forked from alexlib/pivpy
/
graphics.py
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/
graphics.py
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# -*- coding: utf-8 -*-
"""
Various plots
"""
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.animation import FuncAnimation, FFMpegWriter
import xarray as xr
import os
def quiver(data, arrScale = 25.0, threshold = None, nthArr = 1,
contourLevels = None, colbar = True, logscale = False,
aspectratio='equal', colbar_orient = 'vertical', units = None):
"""
Generates a quiver plot of a 'data' xarray DataArray object (single frame from a dataset)
Inputs:
data - xarray DataArray of the type defined in pivpy, one of the frames in the Dataset
selected by default using .isel(t=0)
threshold - values above the threshold will be set equal to threshold
arrScale - use to change arrow scales
nthArr - use to plot only every nth arrow from the array
contourLevels - use to specify the maximum value (abs) of contour plots
colbar - True/False wether to generate a colorbar or not
logscale - if true then colorbar is on log scale
aspectratio - set auto or equal for the plot's apearence
colbar_orient - 'horizontal' or 'vertical' orientation of the colorbar (if colbar is True)
Outputs:
none
Usage:
graphics.quiver(data, arrScale = 0.2, threshold = Inf, n)
"""
data = dataset_to_array(data)
x = data.x
y = data.y
u = data.u
v = data.v
if units is not None:
lUnits = units[0] # ['m' 'm' 'mm/s' 'mm/s']
velUnits = units[2]
tUnits = velUnits.split('/')[1] # make it 's' or 'dt'
else:
lUnits, velUnits, tUnits = '', '', ''
if threshold is not None:
data['u'] = xr.where(data['u']>threshold, threshold, data['u'])
data['v'] = xr.where(data['v']>threshold, threshold, data['v'])
S = np.array(np.sqrt(u**2 + v**2))
fig = plt.get_fignums()
if len(fig) == 0: # if no figure is open
fig, ax = plt.subplots() # open a new figure
else:
ax = plt.gca()
if contourLevels is None:
levels = np.linspace(0, np.max(S.flatten()), 30) # default contour levels up to max of S
else:
levels = np.linspace(0, contourLevels, 30)
if logscale:
c = ax.contourf(x,y,S,alpha=0.8,
cmap = plt.get_cmap("Blues"),
levels = levels, norm = plt.colors.LogNorm())
else:
c = ax.contourf(x,y,S,alpha=0.8,
cmap = plt.get_cmap("Blues"),
levels=levels)
if colbar:
cbar = plt.colorbar(c, orientation=colbar_orient)
cbar.set_label(r'$\left| \, V \, \right|$ ['+ lUnits +' $\cdot$ '+ tUnits +'$^{-1}$]')
ax.quiver(x[::nthArr],y[::nthArr],
u[::nthArr,::nthArr],v[::nthArr,::nthArr],units='width',
scale = np.max(S*arrScale),headwidth=2)
ax.set_xlabel('x (' + lUnits + ')')
ax.set_ylabel('y (' + lUnits + ')')
ax.set_aspect(aspectratio)
return fig,ax
def histogram(data, normed = False):
"""
this function will plot a normalized histogram of
the velocity data.
Input:
data : xarray DataSet with ['u','v'] attrs['units']
normed : (optional) default is False to present normalized
histogram
"""
u = np.asarray(data.u).flatten()
v = np.asarray(data.v).flatten()
units = data.attrs['units']
f,ax = plt.subplots(2)
ax[0].hist(u,bins=np.int(np.sqrt(len(u))*0.5),density=normed)
ax[0].set_xlabel('u ['+units[2]+']')
ax[1] = plt.subplot2grid((2,1),(1,0))
ax[1].hist(v,bins=np.int(np.sqrt(len(v)*0.5)),density=normed)
ax[1].set_xlabel('v ['+units[2]+']')
plt.tight_layout()
return f, ax
def contour_plot(data, threshold = None, contourLevels = None,
colbar = True, logscale = False, aspectration='equal', units=None):
""" contourf ajusted for the xarray PIV dataset, creates a
contour map for the data['w'] property.
