Tag Archives: Visualization

Mapping Biodiversity data on smaller than one degree scale

23 Feb

Guest Post by Enjie (Jane) LI

I have been using bdvis package (version 0.2.9) to visualize the iNaturalist records of RAScals project (http://www.inaturalist.org/projects/rascals).

Initially, the mapgrid function in the bdvis version 0.2.9 was written to map the number of records, number of species and completeness in a 1-degree cell grid (~111km x 111km resolution).

I applied this function to the RASCals dataset, see the following code. However, the mapping results are not satisfying. The 1 degree cells are too big to reveal the details in the study areas. Also, the raster grid was on top the basemap, which makes it really hard to associate the mapping results with physical locations.

library(rinat)
library(bdvis)

rascals=get_inat_obs_project("rascals")
conf <- list(Latitude="latitude",
             Longitude="longitude",
             Date_collected="Observed.on",
             Scientific_name="Scientific.name")
rascals <- format_bdvis(rascals, config=conf)
## Get rid of a record with weird location log
rascals <- rascals[!(rascals$Id== 4657868),]
rascals <- getcellid(rascals)
rascals <- gettaxo(rascals)
bdsummary(rascals)

a <- mapgrid(indf = rascals, ptype = "records",
             title = "distribution of RASCals records",
             bbox = NA, legscale = 0, collow = "blue",
             colhigh = "red", mapdatabase = "county",
             region = "CA", customize = NULL)

b <- mapgrid(indf = rascals, ptype = "species",
              title = "distribution of species richness of RASCals records",
              bbox = NA, legscale = 0, collow = "blue",
              colhigh = "red", mapdatabase = "county",
              region = "CA", customize = NULL)

rascals01

rascals02

I contacted developers of the package regarding these two issues. They have been very responsive to resolve them. They quickly added the gridscale argument in the mapgrid function. This new argument allows the users to choose scale (0.1 or 1). The default 1-degree cell grid for mapping.

Here are mapping results from using the gridscale argument. Make sure you have bdvis version 0.2.14 or later.

c <- mapgrid(indf = rascals, ptype = "records",
             title = "distribution of RASCals records",
             bbox = NA, legscale = 0, collow = "blue",
             colhigh = "red", mapdatabase = "county",
             region = "CA", customize = NULL,
             gridscale = 0.1)

d <- mapgrid(indf = rascals, ptype = "species",
             title = "distribution of species richness of RASCals records",
             bbox = NA, legscale = 0, collow = "blue",
             colhigh = "red", mapdatabase = "county",
             region = "CA", customize = NULL,
             gridscale = 0.1)

rascals03

rascals04

We can see that the new map with a finer resolution definitely revealed more information within the range of our study area. One more thing to note is that in this version developers have adjusted the basemap to be on top of the raster layer. This has definitely made the map easier to read and reference back to the physical space.

Good job team! Thanks for developing and perfecting the bdvis package.

References

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Creating figures like the paper ‘Completeness of Digital Accessible Knowledge of Plants of Ghana’ Part 4

13 Dec

This is the fourth part of the of the post where are going to create figure 4 Plot of Inventory Completeness against sample size for grid cells. Part 3 of this series we created chronohorogram for understanding seasonality by year of the data records.

If you have not already done so, please follow steps in Part 1 of the post to set up the data. Since this functionality was recently added to package bdvis, make sure you have v 0.2.9 or higher installed on your system.

The first step to generate this plot will be to compute completeness of the data. Package bdvis provides us with a handy function for that, as long as we want to compute the completeness for a degree grid. This was partially covered in an earlier blog post.

comp = bdcomplete(occ)

This command would return a completeness data matrix called comp and generate a plot of inventory completeness values (c) versus number of spices observed (sobs) in the data set as follows.

comp1

head(comp)
   Cell_id nrec   Sobs  Sest      c
 1 35536   3436   243   276.3514  0.8793151
 2 35537   4315   299   318.7432  0.9380592
 3 35538   518    152   187.4118  0.8110483
 4 35896   17148  320   343.9483  0.9303724
 5 35897   7684   300   338.8402  0.8853732
 6 35898   865    169   216.7325  0.7797632

 

The data returned has cell identification numbers, number of records per cell, number of observed and estimated species and the completeness coefficient (c).

