An overview of the woprVision web application

WorldPop Research Group
University of Southampton

17 November 2020

Introduction

woprVision is an interactive web map that allows you to query population estimates for specific locations and demographic groups from the WorldPop Open Population Repository. This can be used to:

  1. Download the latest population data sets and documentation,
  2. Retrieve population estimates within user-defined geographic areas by clicking the map,
  3. Get estimates of population sizes for specific demographic groups (i.e. age and sex), and
  4. Get probabilistic estimates of uncertainty for all population estimates.
  5. Run the woprVision web application locally from the R console.

This document provides instructions how to use each control panel:

woprVision is part of the wopr package for the R statistical programming language. woprVision was created using the shiny and leaflet packages for R (Chang et al. 2018, Cheng et al. 2018, R Core Team 2019). See the "R package" tab for more information.

Quick Start

On the "Map" tab:
1. Select a data set (i.e. country and version)
2. Click the map to select a location
3. Click "Submit"" to retrieve the population estimate for that location
4. Click "Save" to save the population estimate to the "Saved" tab
5. Click "Draw an Area" and then draw a polygon using the toolbar in the top-left of the map
6. Click "Submit" to retrieve the population estimate for that area
7. Use the sliders to select an age and sex group
8. Click "Submit" to retrieve the population estimate for the selected demographic group in the selected location

Application Components

User Controls

The user control panel is on the left side of the "Map" tab with controls that you can use to retrieve population estimates.

Choose Population Data Select the population data set that you would like to query. This includes a country and version number. You can read more about the selected data set in the "Data Readme" tab.

Select a Location You can select point locations with the "Click the Map" tool. You can draw a polygon to select an area with the "Draw an Area" tool. You can upload a geojson file with points or polygons using the "Upload File" tool.

Submit Button After you have selected a location (using the "Click the Map" or "Draw an Area" selection tools), use the "Submit" button to retrieve population esimates for that location from the WOPR servers.

Save Result Click the "Save" button to save the current result to the "Saved" tab. You can add an optional name in the "Save Result As" input box.

Age-sex Groups Use the sliders to select the age-sex groups that you would like a population estimate for.

Confidence Level The confidence level for the confidence intervals. This defaults to 95%. In that case, there is a 95% chance that the true population in that location is within the confidence interval provided in the results (based on a given statistical model and input data).

Confidence Type The type of confidence interval.

Population Threshold The population threshold provided here will be used to calculate the probability that the population exceeds that threshold. The default value is 100. This will return the probability that the population exceeds 100 people.

Map Window

Basemaps
The following basemaps can be selected from the topright panel in the map window:

Map Layers
The following map layers can be toggled on or off from the top-right panel in the map window:

Draw Toolbar
The draw toolbar appears on the left side of the map window when you select the "Draw an Area" selection tool. The toolbar has three tools:

Zoom
The zoom controls are in the top-left corner of the map window. The plus and minus buttons zoom in and out. The button with the Earth icon resets to the initial zoom level (zoomed out).

Results

The results panel contains two plots that represent the population at the selected location. The top plot shows the probability distribution representing the population estimate and the bottom plot shows a population pyramid representing the age-sex structure.

Population Estimate The population estimate is the mean of the probability distribution shown in the plot. The probability distribution is the predicted posterior probability distribution from a Bayesian statistical model (see "Data Readme" tab for details). The confidence intervals are calculated based on the settings selected in the user controls (see "User Controls: Confidence Level" and "user Controls: Confidence Type"). The probability of exceeding the selected population threshold is also reported in the top plot (see "User Controls: Population Threshold").

Age-sex Structure The estimates of demographic structure that make-up the population pyramids are used here with permission from the WorldPop Global High Resolution Population Denominators project (Pezzulo et al. 2017, WorldPop et al. 2018). These data provide regional estimates of the proportion of the population in each age-sex group across the study area.

