erro ao exportar dados numpy para csv para pgfplots

Question

Tenho que plotar dados de uma simulação numérica. Eu realizo minhas simulações com pythone numpy. Mas agora quero plotar o resultado em um arquivo LaTeX. Como desejo modificar o layout sem executar novamente a simulação, acho que exportar meus resultados em um csvarquivo e depois ler esse arquivo pgfplotsé uma boa solução. Infelizmente, quando faço isso obtenho resultados diferentes de quando ploto, matplotlibpor exemplo.

Aqui está o que obtenho matplotlib:

E aqui está o que obtenho com pgfplots:

O pgfplotsresultado foi gerado com o seguinte código LaTeX:

\documentclass[12pt]{standalone} 
\usepackage[T1]{fontenc}
\usepackage{tikz}                       % 
\usepackage{pgfplots}                   %
    \pgfplotsset{compat=newest}         %


\begin{document}
\begin{tikzpicture} 
    \begin{axis}[colormap/viridis,
                enlarge y limits=false,
                axis equal image,
                axis on top,
                colorbar,
            ]           

        \addplot[ 
                matrix plot*, point meta=explicit, mesh/cols=10,
            ]
            table[x=y, y=x, 
                meta=T, ignore chars={\#}, col sep=comma,
                ] 
            {hydrostat.csv};

    \end{axis}  
\end{tikzpicture}
\end{document}

E o arquivo hydrostat.csvpode ser obtido através deste link: https://transfernow.net/103fg0a2hl44

Este arquivo foi gerado a partir do comando numpyas (onde está o campo de saída, são as coordenadas e são as dimensões da malha):npT1XYlyly

np.savetxt('./hydrostat.csv', np.column_stack(( np.reshape(X, (lx*ly,1)), np.reshape(Y, (lx*ly,1)), np.reshape(T1, (lx*ly,1))  )), header='x, y, T', comments='# ',delimiter=',', newline='\n' )

Acho que não é grande coisa, apenas uma configuração errada do pgfplots, mas não consigo encontrar.

Parece que falta um número de linhas e colunas, então tentei alterar mesh/colsos valores, mas os resultados foram piores. Eu também tento coisas como exportar em matplotlibformato pgf, mas ele cria uma pngimagem, então não há como mudar para o layout sem executar novamente a simulação. O mesmo está acontecendo com matplotlib2tikz.

Agradecemos antecipadamente por ajudar a encontrar meu erro.

Answer 1

Versão curta

Graças aos comentários de Marmot, pudemos determinar que parte do problema vem dos dados originais do csvarquivo.

O problema pode ser resolvido usando o numpy/pythoncomando para exportar os dados T1:

np.savetxt('./hydrostat.csv', np.column_stack(( np.reshape(X, (lx*ly,1)), np.reshape(Y, (lx*ly,1)), np.reshape(T1.T, (lx*ly,1))  )), header='x, y, T', comments='# ',delimiter=',', newline='\n' )

Observe a presença dos dados transpostos com o arquivo T1.T.

O último ponto é usar y dir=reversepara obter a saída desejada com pgfplots.

Versão longa

Se eu usar o numpy/pythoncódigo para exportar os dados (sem transpor):

np.savetxt('./hydrostat.csv', np.column_stack(( np.reshape(X, (lx*ly,1)), np.reshape(Y, (lx*ly,1)),  np.reshape(T1, (lx*ly,1))  )), header='x, y, T', comments='# ',delimiter=',', newline='\n' )

Obtenho o seguinte arquivo hydrostat.csvpresente no link da pergunta ou na resposta de Ulrich.

Em seguida, usando o seguinte código LaTeX:

\documentclass[12pt]{standalone} 
\usepackage[T1]{fontenc}
\usepackage{tikz}                       % 
\usepackage{pgfplots}                   %
    \pgfplotsset{compat=newest}         %


\begin{document}
\begin{tikzpicture} 
    \begin{axis}[colormap/viridis,
                enlarge y limits=false,
                axis equal image,
                axis on top,
                colorbar,
                y dir=reverse,
            ]           

        \addplot[ 
                matrix plot*, point meta=explicit, mesh/cols=10,
            ]
            table[x expr=\thisrow{x}, y expr=\thisrow{y}, 
                            meta=T, ignore chars={\#}, col sep=comma,
                 ] 
            {hydrostat.csv};

    \end{axis}  
\end{tikzpicture}
\end{document}

Obterei a imagem resultante:

Adicionei um círculo vermelho para destacar o problema. Mesmo que a razão de aspecto seja o inverso do desejado (isto pode ser resolvido usando a solução de Ulrich), nesta área os dados são diferentes da matplotlibimagem.

Então, se eu usar o numpy/pythoncódigo (com a transposição):

np.savetxt('./hydrostat.csv', np.column_stack(( np.reshape(X, (lx*ly,1)), np.reshape(Y, (lx*ly,1)),  np.reshape(T1.T, (lx*ly,1))  )), header='x, y, T', comments='# ',delimiter=',', newline='\n' )

Vou obter o arquivo hydrostat.csv:

# x, y, T
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Então, usando o código LaTeX:

\documentclass[12pt]{standalone} 
\usepackage[T1]{fontenc}
\usepackage{tikz}                       % 
\usepackage{pgfplots}                   %
    \pgfplotsset{compat=newest}         %


\begin{document}
\begin{tikzpicture} 
    \begin{axis}[colormap/viridis,
                enlarge y limits=false,
                axis equal image,
                axis on top,
                colorbar,
                y dir=reverse,
            ]           

        \addplot[ 
                matrix plot*, point meta=explicit, mesh/cols=10,
            ]
            table[x expr=\thisrow{y}, y expr=\thisrow{x}, 
                            meta=T, ignore chars={\#}, col sep=comma,
                 ] 
            {hydrostat.csv};

    \end{axis}  
\end{tikzpicture}
\end{document}

Finalmente obtenho o resultado desejado: