Matplotlib add minor ticker

 

import matplotlib.pyplot as plt

from matplotlib.ticker import MultipleLocator, FormatStrFormatter

majorLocator = MultipleLocator(20)
majorFormatter = FormatStrFormatter('%d')
minorLocator = MultipleLocator(5)


t = np.arange(0.0, 100.0, 0.1)
s = np.sin(0.1*np.pi*t)*np.exp(-t*0.01)

fig, ax = plt.subplots()
plt.plot(t, s)

ax.xaxis.set_major_locator(majorLocator)
ax.xaxis.set_major_formatter(majorFormatter)

# for the minor ticks, use no labels; default NullFormatter
ax.xaxis.set_minor_locator(minorLocator)

plt.show()

Reference:

https://matplotlib.org/2.0.2/examples/pylab_examples/major_minor_demo1.html

Line styles in matplotlib

 

From: https://matplotlib.org/stable/gallery/lines_bars_and_markers/linestyles.html

using matplotlib in C++

g++  -I/usr/include/python3.5/  -I/home/user/.local/lib/python3.5

/site-packages/numpy/core/include /usr/lib/x86_64-linux-gnu/libpython3.5m.so 

test.cc

// complie in a chromebook linux

#include "matplotlibcpp.h"
#include <vector>

namespace plt = matplotlibcpp;

int main() {
  std::vector<double> y = {1, 3, 2, 4};
  plt::plot(y);
  plt::savefig("minimal.pdf");
  plt::show();
}

Reference: 

https://matplotlib-cpp.readthedocs.io/en/latest/examples.html 

http://hilite.me/

Matplotlib notes

# adjust the tick font size 

ax.tick_params(axis='both', which='minor', labelsize=8)

#set tick to right side

ax.yaxis.tick_right()

# remove space between start and end of the axis

plt.margins(x=0)

ax.margins(x=0)

plt.rcParams['axes.xmargin'] = 0

# remove extra fig for subplot

fig.delaxes(axes[1][2])

axes[1,2].set_axis_off()

axes.flat[-1].set_visible(False)

# better minus symbol

matplotlib.rcParams['axes.unicode_minus'] = False

# fontsize

plt.rcParams['font.size'] = '16'

import matplotlib.pyplot as plt

SMALL_SIZE = 8
MEDIUM_SIZE = 10
BIGGER_SIZE = 12

plt.rc('font', size=SMALL_SIZE)          # controls default text sizes
plt.rc('axes', titlesize=SMALL_SIZE)     # fontsize of the axes title
plt.rc('axes', labelsize=MEDIUM_SIZE)    # fontsize of the x and y labels
plt.rc('xtick', labelsize=SMALL_SIZE)    # fontsize of the tick labels
plt.rc('ytick', labelsize=SMALL_SIZE)    # fontsize of the tick labels
plt.rc('legend', fontsize=SMALL_SIZE)    # legend fontsize
plt.rc('figure', titlesize=BIGGER_SIZE)  # fontsize of the figure title

Reference:

https://stackoverflow.com/questions/42045767/how-can-i-change-the-x-axis-in-matplotlib-so-there-is-no-white-space

https://stackoverflow.com/questions/44980658/remove-the-extra-plot-in-the-matplotlib-subplot/44980867

Matplotlib legend location

 

Reference:

https://matplotlib.org/3.1.1/api/_as_gen/matplotlib.pyplot.legend.html

Interactive with matplotlib figure

The interaction with the figure is very important.

Some keyboard shortcuts are helpful.

e.g.

After zoom the figure, you can press 'r' or 'h' to recover to default size.

'f' can show the figure in fullscreen.

Reference:

https://matplotlib.org/3.1.1/users/navigation_toolbar.html

Tricks on ploting figure with matplotlib

plot error-bar and upper limit

# lower & upper limits of the error
lolims = np.array([0, 0, 1, 0, 1, 0, 0, 0, 1, 0], dtype=bool)
uplims = np.array([0, 1, 0, 0, 0, 1, 0, 0, 0, 1], dtype=bool)

ax.errorbar(x, y + 2.1, xerr=xerr, yerr=yerr,
            xlolims=xlolims, xuplims=xuplims,
            uplims=uplims, lolims=lolims,
            marker='o', markersize=8,
            linestyle='none')

plt.legend(frameon=False)




set ticker in log scale
https://stackoverflow.com/questions/44078409/matplotlib-semi-log-plot-minor-tick-marks-are-gone-when-range-is-large

Reference:
https://matplotlib.org/3.1.0/gallery/statistics/errorbar_limits.html

Solutions to problems when plot with matplotlib

1. can not find 'tkinter' in matplotlib
import matplotlib matplotlib.use('agg')

Plot contour/scatter figure by matplotlib

This is my code.

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

x,y,z = np.loadtxt('GRID007.dat',unpack=True)
#plt.tricontourf(x,y,z,np.linspace(int(min(z)),120,30,endpoint=True))
#plt.colorbar(ticks=range(int(min(z)),130,10))
''' plt.tricontourf(x,y,z,[min(z),37,74,111])
'''
plt.scatter(x,y,c=z,vmax=120)
plt.plot(1.07204,0.762,color='red',linestyle="None",marker='*',label=r'best fit ($\chi^2=100$')
#plt.legend()
#plt.colorbar(ticks=[min(z),111,222,333])
plt.colorbar()
plt.savefig(filename='scatter007.pdf',format='pdf',dpi=300)
plt.show()