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tikzfigure

2D Plots: Functions

pgfplots can evaluate mathematical functions directly, and Python’s math module gives you full flexibility for data generation.

import math
from tikzfigure import TikzFigure

Plotting functions directly

Section titled “Plotting functions directly”

Pass a function expression as a string to func= for smooth curves without pre-computing data points:

fig = TikzFigure()


ax = fig.axis2d(xlabel="x", ylabel="y", xlim=(0, 360), ylim=(-1.5, 1.5), grid=True)


ax.add_plot(func="sin(x)", label=r"$\sin(x)$", color="red", line_width="1.5pt")
ax.add_plot(func="cos(x)", label=r"$\cos(x)$", color="blue", line_width="1.5pt")


ax.set_legend(position="south east")
fig.show()

Show Tikz code 
print(fig)
% --------------------------------------------- %
% Tikzfigure generated by tikzfigure v0.2.1     %
% https://github.com/max-models/tikzfigure      %
% --------------------------------------------- %
\begin{tikzpicture}
    \begin{axis}[xlabel=x, ylabel=y, xmin=0, xmax=360, ymin=-1.5, ymax=1.5, grid=true, legend pos=south east]
        \addplot[color=red, line width=1.5pt] {sin(x)};
        \addplot[color=blue, line width=1.5pt] {cos(x)};
        \legend{$\sin(x)$, $\cos(x)$}
    \end{axis}
\end{tikzpicture}

func accepts any pgfplots expression: sin(x), cos(x), x^2, sqrt(x), exp(x), ln(x), etc.

Comparing functions

Section titled “Comparing functions”

Plot multiple functions side-by-side:

fig = TikzFigure()


ax = fig.axis2d(xlabel="$x$", ylabel="$y$", xlim=(0, 10), ylim=(0, 5), grid=True)


ax.add_plot(func="x", label="$x$", color="black")
ax.add_plot(func="sqrt(x)", label=r"$\sqrt{x}$", color="blue", line_width="2pt")
ax.add_plot(func="x/2", label="$x/2$", color="green")


ax.set_legend(position="north west")
fig.show()

Show Tikz code 
print(fig)
% --------------------------------------------- %
% Tikzfigure generated by tikzfigure v0.2.1     %
% https://github.com/max-models/tikzfigure      %
% --------------------------------------------- %
\begin{tikzpicture}
    \begin{axis}[xlabel=$x$, ylabel=$y$, xmin=0, xmax=10, ymin=0, ymax=5, grid=true, legend pos=north west]
        \addplot[color=black] {x};
        \addplot[color=blue, line width=2pt] {sqrt(x)};
        \addplot[color=green] {x/2};
        \legend{$x$, $\sqrt{x}$, $x/2$}
    \end{axis}
\end{tikzpicture}

Generating data with Python

Section titled “Generating data with Python”

For more complex curves, use Python’s math module with list comprehensions:

fig = TikzFigure()


ax = fig.axis2d(
    xlabel="Angle (radians)",
    ylabel="Amplitude",
    xlim=(0, 6.5),
    ylim=(-1.5, 1.5),
    grid=True,
)


x = [i * 0.1 for i in range(65)]
y_sin = [math.sin(xi) for xi in x]
y_cos = [math.cos(xi) for xi in x]


ax.add_plot(x, y_sin, label=r"$\sin(x)$", color="red")
ax.add_plot(x, y_cos, label=r"$\cos(x)$", color="blue")


ax.set_legend(position="south east")
fig.show()

