Questions tagged [spectral]
145 questions
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How can a spectral reaction diffusion solver be written on Shadertoy?
Even with a 20 point Laplacian operator there are still coordinate system artifacts with a circularly symmetric seed.
That is one reason to try a spectral solver.
The main code for the above mentioned simplest Laplacian with a forward Euler solver…
David Jonsson
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How to open/read an ENVI file in R
I'm new at using GIS with R and I'm trying to open an ENVI file containing hyperspectral data following the suggestions from this post R how to read ENVI .hdr-file?, but I don't seem to be able to do so. I tried three different approaches but all of…
Adriana Castillo Castillo
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Scikit Spectral Clustering fails to classify concentric circles
Here is some code to set up the clustering problem:
import numpy as np
import matplotlib.pyplot as plt
# KMeans
# # Class=2
# Center(2.5,2.5), r1 = 2, r2 = 1
X1 = np.zeros(500*4)
X2 = np.zeros(500*4)
r1 = 2; r2 = 1; a = 2.5; b = 2.5 # generate…
Ray Jio
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1 answer
R: Inverse fft() to confirm my manual DFT algorithm inaccurate?
Using R, before assessing some metric of accuracy on my own manual implementation of DFT, I wanted to do a sanity check on how well stats::fft() performs by doing the following:
sig.ts = ts( sin(2*pi*freq1*t) + sin(2*pi*freq2*t) );
sig.rt =…
Christian
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How to read wavelength information from envi file in spectral python libraray?
I am working on hyperspectral imagery which is in envi format. I have successfully read it using spectral python library. Now , I want to get each band (wavelength center). Kindly suggest method for this task.
KHIZER
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AttributeError: 'int' object has no attribute '_forward_pre_hooks'
def define_module(self):
ndf, nef = self.df_dim, self.ef_dim
self.encode_img = nn.Sequential(
nn.Conv2d(3, ndf, 4, 2, 1, bias=False),
nn.LeakyReLU(0.2, inplace=True),
# state size. (ndf) x 32 x 32
…
xiaowang888
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1 answer
Spectral viewcube in Google CoLab
Help. Trying to get a hypercube in a Google CoLab Notebook using Python 3.
hdc is a 3d numpy array: [x,y,channel]
This code fails:
!pip install spectral
from spectral import *
view_cube(hdc_reshaped, bands=[29, 19, 9])
This complains…
lr100
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Error: could not find function "interpolate.fft" (R module spectral IS installed)
My code:
library(spectral)
x <- seq(0,99)
y <- sin(x/6) + 0.5*cos(x/22)
z <- interpolate.fft(y)
RStudio says: Error in interpolate.fft(y) : could not find function "interpolate.fft"
When I try to use it as spectral::interpolate.fft(y), the error is…
Greg
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Iterate through rows in hyperspectral image
I have code that displays a hyperspectral images (cube).
I have to images:
Image 1: hyperspectral image that has N number of rows and N number of columns.
Image 2: hyperspectral image that has only one row, but it has the same number of columns…
Reut
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How to use a color palette created with pyplot.Spectral for scatterplots in a loop?
I have a dataset of points in two dimensions that I want to classify using the K-means technique.
The data:
import numpy as np
x1 = np.array([3,1,1,2,1,6,6,6,5,6,7,8,9,8,9,9,8])
x2 = np.array([5,4,5,6,5,8,6,7,6,7,1,2,1,2,3,2,3])
X =…
Carlos Davila
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Butterworth filtering of EEG data in R
I'm very new at R and EEG signalling so please excuse me if the answer to the question is obvious.
I'm trying to perform a Butterworth filter to an EEG signal to extract the Alpha band. When I executed the filter, the resulting signal looked very…
Ian Quest
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Efficiently converting a list of dictionaries with embedded arrays to DataFrame
I have a list of dictionaries, with spectral data inside the responses field. I also have array of wavelengths for labelling the columns for the spectral data. The list/input looks like this:
data = [ {
'date': '2018-01-01',
'measurement':…
Dave
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How to embed a matplotlib annotation action into a function?
With matplotlib you can have interaction with a plotted image for instance for annotation. You then get after the interaction some data that you usually like to save. I would like to incorporate that all in a function, but I don't know how to do…
JMath
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1 answer
Spectral Test in R
I would like to change my code in a way that 10000 points are placed in a [0,1]^2 plot. I tries changing 256 to 10000 but it generates weird placement. I should change the factors 137 and 187 but not sure how to change it. Anyone knows the logic…
antetokounmpo
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Reversing order of colorbrewer palette while using statebins package
statebins( dataset ,state_col= "state", value_col="value",
brewer_pal = "Spectral",)
I'm using statebins package to plot energy consumption of 50 states of US. Though Spectral palette from colorbrewer look well on the plot:
this is in the…
Sadanand Wachche
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