lcapy.sequence.Sequence

class lcapy.sequence.Sequence(seq, ni=None, origin=None, evaluate=False, var=None, start_trunc=False, end_trunc=False)

Bases: ExprList, SeqDomain

Methods

DTFT([var])	Convert to Fourier domain using discrete time Fourier transform.
__init__(seq[, ni, origin, evaluate, var, ...])	Sequences can be created from an tuple, list, or ndarray.
append(x)	Concatenate with sequence x.
as_array()	Numerically evaluate and store as NumPy array.
as_impulses([var])	Convert to discrete-time signal in the form of a weighted sum of delayed impulses.
convolve(h[, mode])	Convolve with h.
copy()	Return a shallow copy of the list.
delay([m])	Return a new sequence delayed by an integer number of samples m.
discrete_time_fourier_transform([var])	Convert to Fourier domain using discrete time Fourier transform.
evaluate([ni])	Evaluate expression at sequence indices specified by arg.
lfilter([b, a])	Implement digital filter specified by a transfer function.
plot([ni])	Plot the sequence.
pretty(**kwargs)	Make pretty string.
prune()	Remove zeros from ends of sequence.
repeat(x)	Repeat sequence x times.
truncate(size)	Truncate sequence length to size samples.
zeroextend()	Extend sequence by adding zeros so that the origin is included.
zeropad(M)	Add M zeros to end of sequence:

Attributes

expr	Convert sequence to an Lcapy expression.
extent	Determine extent of the sequence.
is_sequence
isempty	True if empty sequence (zero).
origin	Return the element index for n == 0.
quantity
vals	Return the SymPy values as a list.
var

DTFT(var=None, **assumptions)

Convert to Fourier domain using discrete time Fourier transform.

append(x)

Concatenate with sequence x.

as_array()

Numerically evaluate and store as NumPy array.

as_impulses(var=None)

Convert to discrete-time signal in the form of a weighted sum of delayed impulses. For example, {1, 2, 3} -> ui[n] + 2 * ui[n - 1] + 3 * ui[n - 2]

convolve(h, mode='full')

Convolve with h.

copy()

Return a shallow copy of the list.

delay(m=0)

Return a new sequence delayed by an integer number of samples m. If m is negative, the sequence is advanced.

discrete_time_fourier_transform(var=None, **assumptions)

Convert to Fourier domain using discrete time Fourier transform.

evaluate(ni=None)

Evaluate expression at sequence indices specified by arg. arg may be a scalar or a vector. The result is of type float or complex. Zeroes are returned for indices outside the sequence extent.

If arg is iterable, a NumPy array is returned.

property expr

Convert sequence to an Lcapy expression.

property extent

Determine extent of the sequence.

For example, Sequence([1, 1]).extent = 2

Sequence([1, 0, 1]).extent = 3 Sequence([0, 1, 0, 1]).extent = 3

property isempty

True if empty sequence (zero).

lfilter(b=None, a=None)

Implement digital filter specified by a transfer function. The transfer function is described by a vector b of coefficients for the numerator and an a vector of coefficients for the denominator.

If you would like the response with initial conditions see DTfilter.response().

For a FIR filter a = [1].

property origin

Return the element index for n == 0. This may raise a ValueError if the origin is not in the sequence.

plot(ni=None, **kwargs)

Plot the sequence. If ni is not specified, it defaults to the sequence indices. ni can be a vector of specified sequence indices, a tuple specifing the range, or a constant specifying the maximum value with the minimum value set to 0.

kwargs include: axes - the plot axes to use otherwise a new figure is created xlabel - the x-axis label ylabel - the y-axis label xscale - the x-axis scaling, say for plotting as ms yscale - the y-axis scaling, say for plotting mV unfilled - the markers are unfilled markersize - sets the size of the marker markerfacecolor - sets the marker color in addition to those supported by the matplotlib plot command.

The plot axes are returned.

pretty(**kwargs)

Make pretty string.

prune()

Remove zeros from ends of sequence.

{0, 0, 1, 2, 3, 0} -> {1, 2, 3}

repeat(x)

Repeat sequence x times.

seq((1, 2, 3)).repeat(2) gives {1, 2, 3, 1, 2, 3}

truncate(size)

Truncate sequence length to size samples.

property vals

Return the SymPy values as a list.

zeroextend()

Extend sequence by adding zeros so that the origin is included. This is used for printing.

zeropad(M)

Add M zeros to end of sequence:

For example, with M = 3

{1, 2, 3} -> {1, 2, 3, 0, 0, 0}