Trajectory Plot inside of 3D transparent sphere using R -

i want make trajectory plot of df inside of transparent 3d sphere.

i searched stackoverflow couldn't find same question. might helpful interested trajectory of vectors.

the df this

df <- data.frame(mx=runif(100,-0.05,0.05),              my=runif(100,-1,1),              mz=runif(100,-0.5,0.5)) 

i agree frank's answer. if want plot trajectories on sphere supplied picture, should bit more careful, since ordinary interpolation won't give paths on sphere. there different options, easiest project paths onto sphere.

require(rgl)  # construct brownian motion on sphere n <- 100 sigma <- 0.5  df <- array(na, dim = c(n, 3)) df[1, ] <- rnorm(3, sd = sigma) # starting point df[1, ] <- df[1, ] / sqrt(sum(df[1, ]^2)) (i in 2:n) {   df[i, ] <- rnorm(3, sd = sigma) + df[i - 1, ]   df[i, ] <- df[i, ] / sqrt(sum(df[i, ]^2)) }  # linear interpolation of observed trajectories, projected onto sphere times <- seq(1, n, length = 1000)  xx <- approx(1:n, df[, 1], xout = times)$y yy <- approx(1:n, df[, 2], xout = times)$y zz <- approx(1:n, df[, 3], xout = times)$y df_proj <- cbind(xx, yy, zz) df_proj <- df_proj / sqrt(rowsums(df_proj ^2))  # plot plot3d(df_proj, type = 'l', col = heat.colors(1000), lwd = 2, xlab = 'x', ylab = 'y', zlab = 'z') rgl.spheres(0, 0, 0, radius = 0.99, col = 'red', alpha = 0.6, = 'lines') 

you can of course same thing smooth trajectories frank's answer:

# smooth trajectories plot  times <- seq(1, n, length = 1000) xx <- spline(1:n, df[, 1], xout = times)$y yy <- spline(1:n, df[, 2], xout = times)$y zz <- spline(1:n, df[, 3], xout = times)$y  df_smooth <- cbind(xx, yy, zz) df_smooth <- df_smooth / sqrt(rowsums(df_smooth^2))  plot3d(df_smooth, type = 'l', col = heat.colors(1000), lwd = 2, xlab = 'x', ylab = 'y', zlab = 'z') rgl.spheres(0, 0, 0, radius = 0.99, col = 'red', alpha = 0.6, = 'lines')