Automate a pipeline to run a program and visualize the results using make

gen_sine_data.c

/*
Generate a file with the values for the sine function and its
derivative

The derivative is computed using first order finite differences.

Author: Nicolas Guarin-Zapata
*/
#include <stdio.h>
#include <math.h>
#define PI 3.14159265358979323846

int main ()
{
    int cont, num_vals;
    float x, x_ini, x_end, dx;
    float fx, fx_new, dfx;
    FILE *f;

    x_ini = 0;
    x_end = 1;
    num_vals = 101;
    dx = (x_end - x_ini)/(num_vals -1);
    x = 0;
    f = fopen("sine_data.txt", "w");
    for (cont = 0; cont < num_vals; cont++)
    {
        fx = sin(2*PI*x);
        fx_new = sin(2*PI*(x + dx));
        dfx = (fx_new - fx)/dx;
        fprintf(f, "%f, %f, %f\n", x, fx, dfx);
        x = x + dx;
    }
    fclose(f);

    return 0;
}

Makefile

sine_plot.png : plot_data.py
	python plot_data.py

plot_data.py: gen_sine_data
	./gen_sine_data

gen_sine_data : gen_sine_data.c
	cc -o gen_sine_data gen_sine_data.c -lm

plot_data.py

"""Plot the data in sine_data.txt"""
from __future__ import division
import numpy as np
import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt

plt.style.use("seaborn-white")
red = "#e41a1c"
blue = "#377eb8"

data = np.loadtxt("sine_data.txt", delimiter=",")
x = data[:, 0]
f = data[:, 1]
df = data[:, 2]

plt.plot(x, f, label=r"$\sin(2 \pi x)$", linewidth=2, color=red)
plt.plot(x, df, label="Approximated derivative", linewidth=2, color=blue)
plt.xlabel(r"$x$")
plt.ylabel(r"$y$")
plt.legend(loc="best")
plt.savefig("sine_plot.png", dpi=300, bbox_inches="tight")

sine_data.txt

0.000000, 0.000000, 6.279052
0.010000, 0.062791, 6.254272
0.020000, 0.125333, 6.204808
0.030000, 0.187381, 6.130857
0.040000, 0.248690, 6.032710
0.050000, 0.309017, 5.910754
0.060000, 0.368125, 5.765474
0.070000, 0.425779, 5.597436
0.080000, 0.481754, 5.407313
0.090000, 0.535827, 5.195844
0.100000, 0.587785, 4.963875
0.110000, 0.637424, 4.712307
0.120000, 0.684547, 4.442155
0.130000, 0.728969, 4.154462
0.140000, 0.770513, 3.850377
0.150000, 0.809017, 3.531098
0.160000, 0.844328, 3.197879
0.170000, 0.876307, 2.852035
0.180000, 0.904827, 2.494943
0.190000, 0.929776, 2.128005
0.200000, 0.951057, 1.752669
0.210000, 0.968583, 1.370406
0.220000, 0.982287, 0.982744
0.230000, 0.992115, 0.591201
0.240000, 0.998027, 0.197327
0.250000, 1.000000, -0.197327
0.260000, 0.998027, -0.591207
0.270000, 0.992115, -0.982744
0.280000, 0.982287, -1.370406
0.290000, 0.968583, -1.752663
0.300000, 0.951057, -2.127999
0.310000, 0.929777, -2.494937
0.320000, 0.904827, -2.852035
0.330000, 0.876307, -3.197873
0.340000, 0.844328, -3.531086
0.350000, 0.809017, -3.850371
0.360000, 0.770514, -4.154456
0.370000, 0.728969, -4.442143
0.380000, 0.684548, -4.712307
0.390000, 0.637424, -4.963863
0.400000, 0.587786, -5.195838
0.410000, 0.535827, -5.407307
0.420000, 0.481754, -5.597431
0.430000, 0.425780, -5.765465
0.440000, 0.368125, -5.910748
0.450000, 0.309018, -6.032704
0.460000, 0.248691, -6.130849
0.470000, 0.187382, -6.204802
0.480000, 0.125334, -6.254265
0.490000, 0.062792, -6.279046
0.500000, 0.000001, -6.279065
0.510000, -0.062789, -6.254266
0.520000, -0.125332, -6.204803
0.530000, -0.187380, -6.130854
0.540000, -0.248689, -6.032707
0.550000, -0.309016, -5.910754
0.560000, -0.368123, -5.765471
0.570000, -0.425778, -5.597440
0.580000, -0.481752, -5.407310
0.590000, -0.535825, -5.195850
0.600000, -0.587784, -4.963875
0.610000, -0.637423, -4.712314
0.620000, -0.684546, -4.442155
0.630000, -0.728967, -4.154468
0.640000, -0.770512, -3.850383
0.650000, -0.809016, -3.531098
0.660000, -0.844327, -3.197885
0.670000, -0.876306, -2.852046
0.680000, -0.904826, -2.494955
0.690000, -0.929776, -2.128017
0.700000, -0.951056, -1.752675
0.710000, -0.968583, -1.370424
0.720000, -0.982287, -0.982755
0.730000, -0.992114, -0.591218
0.740000, -0.998027, -0.197345
0.750000, -1.000000, 0.197309
0.760000, -0.998027, 0.591189
0.770000, -0.992115, 0.982726
0.780000, -0.982288, 1.370388
0.790000, -0.968584, 1.752645
0.800000, -0.951057, 2.127987
0.810000, -0.929778, 2.494919
0.820000, -0.904828, 2.852017
0.830000, -0.876308, 3.197861
0.839999, -0.844330, 3.531069
0.849999, -0.809019, 3.850359
0.859999, -0.770515, 4.154444
0.869999, -0.728971, 4.442132
0.879999, -0.684550, 4.712290
0.889999, -0.637427, 4.963857
0.899999, -0.587788, 5.195827
0.909999, -0.535830, 5.407298
0.919999, -0.481757, 5.597422
0.929999, -0.425783, 5.765459
0.939999, -0.368128, 5.910742
0.949999, -0.309021, 6.032700
0.959999, -0.248694, 6.130846
0.969999, -0.187385, 6.204799
0.979999, -0.125337, 6.254262
0.989999, -0.062795, 6.279046
0.999999, -0.000004, 6.279084

sine_plot.png