Find, Graph, and Download Data

Quick Start

This is the short version of how to select, chart, and download data.

View Tab

1. Narrow the list of Datastreams.
   • Check desired Stations.
   • Check desired Measurements.
2. Scroll down.
3. Check desired datastreams.

Chart Tab

1. Choose date range.
2. Enter chart title name.
3. Hit Chart X Datastreams button.

Download Tab

Note

Download only works if you are logged in. Datastreams will be the same as the Chart Tab

1. Choose date range.
2. Provide download comment.
3. Hit Create Download button.

How to Explore an Organization’s Data

The Dendra interface was designed while working closely with an interdisciplinary team of researchers with the Eel River Critical Zone Observatory. As a result of their input, there is less emphasis on the mapping component and a greater emphasis on the available measurements at the stations.

The explore interface is divided into three parts:

• Find (View)
• Chart
• Download

Find (View) Data

The View tab provides discoverability of measurements in relation to stations. It also allows you to filter by Unit type, e.g. meters, and Purpose.

Note

Leaving a column unchecked means ALL. Checking one or more items in the column is inclusive of checked and exclusive of unchecked.

1. Narrow the list of datastreams

   Stations: these are the monitoring sites. More information on each can be found under the Stations menu and under Station status. A map of the stations can be found on both Station Status and Overview.

   Measurements: controlled vocabulary of observation types. The list is not exhaustive, it shows only the measurements that exist on at least one of the stations within the organization.

   Purpose has three options:

   • Ready to Use: the data you are looking for.
   • Raw: not in geophysical units or requires further processing before usable.
   • Status Information: not an environmental measurement, this is data on the status of the sensors and dataloggers themselves.

   Behavior

   Each station has the total number of datastreams at that station in parentheses.

   Each measurement has the total number of datastreams in all stations in parentheses.

   If you select a station, these numbers change. If there is no measurement at that station, Dew Point for example, it will grey out. Otherwise the number of datastreams will update to how many that station has.

   If multiple stations are selected, it will be for all of them. The same goes for measurements. By checking back and forth, you can discover what is available.

   Tip

   Checking Ready to Use only will grey out all Status and Raw measurements, simplifying your exploration.

   Now scroll down.

2. Select datastreams.

   Dendra works like a shopping cart. Once you have narrowed your selection you will have a list of datastreams that fit your criteria. They are unchecked. You need to check all datastreams you are interested in graphing. Then hit Chart.

Chart Data

Dendra plots time-series line graphs. It allows you to put out multiple charts, keeping your old chart while you go back to the View tab to reselect a new set of datastreams. Each chart is unit-aware and will plot similar units on the same axis, but not different units. Left and right axes are selectable for each datastream. The default is left.

These features, along with Dendra’s in-chart tools, make it a powerful diagnostic tool and useful for initial evaluation of datasets.

Create a Chart

1. Remove any unwanted datastreams using the blue - button on the right hand side.
2. Choose which axis you wish the units to appear (no action: all will be on the left side).
3. Select date range.

   Note

   Timestamps are always in the station’s local timezone without Daylight Savings Time. Timestamp is stored internally in UTC.
4. Chart Title: Type in whatever you wish.
5. Hit Chart X Datastreams.

Use the Chart

The chart pulls data in live from the database.

Caution

There are no restrictions on the amount of data, so if you do something ambitious, such as 20 years of 30 measurements of an eddy flux tower, it will happily try (and probably crash your browser).

Action	How To
Cancel	You can always select the 3 dots on the top right of the graph and choose Remove, even while the graph is drawing.
Zoom	Click-hold will zoom into the graph. A blue magnifying icon with a blue x will appear at the top right of the graph. Clicking it will revert to full time span.
Hide Legend	Icon of a square with diagnonal line. Hides the datastream names at bottom of chart.
Mouse-hover	Hovering the mouse over a time will bring up values for all datastreams at that timestamp. If you have many datastreams, it can overwhelm the graph. Click the thumbtack pin icon to lock the hover in a corner.
Out-of-Range Data	When an instrument goes bad, it may throw data values so large or small that it is impossible to see the rest of the data. Click the icon of two bars with an up and down arrow between. Select the unit you want to adjust, e.g. voltage. Set the max & min to new values. Hit Apply. The chart will adopt the new Y-axis values and will redraw.

Export the Chart

If you wish to use the chart for any reason, click the three dots on the top right and select Export as. You have options to download a chart image (JPG, PNG), an SVG, or even a CSV download of the actual data.

Download Data

Dendra provides CSV download of datasets. Download only works if you are logged in. The download system is built to mix and match any set of datastreams into a single CSV. It constructs each row line by line, so it is possible to create a download of the entire database without running out of RAM.

How to Download Data

The Download tab assumes you wish to download the same set of datastreams you selected in the View tab and graphed in the Chart tab. If you wish to change them, return to the View tab to alter the selection.

1. Select date range. After charting the datastreams, to spot-check the data on a short date range, you may wish to change the range to a much larger set.

2. Enter a download comment (this is primarily for your own information to distinguish downloads).

3. Hit Create Download. Dendra will then process the request on the backend. Once it is ready, it will show up under the downloads notification center next to your user profile (top right on web page).

4. Click on your download, and the CSV will transfer to your computer or device.

API Access

Dendra provides a full-featured API for pulling data using the unique identifiers of each datastream as well. The Python code pulls directly into Panda’s dataframe and includes UTC as well as local time.