Csound Plot Notebook¶

By Jacob Joaquin
jacobjoaquin@gmail.com
twitter @jacobjoaquin
May 9th, 2013

This is just a collection of graphs that can potentially be in future Csound IPython Notebook based papers. Much of everything I did here I learned from studying matplotlib - 2D and 3D plotting in Python by J.R. Johansson. Though this is a Csound notebook, no actual sound is generated as this notebook focuses solely on graph design.

Boot Up Csound¶

The following cell loads boots the Csound 6 API and defines a few time saving functions.

In [1]:

import csnd6

cs = csnd6.Csound()
csPerf = csnd6.CsoundPerformanceThread(cs)
cs.SetOption('-odac')
cs.CompileOrc('''
sr = 44100
kr = 4410
ksmps = 10
nchnls = 1
0dbfs = 1.0
''')
cs.Start()
csPerf.Play()
def copy_table_data(t):
    
    '''Copy Csound table data into a Python List'''
    
    length = cs.TableLength(t)
    array = csnd6.doubleArray(length)
    cs.TableCopyOut(t, array)
    table = []
    
    for i in xrange(length):
        table.append(array[i])

    return table

def gen_table(*args):
    '''Generate a Csound Table'''
    
    table_index = str(args[0])
    data = ', '.join(map(str, list(args)))
    data = 'gitable_' + str(table_index) + ' ftgen ' + data
    cs.CompileOrc(data)

Amplitude Envelope¶

The graph is based on the following linseg line of code:

In [2]:

fig, ax = subplots(figsize=(8, 4))

ax.vlines(1, 0, 1, 'black', 'dashed')

ax.set_title('linseg Envelope', fontsize=22)

ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)
ax.xaxis.set_ticks_position('bottom')
ax.yaxis.set_ticks_position('left')

ax.set_xticks([0, 1, 2])
ax.set_xticklabels(['0.0', 'idur / 2', 'idur'])
ax.set_xlabel('Time', fontsize=18)
ax.set_xlim([0, 2])

ax.set_yticks([0, 1])
ax.set_yticklabels([0.0, 'iamp'])
ax.set_ylabel('Amplitude', fontsize=18)
ax.set_ylim([0.0, 1.1])

ax.plot([1, 1, 0], lw=4, color='black')

Out[2]:

[<matplotlib.lines.Line2D at 0x42b2050>]

Band-limited Saw Wave¶

Plotting a Csound table.

In [3]:

gen_table(1, 0, 8192, 10, *(map(lambda x: 1.0 / (x + 1), range(16 + 1))))
table_data = copy_table_data(1)
table_length = cs.TableLength(1)
fig, ax = subplots(figsize=(10, 6))
xlim(0, table_length)
ax.hlines(0, 0, table_length)
ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)
ax.spines['bottom'].set_visible(False)
ax.set_xticks(xrange(0, table_length + 1, table_length / 4))
ax.xaxis.set_ticks_position('bottom')
ax.yaxis.set_ticks_position('left')
ax.plot(table_data, color='black', lw=2)

Out[3]:

[<matplotlib.lines.Line2D at 0x2b0b050>]

Grid of Graphs¶

This shows a 4x4 grid of graphs, showcasing the evolution of a band-limited saw wave.

In [4]:

for h in range(1, 17):
    gen_table(h, 0, 128, 10, *(map(lambda x: 1.0 / (x + 1), range(h))))

In [5]:

fig, ax = subplots(4, 4, figsize=(12, 12))

table = 1
for x in xrange(4):
    for y in xrange(4):
        table_length = cs.TableLength(table)
        ax[x][y].hlines(0, 0, table_length)
        ax[x][y].spines['top'].set_visible(False)
        ax[x][y].spines['right'].set_visible(False)
        ax[x][y].spines['bottom'].set_visible(False)
        ax[x][y].xaxis.set_ticks_position('none')
        ax[x][y].yaxis.set_ticks_position('left')
        ax[x][y].plot(copy_table_data(table) + [0], lw=2, color='black')
        ax[x][y].set_xticks([])
        ax[x][y].set_title('harmonics = ' + str(table), fontsize=10)

        table += 1

Discrete Points¶

This example showcases a way to display data from a Csound table as discrete points.

In [6]:

gen_table(1, 0, 32, 10, 1)
sine_table = copy_table_data(1)

In [7]:

table_length = cs.TableLength(1)
fig, ax = subplots(figsize=(12, 6))

ax.hlines(0.0, 0, table_length, 'black')
ax.set_title(str(table_length) + ' Point Sine Wave Table', fontsize=22)

ax.spines['top'].set_visible(False)
ax.spines['bottom'].set_visible(False)
ax.spines['right'].set_visible(False)
ax.xaxis.set_ticks_position('none')
ax.yaxis.set_ticks_position('left')

ax.set_xlabel('Index', fontsize=18)
ax.set_xticks(xrange(table_length))
ax.set_xlim([0, table_length])

ax.set_ylabel('Value', fontsize=18)
ax.set_ylim([-1.1, 1.1])

for i, v in enumerate(sine_table):
    ax.vlines(i, 0.0, v, linewidth=0.5)

ax.plot(sine_table, lw=4, color='black', ls='*', marker='s',
        markersize=9, markeredgewidth=2, markeredgecolor="white")

Out[7]:

[<matplotlib.lines.Line2D at 0x67abcf0>]

Harmonic Strength¶

An example for showing harmonic strength.

In [8]:

n_harmonics = 32
fig, ax = subplots(figsize=(12,8))

ax.set_title('Harmonic Strength', fontsize=22)
ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)
ax.xaxis.set_ticks_position('none')
ax.yaxis.set_ticks_position('left')
ax.set_xticks(xrange(1, n_harmonics + 1))
ax.set_xlim([0, n_harmonics + 1])
ax.set_ylim([0, 1.0])
ax.set_xlabel('Harmonic', fontsize=18)
ax.set_ylabel('Amplitude', fontsize=18)

for i in xrange(1, n_harmonics + 1):
    ax.vlines(i, 0, 1.0 / i, lw=4)

Shutting Down Csound¶

In [9]:

csPerf.Stop()