如何将Pandas数据帧/系列数据保存为数字？

Question

这听起来有点奇怪,但我需要将Pandas控制台输出字符串保存到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 

有没有什么方法df.output_as_png(filename='df_data.png')可以生成一个只显示上面内容的图片文件？

Answer 1

您必须使用DataFrame.plot()命令返回的数字:

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

Answer 2

我使用matplotlib表功能,还有一些额外的样式:

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

我对我正在做的项目有同样的要求。但没有一个答案符合我的要求。这是最终对我有帮助的东西，并且可能对使用 Bokeh 的情况有用：

from bokeh.io import export_png, export_svgs
from bokeh.models import ColumnDataSource, DataTable, TableColumn

def save_df_as_image(df, path):
    source = ColumnDataSource(df)
    df_columns = [df.index.name]
    df_columns.extend(df.columns.values)
    columns_for_table=[]
    for column in df_columns:
        columns_for_table.append(TableColumn(field=column, title=column))

    data_table = DataTable(source=source, columns=columns_for_table,height_policy="auto",width_policy="auto",index_position=None)
    export_png(data_table, filename = path)

示例输出：

Answer 4

我有兴趣将数据框另存为表格以作为报告的附录。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()