Input:
data : xarray PIV DataArray, converted automatically using .isel(t=0)
threshold : a threshold value, default is None (no data clipping)
contourLevels : number of contour levels, default is None
colbar : boolean (default is True) show/hide colorbar
logscale : boolean (True is default) create in linear/log scale
aspectration : string, 'equal' is the default
"""
data = dataset_to_array(data)
if units is not None:
lUnits = units[0] # ['m' 'm' 'mm/s' 'mm/s']
# velUnits = units[2]
# tUnits = velUnits.split('/')[1] # make it 's' or 'dt'
else:
# lUnits, velUnits = '', ''
lUnits = ''
f,ax = plt.subplots()
if threshold is not None:
data['w'] = xr.where(data['w']>threshold, threshold, data['w'])
m = np.amax(abs(data['w']))
if contourLevels == None:
levels = np.linspace(-m, m, 30)
else:
levels = np.linspace(-contourLevels, contourLevels, 30)
if logscale:
c = ax.contourf(data.x,data.y,np.abs(data['w']), levels=levels,
cmap = plt.get_cmap('RdYlBu'), norm=plt.colors.LogNorm())
else:
c = ax.contourf(data.x,data.y,data['w'], levels=levels,
cmap = plt.get_cmap('RdYlBu'))
plt.xlabel('x [' + lUnits + ']')
plt.ylabel('y [' + lUnits + ']')
if colbar:
cbar = plt.colorbar(c)
cbar.set_label(r'$\omega$ [s$^{-1}$]')
ax.set_aspect(aspectration)
return f,ax
def showf(data, variables=None, units=None, fig=None):
"""
showf(data, var, units)
Arguments:
data : xarray.DataSet that contains dimensions of t,x,y
and variables u,v and maybe w (scalar)
"""
if variables is None:
xlabel = ' '
ylabel = ' '
else:
xlabel = variables[0]
ylabel = variables[1]
if units is not None:
xlabel += ' ' + units[0]
ylabel += ' ' + units[1]
fig = plt.figure(None if fig is None else fig.number)
for t in data['t']:
d = data.isel(t=t)
plt.quiver(d['x'],d['y'],d['u'],d['v'],d['u']**2 + d['v']**2)
plt.xlabel(xlabel)
plt.ylabel(ylabel)
plt.draw()
plt.pause(0.1)
plt.show()
def showscal(data, property='ken'):
"""
showf(data, var, units)
Arguments:
data : xarray.DataSet that contains dimensions of t,x,y
and a variable w (scalar)
"""
# fig = plt.figure(None if fig is None else fig.number)
# import pdb; pdb.set_trace()
# xlabel = (None if var is None else var[0]) + ' [' + (None if units is None else units[0])+']'
# ylabel = (None if var is None else var[1]) + ' [' + (None if units is None else units[1])+']'
data = data.piv.vec2scal(property=property)
contour_plot(data)
def animate(data, arrowscale=1, savepath=None):
""" animates the quiver plot for the dataset (multiple frames)
Input:
data : xarray PIV type of DataSet
arrowscale : [optional] integer, default is 1
savepath : [optional] path to save the MP4 animation, default is None
Output:
if savepath is None, then only an image display of the animation
if savepath is an existing path, a file named im.mp4 is saved
"""
X, Y = data.x, data.y
U, V = data.u[:,:,0], data.v[:,:,0] # first frame
fig, ax = plt.subplots(1,1)
M = np.sqrt(U**2 + V**2)
Q = ax.quiver(X[::3,::3], Y[::3,::3],
U[::3,::3], V[::3,::3], M[::3,::3],
units='inches', scale=arrowscale)
cb = plt.colorbar(Q)
units = data.attrs['units']
cb.ax.set_ylabel('velocity (' + units[2] + ')')
text = ax.text(0.2,1.05, '1/'+str(len(data.t)), ha='center', va='center',
transform=ax.transAxes)
def update_quiver(num,Q,data,text):
U,V = data.u[:,:,num],data.v[:,:,num]
M = np.sqrt(U[::3,::3]**2 + V[::3,::3]**2)
Q.set_UVC(U,V,M)
text.set_text(str(num+1)+'/'+str(len(data.t)))
return Q
anim = FuncAnimation(fig, update_quiver, fargs=(Q,data,text),
frames = len(data.t), blit=False)
mywriter = FFMpegWriter()
if savepath:
p = os.getcwd()
os.chdir(savepath)
anim.save('im.mp4', writer=mywriter)
os.chdir(p)
else: anim.save('im.mp4', writer=mywriter)
def dataset_to_array(data,N=0):
""" converts xarray Dataset to array """
if 't' in data.dims:
print('Warning: function for a single frame, using first frame, supply data.isel(t=N)')
data = data.isel(t=N)
return data