stickplot

In [5]:

    

#!/usr/bin/env python

"""
some code to do a stick plot with MPL

This version uses matplotlib's quiver.

"""

import matplotlib as mpl
import matplotlib.pyplot as plt
import numpy as np

import datetime


    

In [6]:

    

def stick(axes, times, speeds, directions, units=''):
    """
    Create a stick plot of the given data on the given axes.
   
    Stick plots are commonlyu used to display time series of
    a vector quantity at a point, such as wind or ocean current observations.
    
    Call signature::
        stick(axes, times, speed, direction, units='m/s')
   
    Arguments: 
       *axes*:  The axes object you want to plot on
       *times*: An array of datetime objects giving the time of the
                observations
       *speeds*: An array of the velocities of the observations
       *directions*: An array of the directions of the observations (in
                     degrees from North, where North is up on the plot)
       *units*:  A string with the units of the observation
    
    """

    props = {'units' : "dots",
             'width' : 2,
             'headwidth': 0,
             'headlength': 0,
             'headaxislength': 0,
             'scale' : 0.5,
             }

    ##fixme: this should use some smarts to fit the data...
    label_scale = 10
    unit_label = "%3g %s"%(label_scale, units)

    y = np.zeros_like(speeds)
    dir_rad = directions / 180. * np.pi
    u = np.sin(dir_rad) * speeds
    v = np.cos(dir_rad) * speeds

    Q = ax.quiver(times, y, u, v, **props)
    ax.quiverkey(Q, X=0.1, Y=0.95, U=label_scale, label=unit_label, coordinates='axes', labelpos='S')
    yaxis = ax.yaxis
    yaxis.set_ticklabels([])


    

In [8]:

    

## some sample data:

data = np.array([(10,  0.5),
                 (10,  22.5),
                 (10, 45.0),
                 (10, 67.5),
                 (10, 90.0),
                 (10, 112.5),
                 (10, 135.0),
                 (10, 157.5),
                 (10, 180.0),
                 (10, 202.5),
                 (10, 225.0),
                 (10, 247.5),
                 (10, 270.0),
                 (10, 292.5),
                 (10, 315.0),
                 (10, 337.5),
                 ( 8, 157.5),
                 (12, 180.0),
                 (15, 202.5),
                 ( 7, 225.0),
                 ( 5, 247.5),
                 (16, 270.0),
                 (20, 292.5),
                 (22, 315.0),
                 (15, 337.5),
                 (12,  22.5),
                 (17, 25.0),
                 (18, 30),
                 ], dtype=np.float)
data = np.r_[data, data, data, data, data, data]
speeds  = data[:,0]
directions  = data[:,1]
times = range(len(speeds))
#times = [datetime.datetime(2009, 5, 13, 0) + datetime.timedelta(hours=h) for h in times]

fig = plt.figure(1)
fig.clear()

ax = fig.add_subplot(1,1,1)
stick(ax, times, speeds, directions, units='knots')

plt.draw()
plt.show()


    

In [9]:

    

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.dates import date2num
from datetime import datetime, timedelta

def stick_plot(time, u, v, figsize=(16, 6)):
    """Stephane Raynaud: https://www.mail-archive.com/matplotlib-users@lists.sourceforge.net/msg18051.html."""
    fig, ax = plt.subplots(figsize=figsize)
    q = ax.quiver(date2num(time), [[0]*len(x)], u, v, width=0.002,
                  headlength=0, headwidth=0, headaxislength=0)
    ax.axes.get_yaxis().set_visible(False)
    ax.xaxis_date()
    return fig, ax, q

x = np.arange(100, 110, 0.1)
start = datetime.now()
time = [start + timedelta(days=n) for n in range(len(x))]
u = np.sin(x)
v = np.cos(x)

fig, ax, q = stick_plot(time, u, v, figsize=(12, 3))
qk = ax.quiverkey(q, 0.25, 0.75, 0.5, "0.5 N m$^{-2}$", labelpos='N',
                  coordinates='axes' )

fig.savefig('quiver.png')


    

In [11]:

    

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.dates import date2num
from datetime import datetime, timedelta

def stick_plot(time, u, v, figsize=(10, 10)):
    """Stephane Raynaud: https://www.mail-archive.com/matplotlib-users@lists.sourceforge.net/msg18051.html."""
    fig, ax = plt.subplots(figsize=figsize)
    q = ax.quiver(date2num(time), [[0]*len(x)], u, v, width=0.002,
                  headlength=0, headwidth=0, headaxislength=0)
    ax.axes.get_yaxis().set_visible(False)
    ax.xaxis_date()
    return fig, ax, q

x = np.arange(100, 110, 0.1)
start = datetime.now()
time = [start + timedelta(days=n) for n in range(len(x))]
u = np.sin(x)
v = np.cos(x)

fig, ax, q = stick_plot(time, u, v, figsize=(12, 3))
qk = ax.quiverkey(q, 0.25, 0.75, 0.5, "0.5 N m$^{-2}$", labelpos='N',
                  coordinates='axes' )

fig.savefig('quiver.png')


    

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