如何基于0.1间隔分箱从计数数据绘制柱状图（解决Matplotlib报错）

问题描述 #

我有如下Pandas DataFrame：

import pandas as pd

df = {'count1': [2.2336, 2.2454, 2.2538, 2.2716999999999996, 2.2798000000000003, 2.2843, 2.2906, 2.2969, 2.3223000000000003, 2.3282, 2.3356999999999997, 2.3544, 2.3651999999999997, 2.3727, 2.3775, 2.3823000000000003, 2.392, 2.4051, 2.4092, 2.4133, 2.4168000000000003, 2.4175, 2.4209, 2.4392, 2.4476, 2.456, 2.461, 2.4723, 2.4776, 2.4882, 2.4989, 2.5095, 2.5221999999999998, 2.5318, 2.5422, 2.5494, 2.559, 2.5654, 2.5814, 2.5878, 2.6238, 2.6178000000000003, 2.624, 2.6303, 2.6366, 2.6425, 2.6481999999999997, 2.6525, 2.6553, 2.663, 2.6712, 2.6898, 2.7051, 2.7144, 2.727, 2.7416, 2.7472, 2.7512, 2.7557, 2.7574, 2.7594000000000003, 2.7636, 2.7699000000000003, 2.7761, 2.7809, 2.7855, 2.7902, 2.7948000000000004, 2.7995, 2.8043, 2.815, 2.8249, 2.8352, 2.8455, 2.8708, 2.8874, 2.9004000000000003, 2.9301, 2.9399, 2.9513000000000003, 2.9634, 2.9745999999999997, 2.9852, 2.9959000000000002, 3.0037, 3.0093, 3.015, 3.0184, 3.0206, 3.0225, 3.0245, 3.0264, 3.0282, 3.0305999999999997, 3.0331, 3.0334, 3.0361, 3.0388, 3.0418000000000003, 3.0443000000000002, 3.0463, 3.0464, 3.0481, 3.0496999999999996, 3.0514, 3.0530999999999997, 3.0544000000000002, 3.0556, 3.0569, 3.0581, 3.0623, 3.0627, 3.0633000000000004, 3.0638, 3.0643000000000002, 3.0648, 3.0652, 3.0656999999999996, 3.0663, 3.0675, 3.0682, 3.0688, 3.0695, 3.0702, 3.0721, 3.0741, 3.0761, 3.078, 3.08, 3.082, 3.0839000000000003, 3.0859, 3.0879000000000003, 3.0898000000000003, 3.0918, 3.0938000000000003, 3.0994, 3.1050999999999997, 3.1144000000000003, 3.1613, 3.1649000000000003, 3.1752, 3.1869, 3.1899, 3.1925, 3.1976, 3.2001, 3.2051999999999996, 3.2098, 3.2123000000000004],
      'count2': [3144, 3944, 7888, 4428, 68874, 5480, 56697, 20560, 8744, 91190, 352, 924, 1308611, 480, 51146, 170373, 58792, 11424, 1288673, 1845105, 401464, 657930, 1361172, 199373, 19753, 39082, 776, 7533, 9289, 36731, 53865, 100140, 59274, 35740, 2648, 144998, 78616, 848241, 34579, 216591, 22512, 4024, 17168, 1552, 13760, 8344, 65589, 43104, 44672, 917115, 16256, 4168, 29679, 22571, 7720, 452, 8836, 6888, 18578, 5148, 9289, 442, 214, 485, 3164, 1101, 1010, 9048, 293, 1628, 960, 517, 2362, 1262, 1524, 1173, 1348, 1288, 25568, 8416, 5792, 4944, 504, 4696, 2336, 458, 453, 1220, 1149, 6688, 6956, 7324, 7100, 7784, 5650, 5076, 5336, 6792, 5212, 4592, 5260, 1279, 654, 842, 990, 782, 1412, 1363, 935, 996, 775, 1471, 1525, 1398, 1097, 1082, 1668, 1007, 497, 598, 645, 698, 541, 504, 549, 540, 1568, 514, 578, 2906, 4360, 3916, 11944, 1434, 1589, 732, 641, 477, 307, 1884, 3232, 2408, 1016, 332, 139, 344, 4784, 1784, 1324, 204]}

df = pd.DataFrame(df)

我想绘制以count1为X轴、count2为Y轴的柱状图，分箱间隔0.1，尝试了以下代码：

import matplotlib.pyplot as plt

plt.bar(x=df['count1'], y=df['count2'], width=0.1)

但报错：

TypeError: bar() missing 1 required positional argument: 'height'

我的目标是复现R代码生成的图表效果，R代码如下：

ggplot(df, aes(x= count1, 
               y= count2)) + 
  geom_col() +
  ylim(0, 2000000) +
  scale_x_binned()

该R代码生成的图表为：X轴按0.1间隔分箱，每个箱对应一个柱子，柱子高度是该箱内所有count2值的总和，Y轴范围0到2000000。

解决方案 #

1. 报错原因分析 #

Matplotlib的plt.bar()函数中，Y轴高度对应的参数是height，不是y。你误用了参数名导致报错，但更关键的是，直接用原始数据绘制无法实现分箱求和的效果，需要先对数据进行分箱处理。

2. 分箱求和与绘图步骤 #

要实现R代码的效果，需先对count1按0.1间隔分箱，再分组计算每个箱内count2的总和，最后绘制柱状图。

完整代码：

import pandas as pd
import matplotlib.pyplot as plt

# 1. 创建0.1间隔的分箱区间
min_val = df['count1'].min()
max_val = df['count1'].max()
bins = pd.interval_range(start=min_val, end=max_val + 0.1, freq=0.1)
df['count1_bin'] = pd.cut(df['count1'], bins=bins)

# 2. 按分箱分组，计算count2的总和
binned_df = df.groupby('count1_bin')['count2'].sum().reset_index()

# 3. 格式化分箱标签，优化X轴显示
binned_df['bin_label'] = binned_df['count1_bin'].apply(lambda x: f"{x.left:.1f}-{x.right:.1f}")

# 4. 绘制柱状图并配置样式
plt.figure(figsize=(12,6))
plt.bar(x=binned_df['bin_label'], height=binned_df['count2'], width=0.8)

# 匹配R代码的视觉参数
plt.ylim(0, 2000000)
plt.xlabel('count1 (分箱间隔0.1)')
plt.ylabel('count2 总和')
plt.title('分箱柱状图')
plt.xticks(rotation=45)
plt.tight_layout()

plt.show()

代码说明 #

• 分箱处理：用pd.interval_range生成0.1间隔的分箱区间，再通过pd.cut为每个count1值分配对应箱。
• 分组求和：按分箱分组后对count2求和，得到每个箱对应的柱子高度。
• 标签格式化：将区间对象转换为易读的字符串标签，避免X轴显示混乱。
• 图表配置：设置Y轴范围、旋转X轴标签、调整布局，完全匹配R代码的输出效果。

内容的提问来源于stack exchange，提问作者EVS_93