The default cut off number of records per grid cell is 50, but let us set that to 100 so we can filter out some grid cells which are data deficient.

comp = bdcomplete(occ, recs=100)

The graph we want to plot is Inventory Completeness (c) against sample size for grid cells (nrec) and not the one provided by default.

plot(comp$nrec, comp$c, main="Completeness vs number of species",
     xlab="Number of species", ylab="Completeness")

Will produce a graph like this:

comp2

 

The problem with this graph is since there is very high variation in number of records per grid cell, majority of points having less than 5000 records are getting mixed up. So let us use log scale for number of records.

plot(log10(comp$nrec), comp$c, main="Completeness vs number of species",
     xlab="Number of species", ylab="Completeness")

comp3

Now this looks better. Let us change the x axis labels to some sensible values, to make this graph easy to understand. For that we will remove the current x axis labels by using xaxt parameter and then construct and add the tick marks and values associated.

plot(log10(comp$nrec),comp$c,main="Completeness vs number of species",
     xlab="Number of records",ylab="Completeness",xaxt="n")
atx <- axTicks(1)
labels <- sapply(atx,function(i) as.expression(bquote(10^ .(i))))
axis(1,at=atx,labels=labels)

comp4

Not let us add the lines to denote the cut off values of completeness we want to consider i.e. higher than 0.5 as inventory completeness values for cells having number of records greater than 1000.

abline(h = 0.5, v = 3, col = "red", lwd = 2)

comp5

Now we may set the point size and shape to match the figure in paper by using pch and cex parameters. The final plot code will be as follows:

plot(log10(comp$nrec),comp$c,main="Completeness vs number of species",
     xlab="Number of records",ylab="Completeness",xaxt="n",
     pch=22, bg="grey", cex=1.5)
atx <- axTicks(1)
labels <- sapply(atx,function(i) as.expression(bquote(10^ .(i))))
axis(1,at=atx,labels=labels)
abline(h = 0.5, v = 3, col = "red", lwd = 3)

comp6

If you have suggestions on improving the features of package bdvis please post them in issues in Github repository and any questions or comments about this post, please poth them here.

References

Visualize completeness of biodiversity data

10 Jun Completeness Visualization

Package bdvis: Biodiversity data visualizations using R is helpful to understand completeness of biodiversity inventory, extent of geographical, taxonomic and temporal coverage, gaps and biases in data. Package bdvis version 0.2.6 is on CRAN now. This version has several features added since version 0.1.0. I plan to post set of blog entries here to describe some of the key features of the package with some code snippets.

The function bdcomplete computes completeness values for each cell. So after dividing the extent of the dataset in cells (via the getcellid function), this function calculates the Chao2 estimator of species richness. In simple terms, the function estimates looking at the data records in each cell and how many species are represented, how complete that dataset.

The following code snippet shows how the data downloaded from Global Biodiversity Information Facility GBIF Data Portal. The .zip file downloaded using the portal has a file occurrence.txt which contains the data records. Copy that file in the working folder and try the following script.

library(bdvis)

# Download GBIF data from data.gbif,org portal and
# extract occurrence.txt file in Data folder
occurrence &lt;- read.delim( 'occurrence.txt',
                         quote='', stringsAsFactors=FALSE)
# Set configuration variables to format data
conf &lt;- list(Latitude='decimalLatitude',
             Longitude='decimalLongitude',
             Date_collected='eventDate',
             Scientific_name='specificEpithet')
occurrence &lt;- format_bdvis(occurrence, config=conf)
# Compute completeness and visualize using mapgrid
comp=bdcomplete(occurrence)
mapgrid(comp,ptype='complete')

The completeness function produces a graph showing Completeness vs number of Species. More points in higher range of completeness indices indicates better data.

 Completeness vs Species

Completeness vs Species

Now to visualize the data spatially, if any particular region needs better sampling the function mapgrid can now be used with ptype = “complete” parameter. This plots all the grids that have data records more than recs parameter (default = 50) using a color range from light purple to dark blue. Darker the color better the data in that cell.

Completeness Visualization

Completeness Visualization

References: