我有一个文件,其中包含来自流体模拟的速度大小数据和涡量大小数据。
我想知道这两个数据集的频率是多少。
我的代码:
# -*- coding: utf-8 -*-
"""
Spyder Editor
This is a temporary script file.
"""
import re
import math
import matplotlib.pyplot as plt
import numpy as np
probeU1 = []
probeV1 = []
# this creates an array containig all the timesteps, cutting of the first 180, because the system has to stabelize.
number = [ round(x * 0.1, 1) for x in range(180, 301)]
# this function loops over the different time directories, and reads the velocity file.
for i in range(len(number)):
filenamepath = "/Refinement/Vorticity4/probes/" +str(number[i]) + "/U"
data= open(filenamepath,"r")
temparray = []
#removes all the formatting around the data
for line in data:
if line.startswith('#'):
continue
else:
line = re.sub('[()]', "", line)
values = line.split()
#print values[1], values[2]
xco = values[1::3]
yco = values[2::3]
#here it extracts all the velocity data from all the different probes
for i in range(len(xco)):
floatx = float(xco[i])
floaty = float(yco[i])
temp1 = math.pow(floatx,2)
temp2 = math.pow(floaty,2)
#print temp2, temp1
temp3 = temp1+temp2
temp4 = math.sqrt(temp3)
#takes the magnitude of the velocity
#print temp4
temparray.append(temp4)
probeU1.append(temparray)
#
#print probeU1[0]
#print len(probeU1[0])
#
# this function loops over the different time directories, and reads the vorticity file.
for i in range(len(number)):
filenamepath = "/Refinement/Vorticity4/probes/" +str(number[i]) + "/vorticity"
data= open(filenamepath,"r")
# print data.read()
temparray1 = []
for line in data:
if line.startswith('#'):
continue
else:
line = re.sub('[()]', "", line)
values = line.split()
zco = values[3::3]
#because the 2 dimensionallity the z-component of the vorticity is already the magnitude
for i in range(len(zco)):
abso = float(zco[i])
add = np.abs(abso)
temparray1.append(add)
probeV1.append(temparray1)
#Old code block to display the data and check that it made a wave pattern(which it did)
##Printing all probe data from 180-300 in one graph(unintelligible)
#for i in range(len(probeU1[1])):
# B=[]
# for l in probeU1:
# B.append(l[i])
## print 'B=', B
## print i
# plt.plot(number,B)
#
#
#plt.ylabel('magnitude of velocity')
#plt.show()
#
##Printing all probe data from 180-300 in one graph(unintelligible)
#for i in range(len(probeV1[1])):
# R=[]
# for l in probeV1:
# R.append(l[i])
## print 'R=', R
## print i
# plt.plot(number,R)
#
#
#plt.ylabel('magnitude of vorticity')
#plt.show()
#Here is where the magic happens, (i hope)
ans=[]
for i in range(len(probeU1[1])):
b=[]
#probeU1 is a nested list, because there are 117 different probes, wich all have the data from timestep 180-301
for l in probeU1:
b.append(l[i])
#the freqeuncy was not oscillating around 0, so moved it there by substracting the mean
B=b-np.mean(b)
#here the fft happens
u = np.fft.fft(B)
#This should calculate the frequencies?
freq = np.fft.fftfreq(len(B), d= (number[1] - number[0]))
# If im not mistakes this finds the peak frequency for 1 probe and passes it another list
val = np.argmax(np.abs(u))
ans.append(np.abs(freq[val]))
plt.plot(freq, np.abs(u))
#print np.mean(ans)
plt.xlabel('frequency?')
plt.savefig('velocitiy frequency')
plt.show()
# just duplicate to the one above it
ans1=[]
for i in range(len(probeV1[1])):
c=[]
for l in probeU1:
c.append(l[i])
C=c-np.mean(c)
y = np.fft.fft(C)
freq1 = np.fft.fftfreq(len(C), d= (number[1] - number[0]))
val = np.argmax(np.abs(y))
ans1.append(np.abs(freq1[val]))
plt.plot(freq1, np.abs(y))
#print np.mean(ans1)
plt.ylabel('frequency?')
plt.savefig('vorticity frequency')
plt.show()
data.close()
我的数据包含 117 个探测器,每个探测器都有自己的 121 个速度幅度数据点。
我的目标是找到每个探针的主要频率,然后收集所有这些频率并将它们绘制在直方图中。
我的问题是关于它说这是魔法发生的部分。我相信 fft 已经正常工作了
y = np.fft.fft(C)
freq1 = np.fft.fftfreq(len(C), d= (number[1] - number[0]))
如果我没记错的话,freq1 列表应该包含给定探头的所有频率。我已经目视检查了这个列表,不同频率的数量非常高(20+),所以信号可能非常嘈杂。
# If im not mistakes this finds the peak frequency for 1 probe and passes it another list
val = np.argmax(np.abs(u))
ans.append(np.abs(freq1[val]))
这部分理论上应该从一个探针中获取最大的信号,而不是放在“ans”列表中。但是我对如何无法正确识别正确的频率感到有些困惑。因为理论上应该有一个主频率。如何从所有噪声中的所有这些数据中正确估计“主”频率
作为参考,我正在模拟 Von Karmann 涡街,并且正在寻找涡流脱落的频率。https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_vortex_street
谁能帮我解决这个问题?