Publications by Ivan Lizarazo
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1. Introduction This notebook illustrates two spatial interpolation techniques: Inverse Distance Weighted (IDW) and Ordinary Kriging (OK). IDW is a deterministic technique. OK is a probabilistic one. Both techniques are used here to get a continuous surface of soil organic carbon (SOC) at 15-30 cm from samples obtained from SoilGrids 250 m. Note th...
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How to download SoilGrids data
1. Introduction This notebook explains how to download SoilGrids raster data using R. The process is illustrated using soil organic carbon stock as variable of interest. Obviously, the code can be replicated using a different variable. Note that I provide a basic explanation of the functions used in the notebook to help beginneers to reproduce & re...
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Geomorphometric terrain attributes
1. Introduction This notebook illustrates how to calculate geomorphometric terrain attributes from gridded digital elevation models. It aims to teach basic geoinformatics concepts & tools to undergraduate agronomy students at Universidad Nacional de Colombia. For calculating terrain attributes, we will use the MultiscaleDTM R package. When creating...
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How to get elevation data?
1. Introduction This notebook illustrates several functionalities to obtain, process and visualize digital elevation models (DEMs) in R. It aims to help Geomatica Basica students at Universidad Nacional de Colombia to get acquainted with DEMs and geomorphometric variables. A few tips for writing your own notebook: Write and run every chunk step-by...
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Charting forest gain and loss
1. Introduction This is an R Markdown notebook which illustrates how to make charts representing Forest gain and loss data obtained from Google Earth Engine (GEE) using the Hansen Global Forest Change v.1.10 (2000-2022) dataset. 2. Setup First of all, it is convenient to clean the R environment: rm(list=ls()) Then, we need to install several libra...
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Making SDG thematic maps
1. Introduction This is an R Markdown notebook which illustrates how to make thematic maps representing Sustainable Development Goals (SDG) Indicators. Our interest here relates to the SDG 6 “Ensure access to water and sanitation for all”. In particular, we want to map the Indicator 6.2.1 which is the “proportion of population using (a) safel...
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Geometric functions for simple features
This notebook illustrates several geometric functions provided by the simple features for R package. More information about this package is available here. 1. Setup library(tmap) library(tmaptools) library(sf) library(readr) library(ggplot2) 2. Data Let’s start reading the toy dataset created using geojson.io functions: list.files() ## [1] "00...
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Again EVA
Introduction This is a very simple notebook which illustrates how to subset EVA 2019-2022 agricultural statistics data provided by UPRA at https://upra.gov.co/es-co/Evas_Documentos/BaseEVA_Agr%C3%ADcola20192022.xlsx. It aims to help Geomatica Basica students at UNAL to gain digital skills in R. Prerequisites It is assumed that you have already dow...
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First steps with the dplyr library
1. Introduction This is an R Markdown Notebook which illustrates main functionalities of the dplyr library. dplyr is a grammar of data manipulation, providing a consistent set of verbs that help you solve the most common data manipulation challenges: mutate() adds new variables that are functions of existing variables select() picks variables base...
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Spatial interpolation of soil organic carbon
1. Introduction This notebook illustrates two spatial interpolation techniques: Inverse Distance Weighted (IDW) and Ordinary Kriging (OK). IDW is a deterministic technique. OK is a probabilistic one. Both techniques are used here to get a continous surface of SOC at 15-30 cm from samples obtained from SoilGrids 250 m. 2. Setup First, clean the mem...
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