I have a raster stack of 15 layers. I want to perform Mann Kendall trend test, its significance and Theil sen slope. How can i do this in R for window operating system. The stack has NA values in some layers.
Dear Sandeep,
please follow following steps........
library(Kendall)
fun_kendall=function(x){ return(unlist(MannKendall(x)))}
kendall_result=calc(stack_name,fun_kendall)
You may have a look at this post on the r-sig-geo mailing list some time ago. Here. you will find also some code.
https://stat.ethz.ch/pipermail/r-sig-geo/2012-August/015812.html
You can simply use, 'calc' function from 'raster' package and 'MannKendall' from 'Kendall' package as following, where 's' is your raster stack.
calc(s,function(x){MannKendall(rev(x))$sl})
some additional resources here:
https://www.researchgate.net/post/How_can_I_use_R_software_to_perform_the_Mann-Kendall_Test_for_trend_analysis_and_abrupt_change
https://www.researchgate.net/post/How_can_I_use_R_software_to_perform_the_Mann-Kendall_Test_for_trend_analysis_and_abrupt_change
There is a Kendall package in R available. Using a raster stack requires to reshape the data to a data frame. Check https://cran.r-project.org/web/packages/Kendall/Kendall.pdf for the example and the structure of the example data and bring them into the same form. should work easily. good luck.
Modified Mann-Kendall Test For Serially Correlated Data Using Hamed and Rao (1998) Variance Correction Approach.
Code Modified Mann-Kendall Test For Serially Correlated Data Usin...
Modified Mann-Kendall Test For Serially Correlated Data Using Yue and Wang (2004) Variance Correction Approach.
Code Modified Mann-Kendall Test For Serially Correlated Data Usin...
Dear Amrit,
Can you share how you have solved the issue of applying Mann-Kendall test to raster gridded data!
Dear Sandeep,
please follow following steps........
library(Kendall)
fun_kendall=function(x){ return(unlist(MannKendall(x)))}
kendall_result=calc(stack_name,fun_kendall)
Spatial Efficiency metric (SPAEF) is proven to be robust when comparing two raster maps. Python and Matlab codes are available at: http://space.geus.dk/tools_products/index.html
Two papers on the metric:
1) https://www.hydrol-earth-syst-sci.net/22/1299/2018/hess-22-1299-2018-assets.html
2) https://www.geosci-model-dev-discuss.net/gmd-2017-238/
Complete code please see the following:
######################################################
#
# Mann-Kendall trend test for time series raster data
# tau: Kendall's tau statistic
# sl: two-sided p-value
# S: Kendall Score
# D: denominator, tau=S/D
# varS: variance of S
#
######################################################
library(raster)
library(Kendall)
myfolder
You may use raster.kendall() from "spatialEco" r- package. i.e.
raster.kendall(x, tau = FALSE, intercept = FALSE, p.value = FALSE, z.value = FALSE, confidence = FALSE, autocorrelation = FALSE, ...)
The function results in a raster layer with:
- raster layer 1 Theil-Sen slope
- raster layer 2 Kendall's tau
- raster layer 3 intercept for trend
- raster layer 4 p value for trend
- raster layer 5 Z value
- raster layer 6 lower confidence level at 95-pct
- raster layer 7 upper confidence level at 95-pct
for more details, see www.rdocumentation.org/packages/spatialEco
@ Amrit Thapa;
someone could help if you shared part of your data and code producing the errors.
Anyone can guide me how to remove green background from a Mann Kendall Trend calculated by above give cod
Sandeep Kumar Patakamuri and Lihui Luo it's my sample data and cod. problem is when in ArcMap I set background value as 1 which is the value of this green background, it disappears but the legend still shows a maximum value of 1 which is the background value. How to change it in legend?
@ Sandeep Kumar Patakamuri See the high value in the map is 1(red colour) which does not appear in the map, please guide me on how to solve it.
Geoffrey Ogutu Excuse me!I have executed the function : raster.kendall(x, tau = TRUE, intercept = TRUE, p.value = TRUE, z.value = TRUE, confidence = TRUE) and I just got six layers but not 7 layers just like you have said. why i can't get the Z-value? In addition, although i have read the explanation about the raster.kendall function, i still don't know how to distinguish which layer these parameters correspond to? I hope you can give me some help, thank you !
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