Create equidistant points along (Poly)line in R -

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if have spatial lines object this:

require(sp)  x <- c(18.25721, 18.25763,18.25808,18.25846,18.25864,18.25886,18.25892,18.25913,18.25940,18.25962,        18.25976,18.25997,18.26021,18.26048,18.26061,18.26086,18.26107,18.26128,18.26154,18.26219,        18.26276,18.26350,18.26445,18.26510,18.26584,18.26668,18.26704,18.26807,18.26850,18.26944,        18.27020,18.27080,18.27111,18.27134,18.27168,18.27191,18.27217,18.27254,18.27309,18.27345,        18.27368,18.27389,18.27398,18.27400,18.27392,18.27383,18.27370)   y <- c(44.69540,44.69539,44.69544,44.69552,44.69563,44.69586,44.69608,44.69644,44.69672,44.69687        ,44.69701,44.69718,44.69737,44.69763,44.69771,44.69778,44.69781,44.69781,44.69782,44.69776        ,44.69772,44.69778,44.69794,44.69805,44.69814,44.69822,44.69824,44.69826,44.69821,44.69805        ,44.69775,44.69737,44.69728,44.69717,44.69701,44.69687,44.69671,44.69649,44.69616,44.69598        ,44.69578,44.69560,44.69539,44.69513,44.69490,44.69476,44.69453)  river<-spatiallines(list(lines(line(cbind(x,y)), id="a"))) proj4string(river) <- crs("+init=epsg:4326")

how possible create points along line every 3m example. result this: enter image description here

i cant figure out or find package that.

don't know of library can achieve result way:

norm_vec <- function(x) sqrt(sum(x^2)) new_point <- function(p0, p1, di) { # finds point in distance di point p0 in direction of point p1     v = p1 - p0     u = v / norm_vec(v)     return (p0 + u * di) }  find <- function(river, m) {    result = river[1,,drop=false]    # subsequent points p1, p2 in data.frame norm_vec(p2 - p1) = m @ times   equidistantpoints = river[1,,drop=false]    river = tail(river, n = -1)   accdist = 0     while (length(river) > 0) {     point = river[1,]     lastpoint = result[1,]      dist = norm_vec(point - lastpoint)          if ( accdist + dist > m ) {       np = new_point(lastpoint, point, m - accdist)       equidistantpoints = rbind(np, equidistantpoints) # add np equidistantpoints       result = rbind(np, result) # add np result       accdist = 0 # reset accdist     } else {       #move point river result         river = tail(river, n = -1)       result = rbind(point, result)           #update accdist         accdist = accdist + dist     }   }   allpoints = result[nrow(result):1,] # reverse result   return(list(newpoints = equidistantpoints, allpoints = allpoints)) }

see plotted:

r = cbind(x,y)  result = f(r, 0.003) plot(result$allpoints, type="l", col="red", asp = 1) points(result$allpoints, col="red") points(result$newpoints, col="cyan")

enter image description here

the basic idea keep moving along river , calculate distance last "checkpoint" when realise accdist + dist > m means between lastpoint , point new point np must created such accdist + dist_to_new_point = m. add point result , moving along river.


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