如何将Pandas dataframe/series数据保存为图像？

Question

听起来有点奇怪，但我需要将Pandas控制台输出字符串保存为png图片。例如：

>>> df
                   sales  net_pft     ROE    ROIC
STK_ID RPT_Date                                  
600809 20120331  22.1401   4.9253  0.1651  0.6656
       20120630  38.1565   7.8684  0.2567  1.0385
       20120930  52.5098  12.4338  0.3587  1.2867
       20121231  64.7876  13.2731  0.3736  1.2205
       20130331  27.9517   7.5182  0.1745  0.3723
       20130630  40.6460   9.8572  0.2560  0.4290
       20130930  53.0501  11.8605  0.2927  0.4369 

有没有类似df.output_as_png(filename='df_data.png')的方法来生成一个pic文件，该文件只在内部显示上面的内容？

Answer 1

我有兴趣将我的数据框架保存为报表的附录表。我发现这是最简单的解决方案：

import pandas as pd
from matplotlib.backends.backend_pdf import PdfPages
import matplotlib.pyplot as plt

# Assuming that you have a dataframe, df
pp = PdfPages('Appendix_A.pdf')
total_rows, total_cols = df.shape; #There were 3 columns in my df

rows_per_page = 40; # Assign a page cut off length
rows_printed = 0
page_number = 1;

while (total_rows >0): 
    #put the table on a correctly sized figure    
    fig=plt.figure(figsize=(8.5, 11))
    plt.gca().axis('off')
    matplotlib_tab = pd.tools.plotting.table(plt.gca(),df.iloc[rows_printed:rows_printed+rows_per_page], 
        loc='upper center', colWidths=[0.2, 0.2, 0.2])    

    # Give you cells some styling 
    table_props=matplotlib_tab.properties()
    table_cells=table_props['child_artists'] # I have no clue why child_artists works
    for cell in table_cells:
        cell.set_height(0.024)
        cell.set_fontsize(12)

    # Add a header and footer with page number 
    fig.text(4.25/8.5, 10.5/11., "Appendix A", ha='center', fontsize=12)
    fig.text(4.25/8.5, 0.5/11., 'A'+str(page_number), ha='center', fontsize=12)

    pp.savefig()
    plt.close()

    #Update variables
    rows_printed += rows_per_page;
    total_rows -= rows_per_page;
    page_number+=1;

pp.close()

Answer 2

我将使用matplotlib表功能，并添加一些样式：

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import six

df = pd.DataFrame()
df['date'] = ['2016-04-01', '2016-04-02', '2016-04-03']
df['calories'] = [2200, 2100, 1500]
df['sleep hours'] = [2200, 2100, 1500]
df['gym'] = [True, False, False]

def render_mpl_table(data, col_width=3.0, row_height=0.625, font_size=14,
                     header_color='#40466e', row_colors=['#f1f1f2', 'w'], edge_color='w',
                     bbox=[0, 0, 1, 1], header_columns=0,
                     ax=None, **kwargs):
    if ax is None:
        size = (np.array(data.shape[::-1]) + np.array([0, 1])) * np.array([col_width, row_height])
        fig, ax = plt.subplots(figsize=size)
        ax.axis('off')

    mpl_table = ax.table(cellText=data.values, bbox=bbox, colLabels=data.columns, **kwargs)

    mpl_table.auto_set_font_size(False)
    mpl_table.set_fontsize(font_size)

    for k, cell in six.iteritems(mpl_table._cells):
        cell.set_edgecolor(edge_color)
        if k[0] == 0 or k[1] < header_columns:
            cell.set_text_props(weight='bold', color='w')
            cell.set_facecolor(header_color)
        else:
            cell.set_facecolor(row_colors[k[0]%len(row_colors) ])
    return ax

render_mpl_table(df, header_columns=0, col_width=2.0)

Answer 3

必须使用DataFrame.plot()命令返回的图形：

ax = df.plot()
fig = ax.get_figure()
fig.savefig('asdf.png')