Show Tikz code 
print(fig)
% --------------------------------------------- %
% Tikzfigure generated by tikzfigure v0.2.1     %
% https://github.com/max-models/tikzfigure      %
% --------------------------------------------- %
\begin{tikzpicture}
    \begin{axis}[xlabel=Angle (radians), ylabel=Amplitude, xmin=0, xmax=6.5, ymin=-1.5, ymax=1.5, grid=true, legend pos=south east]
        \addplot[color=red] coordinates {(0.0,0.0) (0.1,0.09983341664682815) (0.2,0.19866933079506122) (0.30000000000000004,0.2955202066613396) (0.4,0.3894183423086505) (0.5,0.479425538604203) (0.6000000000000001,0.5646424733950355) (0.7000000000000001,0.6442176872376911) (0.8,0.7173560908995228) (0.9,0.7833269096274834) (1.0,0.8414709848078965) (1.1,0.8912073600614354) (1.2000000000000002,0.9320390859672264) (1.3,0.963558185417193) (1.4000000000000001,0.9854497299884603) (1.5,0.9974949866040544) (1.6,0.9995736030415051) (1.7000000000000002,0.9916648104524686) (1.8,0.9738476308781951) (1.9000000000000001,0.9463000876874145) (2.0,0.9092974268256817) (2.1,0.8632093666488737) (2.2,0.8084964038195901) (2.3000000000000003,0.74570521217672) (2.4000000000000004,0.6754631805511506) (2.5,0.5984721441039565) (2.6,0.5155013718214642) (2.7,0.4273798802338298) (2.8000000000000003,0.33498815015590466) (2.9000000000000004,0.23924932921398198) (3.0,0.1411200080598672) (3.1,0.04158066243329049) (3.2,-0.058374143427580086) (3.3000000000000003,-0.15774569414324865) (3.4000000000000004,-0.25554110202683167) (3.5,-0.35078322768961984) (3.6,-0.44252044329485246) (3.7,-0.5298361409084934) (3.8000000000000003,-0.6118578909427193) (3.9000000000000004,-0.6877661591839741) (4.0,-0.7568024953079282) (4.1000000000000005,-0.8182771110644108) (4.2,-0.8715757724135882) (4.3,-0.9161659367494549) (4.4,-0.951602073889516) (4.5,-0.977530117665097) (4.6000000000000005,-0.9936910036334645) (4.7,-0.9999232575641008) (4.800000000000001,-0.9961646088358406) (4.9,-0.9824526126243325) (5.0,-0.9589242746631385) (5.1000000000000005,-0.9258146823277321) (5.2,-0.8834546557201531) (5.300000000000001,-0.8322674422239008) (5.4,-0.7727644875559871) (5.5,-0.7055403255703919) (5.6000000000000005,-0.6312666378723208) (5.7,-0.5506855425976376) (5.800000000000001,-0.4646021794137566) (5.9,-0.373876664830236) (6.0,-0.27941549819892586) (6.1000000000000005,-0.18216250427209502) (6.2,-0.0830894028174964) (6.300000000000001,0.0168139004843506) (6.4,0.11654920485049364)};
        \addplot[color=blue] coordinates {(0.0,1.0) (0.1,0.9950041652780258) (0.2,0.9800665778412416) (0.30000000000000004,0.955336489125606) (0.4,0.9210609940028851) (0.5,0.8775825618903728) (0.6000000000000001,0.8253356149096782) (0.7000000000000001,0.7648421872844884) (0.8,0.6967067093471654) (0.9,0.6216099682706644) (1.0,0.5403023058681398) (1.1,0.4535961214255773) (1.2000000000000002,0.3623577544766734) (1.3,0.26749882862458735) (1.4000000000000001,0.16996714290024081) (1.5,0.0707372016677029) (1.6,-0.029199522301288815) (1.7000000000000002,-0.12884449429552486) (1.8,-0.2272020946930871) (1.9000000000000001,-0.3232895668635036) (2.0,-0.4161468365471424) (2.1,-0.5048461045998576) (2.2,-0.5885011172553458) (2.3000000000000003,-0.6662760212798244) (2.4000000000000004,-0.7373937155412458) (2.5,-0.8011436155469337) (2.6,-0.8568887533689473) (2.7,-0.9040721420170612) (2.8000000000000003,-0.9422223406686583) (2.9000000000000004,-0.9709581651495907) (3.0,-0.9899924966004454) (3.1,-0.9991351502732795) (3.2,-0.9982947757947531) (3.3000000000000003,-0.9874797699088649) (3.4000000000000004,-0.9667981925794609) (3.5,-0.9364566872907963) (3.6,-0.896758416334147) (3.7,-0.848100031710408) (3.8000000000000003,-0.7909677119144165) (3.9000000000000004,-0.7259323042001399) (4.0,-0.6536436208636119) (4.1000000000000005,-0.5748239465332685) (4.2,-0.4902608213406994) (4.3,-0.40079917207997545) (4.4,-0.30733286997841935) (4.5,-0.2107957994307797) (4.6000000000000005,-0.11215252693505398) (4.7,-0.01238866346289056) (4.800000000000001,0.08749898343944727) (4.9,0.18651236942257576) (5.0,0.28366218546322625) (5.1000000000000005,0.37797774271298107) (5.2,0.4685166713003771) (5.300000000000001,0.5543743361791615) (5.4,0.6346928759426347) (5.5,0.70866977429126) (5.6000000000000005,0.7755658785102502) (5.7,0.8347127848391598) (5.800000000000001,0.8855195169413194) (5.9,0.9274784307440359) (6.0,0.960170286650366) (6.1000000000000005,0.9832684384425847) (6.2,0.9965420970232175) (6.300000000000001,0.9998586363834151) (6.4,0.9931849187581926)};
        \legend{$\sin(x)$, $\cos(x)$}
    \end{axis}
\end{tikzpicture}

Exponential growth

Section titled “Exponential growth”

Visualizing exponential functions with Python-generated data:

fig = TikzFigure()


ax = fig.axis2d(
    xlabel="Time (years)", ylabel="Population", xlim=(0, 10), ylim=(0, 1000), grid=True
)


time = [i for i in range(11)]
population = [100 * math.exp(0.1 * t) for t in time]


ax.add_plot(
    time,
    population,
    label="$P(t) = 100 e^{0.1t}$",
    color="darkgreen",
    mark="o",
    mark_size="2pt",
)


ax.set_legend(position="north west")
fig.show()

Show Tikz code 
print(fig)
% --------------------------------------------- %
% Tikzfigure generated by tikzfigure v0.2.1     %
% https://github.com/max-models/tikzfigure      %
% --------------------------------------------- %
\begin{tikzpicture}
    \begin{axis}[xlabel=Time (years), ylabel=Population, xmin=0, xmax=10, ymin=0, ymax=1000, grid=true, legend pos=north west]
        \addplot[color=darkgreen, mark=o, mark size=2pt] coordinates {(0,100.0) (1,110.51709180756477) (2,122.14027581601698) (3,134.9858807576003) (4,149.18246976412703) (5,164.87212707001282) (6,182.21188003905093) (7,201.37527074704767) (8,222.55409284924679) (9,245.960311115695) (10,271.8281828459045)};
        \legend{$P(t) = 100 e^{0.1t}$}
    \end{axis}
\end{tikzpicture}