Tabs

Map
This is the default tab. It can be used to to toggle between datasets and to retrieve population estimates for specific areas by clicking the map or drawing a polygon. This tab contains a Leaflet map in the middle, a user control panel on the left, and a results panel on the right.

Saved
This tab has a spreadsheet that contains any population estimates that you have saved. The spreadsheet can be saved to your computer as a .csv file by clicking "Download" or it can be deleted by clicking "Clear".

Results include the following columns:

The remaining columns record user inputs that were used to generate the results:

Data Readme
The "Data Readme" tab provides the WorldPop data release statement for the population data set that is currently selected in the "Map" tab. Release statements provide information about the population data set and how it was produced.

WOPR Download
This tab allows you to download the population data directly from the WorldPop Open Population Repository (WOPR). The README files provide descriptions of the datasets that can be reviewed prior to downloading files.

R package
This tab provides a description of the wopr package for the R statistical programming language. The package gives you access to the WorldPop Open Population Repository from your R console allowing you to run woprVision locally, to download data directly from the R console, and to submit spatial queries to the WOPR server to get population estimates for polygons or points from your own shapefiles.

REST API
This tab provides an overview of the WOPR REST API. This is the way that the wopr R package and woprVision communicate with WorldPop servers to retrieve population estimates. The document provides the basic information that you need to develop your own applications that query data from the WorldPop Open Population Repository using REST API.

Contributing

The WorldPop Open Population Repository (WOPR) was developed by the WorldPop Research Group within the Department of Geography and Environmental Science at the University of Southampton. Funding was provided by the Bill & Melinda Gates Foundation and the United Kingdom Foreign, Commonwealth & Development Office (OPP1182408, OPP1182425, INV-002697). Professor Andy Tatem provides oversight of the WorldPop Research Group. The wopr R package was developed by Doug Leasure. Maksym Bondarenko and Niko Ves developed the API backend server. Edith Darin added multi-lingual functionality to the Shiny app and the French translation. Natalia Tejedor Garavito proofread the Spanish translation. Sandra Baptista proofread the Portuguese translation. Gianluca Boo created the WOPR logo. Population data have been contributed to WOPR by many different researchers within the WorldPop Research Group.

Suggested Citation

Leasure DR, Bondarenko M, Darin E, Tatem AJ. 2021. wopr: An R package to query the WorldPop Open Population Repository, version 1.0.0. WorldPop, University of Southampton. doi: 10.5258/SOTON/WP00716. https://github.com/wpgp/wopr

License

GNU General Public License v3.0 (GNU GPLv3)

References

Chang W, Cheng J, Allaire JJ, Xie Y. 2018. shiny: Web Application Framework for R. R package version 1.1.0, https://CRAN.R-project.org/package=shiny.

Cheng J, Karambelkar B, Xie Y. 2018. leaflet: Create Interactive Web Maps with the JavaScript 'Leaflet' Library. R package version 2.0.2. https://CRAN.R-project.org/package=leaflet

Pezzulo C, Hornby GM, Sorichetta A, Gaughan AE, Linard C, Bird TJ, Kerr D, Lloyd CT, Tatem AJ. 2017. Sub-national mapping of population pyramids and dependency ratios in Africa and Asia. Sci. Data 4:170089 https://dx.doi.org/10.1038/sdata.2017.89

R Core Team. 2019. R: A Language and Environment for Statistical Computing, version 3.6.2. R Foundation for Statistical Computing: Vienna, Austria. https://www.R-project.org

WorldPop (www.worldpop.org - School of Geography and Environmental Science, University of Southampton; Department of Geography and Geosciences, University of Louisville; Departement de Geographie, Universite de Namur) and Center for International Earth Science Information Network (CIESIN), Columbia University (2018). Global High Resolution Population Denominators Project - Funded by The Bill & Melinda Gates Foundation (OPP1134076). https://www.worldpop.org/doi/10.5258/SOTON/WP00646