用垂直线绘制熊猫数据框

Question

I want to plot a dataframe where each data point is not represented as a point but a vertical line from the zero axis like :

df['A'].plot(style='xxx')

where xxx is the style I need.

Also ideally i would like to be able to color each bar based on the values in another column in my dataframe.

I precise that my x axis values are numbers and are not equally spaced.

Answer 1

The pandas plotting tools are convenient wrappers to matplotlib. There is no way I know of to get the functionality you want directly via pandas.

You can get it in a few lines of matplotlib. Most of the code is to do the colour mapping:

import pandas as pd
import matplotlib.pyplot as plt
import numpy as np
import matplotlib.colors as colors
import matplotlib.cm as cmx

#make the dataframe
a = np.random.rand(100)    
b = np.random.ranf(100)    
df = pd.DataFrame({'a': a, 'b': b})

# do the colour mapping
c_norm  = colors.Normalize(vmin=min(df.b), vmax=max(df.b))
scalar_map = cmx.ScalarMappable(norm=c_norm, cmap=plt.get_cmap('jet'))    
color_vals = [scalar_map.to_rgba(val) for val in df.b]

# make the plot
plt.vlines(df.index, np.zeros_like(df.a), df.a, colors=color_vals)

I've used the DataFrame index for the x axis values but there is no reason that you could not use irregularly spaced x values.