: Q: How Do I Download Map Graph Data.

The PurpleAir API can be used to download data as well. Using the API you can obtain data from any number of sensors, download multiple types of data simultaneously, and download data regardless of the reported time or averaging period.

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Learn More

PurpleAir Map Guide
Map Troubleshooting Guide
Which AQI Data Layer to Choose

[jcothran (Jeremy Cothran)]

Thanks for posting this description. Would be great to see a link to this from the map page graph section itself, I don’t think most initial or casual users are going to know to look in the forums for this info. Maybe also a note about the download icon hidden in the bottom left corner of the map.

[Ethan]

Hi @jcothran, this is a great idea. I will input it as a feature request to be looked into.

[CDVTA]

can you tell me what A & B is ? What is the meaning of those two ?

[Ethan]

Hi @CDVTA, PA-II edition sensors contain two laser counters that read the air quality independently. If you select a sensor on the PurpleAir map, you will likely see two lines that appear on the graph. Each of these lines represents a single channel in that sensor. They are named channel A and channel B.

[CDVTA]

Thanks for the details

[listemily (emily)]

Thanks, this is useful! I have some suggestions for the UI, and a question.

Suggestion 1:
It is very non-intuitive that the way to get the drop down menus to show up is to click in the tiny grey space above the plot. Maybe you could have words to click to get it to show up. Also, it would be nice to have words to click to hide it. The intuitive way to hide it would be to click on the ‘x’, but that makes the entire plot go away (but oddly not the drop down menus).

Suggestion 2:
There should be simple instructions somewhere on the page that tells the user: “Click on a sensor to add its data to your plot”. I’ve used this map a dozen times now and have only now figured that out, and not until I read this page did I realize that this is how to have data from multiple sensors.

Suggestion 3:
I’d like a button that would change the horizontal (time) axis on the plot to show the last week, and one for the last month. Currently the only way to change the amount of time displayed (I think) is to change the averaging time. I’d rather just compress the data. And I don’t know offhand how much to change the averaging time to see the last week.

Suggestion 4: the legend for the names of the sensors is in a very very small font. Could there be a way to make them larger?

Question: I thought that before I had found a way to see the average of all the sensors in my neighborhood, but I can’t find that now. Is that possible?

Thanks for all your efforts!
Emily

[listemily (emily)]

Oh, it would also be nice to have a single button to click to add the data from all the sensors within the current map zoom to my plot. Because somehow they sometimes get unselected on their own and it is tedious to add one by one.

[Mengistu (Andualem Ayele)]

what is the value listed underA and B mean

[Mengistu (Andualem Ayele)]

how the average of the following data is 30

Average	AQN1 A	AQN1 B
30.8	64.6335338	62.0530958

what about data for 2021, when downloading

[Josh_PurpleAir (Joshua)]

Many PurpleAir sensors use two laser counters to conduct independent measurements. These are referred to as “Channel A” and “Channel B.” Data can be labeled to indicate which channel it’s from.

Could you provide the sensor index, averaging period, data layer, and time that you obtained the provided data? Did you also obtain this from the map or the API?

[Mengistu (Andualem Ayele)]

Thank You for your swift response. example

AQN2_V2

(Attachment raw-pm25-us-epa-gm.xls is missing)

[Mengistu (Andualem Ayele)]

I want data from all stations in addis from 2016 or the date of establishment to the end of Dec 30/2023( for the time being from establishment to today) , the humidity, temperature, wind speed and monthly and yearly PM2.5 data.

[Josh_PurpleAir (Joshua)]

The dotted average line is an average of all data viewable on the graph. In this case, the average is being affected by the higher readings from 2020.

If you would like to download data for all sensors in Addis, you may want to use our API. To do this, you can follow these steps:

1. You’ll first need to create API keys
2. Then you’ll want to obtain sensor indexes for all the sensors you want data from
3. Finally, you can use the Data Download Tool to download historical data from the API.

Please follow our API Use Guidelines. Additionally, the API is a paid service. However, every user gets some usage for free, and sensor owners can contact us for assistance on obtaining data from their devices.

[Andrew]

@listemily These are some fantastic suggestions, and we appreciate the feedback! I’ll pass these along to the map development team.

As for your question about showing averages for all sensors in your neighborhood, if you change the Averaging period, this will change all sensor markers on the map to match the average you’ve chosen.

[RBlum (Robert Blum)]

Hi there. I dont know what happened but the Y line on the graph now extends to 3k. How do I get it back to a more readable level. Perhaps 500? Thanks

[Kieran (Kieran Berryman)]

Hello,

We have sent you an email to begin troubleshooting this issue.