r - calculate average correlation for neighboring pixels through time -

-

i have stack of 4 rasters. average correlation through time between pixel , each of 8 neighbors.

some data:

library(raster)    r1=raster(matrix(runif(25),nrow=5)) r2=raster(matrix(runif(25),nrow=5)) r3=raster(matrix(runif(25),nrow=5)) r4=raster(matrix(runif(25),nrow=5)) s=stack(r1,r2,r3,r4)

so pixel @ position x, has 8 neighbors @ ne, e, se, s etc positions, want average of

cor(x,ne) cor(x,e) cor(x,se) cor(x,s) cor(x,sw) cor(x,w) cor(x,nw) cor(x,n)

and average value saved @ position x in resulting raster. edge cells na or, if possible flag calculate average correlation cells touches (either 3 or 5 cells). thanks!

i don't believe @pascal's suggestion of using focal() work because focal() takes single raster layer argument, not stack. solution easiest understand. made more efficient minimizing number of times extract values each focal cell:

library(raster)    set.seed(2002) r1 <- raster(matrix(runif(25),nrow=5)) r2 <- raster(matrix(runif(25),nrow=5)) r3 <- raster(matrix(runif(25),nrow=5)) r4 <- raster(matrix(runif(25),nrow=5)) s <- stack(r1,r2,r3,r4)  ##  calculate adjacent raster cells each focal cell: <- adjacent(s, 1:ncell(s), directions=8, sorted=t)  ##  create column store correlations: out <- data.frame(a) out$cors <- na  ##  loop on focal cells , adjacencies, ##    extract values across layers , calculate ##    correlation, storing in appropriate row of ##    our output data.frame: (i in 1:nrow(a)) {     out$cors[i] <- cor(c(s[a[i,1]]), c(s[a[i,2]])) }  ##  take mean of correlations focal cell id: r_out_vals <- aggregate(out$cors, by=list(out$from), fun=mean)  ##  create new raster object store our mean correlations in ##    focal cell locations: r_out <- s[[1]] r_out[] <- r_out_vals$x  plot(r_out)

Comments

Post a Comment

Popular posts from this blog

python - How to create jsonb index using GIN on SQLAlchemy? -

-
here's current code creating index jsonb. index("mytable_data_idx_id_key", mytable.data['id'].astext, postgresql_using='gin') but got error. sqlalchemy.exc.programmingerror: (psycopg2.programmingerror) data type text has no default operator class access method "gin" hint: must specify operator class index or define default operator class data type. [sql: "create index event_data_idx_id_key on event using gin ((data ->> 'id'))"] is there way create index on sqlalchemy? the postgresql specific sqlalchemy docs @ http://docs.sqlalchemy.org/en/latest/dialects/postgresql.html#operator-classes mention postgresql_ops dictionary provide "operator class" used postgresql, , provide example illustrating use: index('my_index', my_table.c.id, my_table.c.data, postgresql_ops={ 'data': 'text_pattern_ops', ...
Read more

PHP DOM loadHTML() method unusual warning -

-
i had following code works fine on localhost: $document = new domdocument(); $document->loadhtml($p_result); $form = $document->getelementsbytagname('form')->item(0); // code continues using $form variable after same code updated on outside server, loadhtml() failed , issued warning. warning: domdocument::loadhtml() expects parameter 1 valid path, string given in path/name/to/script.php returned null instead of object code pretty gets fatal error. note contents of $p_result absolutely same on outside server , on localhost. but why displays kind of warning , why not work? doesn't loadhtml() expects argument 1 string in first place? why method expects parameter 1 valid path ? just make clear i'm not calling loadhtmlfile() , i'm calling loadhtml() . thanks. you're affected one of php bugs . issue present in php 5.6.8 , 5.6.9. have affected php version on server, , bug-free version on localhost. the bug forbids null ...
Read more

c# - TransactionScope not rolling back although no complete() is called -

-
i'm using transactionscope rollback transaction fail bool errorreported = false; action<importerrorlog> newerrorcallback = e => { errorreported = true; errorcallback(e); }; using (var transaction = new transactionscope()) { foreach (importtaskdefinition task in taskdefinition) { loader.load(streamfile, newerrorcallback, task.destinationtable, processingtaskid); } if (!errorreported) transaction.complete(); } i'm sure there no transactionscope started ahead or after code. i'm using entity framework insert in db. regardless state of errorreported transaction never rolled in case of error. what missing ? transactionscope sets transaction.current . that's does. wants transacted must @ property. i believe ef each time connection opened reason. probably, connection open when scope installed. open connection inside of scope or enlist manually. ef has nasty "design decision": default opens ...
Read more