Python (matplotlib/basemap): Segmentation fault (core dumped)

Question

I'm running into problems with a simple Python program for plotting maps with the matplotlib and Basemap. I use example code from the Basemap website:

from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
m = Basemap(width=12000000,height=9000000,projection='lcc',
            resolution=None,lat_1=45.,lat_2=55,lat_0=50,lon_0=-107.)
m.shadedrelief()
plt.show()

The program crashed and I got the following message:

Segmentation fault (core dumped)

Very interesting is that changing the next-to-last line to:

m.etopo()

causes the program to plot a map. I don't know where to find the error. Is it matplotlib? Is it basemap? Is it Python? My system? Can anybody help?

My versions:

Python 2.7.3
matplotlib: 1.3.1
basemap version: 1.0.7
numpy version: 1.6.1
Linux: Ubuntu 12.04 / 64 bit

Thanx a lot!

I am not familiar with the mpl toolkit, but it looks like your map is pretty big. Maybe try a smaller map and see if you can make it through the program as there may be a memory allocation issue, notwithstanding the issue that your are running on a x64 bit system. — Paul
– Paul, Commented Feb 3, 2014 at 15:30
Hello, thanks for your replies. But that's not the problem, because testing a smaller map cause the same problem! Regards, John — mcatis
– mcatis, Commented May 20, 2014 at 18:10

Markus Dutschke · Accepted Answer · 2020-07-27 15:32:51Z

0

Im my case, compiling and executing the imshow-example in the examples folder helped to find the bug.

imshow.cpp

#define _USE_MATH_DEFINES
#include <cmath>
#include <iostream>
#include "../matplotlibcpp.h"

using namespace std;
namespace plt = matplotlibcpp;

int main()
{
    // Prepare data
    int ncols = 500, nrows = 300;
    std::vector<float> z(ncols * nrows);
    for (int j=0; j<nrows; ++j) {
        for (int i=0; i<ncols; ++i) {
            z.at(ncols * j + i) = std::sin(std::hypot(i - ncols/2, j - nrows/2));
        }
    }

    const float* zptr = &(z[0]);
    const int colors = 1;

    plt::title("My matrix");
    plt::imshow(zptr, nrows, ncols, colors);

    // Show plots
    plt::save("imshow.png");
    std::cout << "Result saved to 'imshow.png'.\n";
}

In my case, I tried to plot some unallocated memory region.

answered Jul 27, 2020 at 15:32

Markus Dutschke

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