问题
I have a dataset like this:
Freq
Date
01-11 1
05-11 1
04-10 1
02-12 1
12-10 1
... ...
07-20 286
06-20 288
05-20 390
04-20 471
03-20 510
I would like to plot the frequency by month, to create 12 plots one per each month, showing the frequency through through years. My approach would be: use groupby to group all the months, then plot the histogram of frequency. But I have encountered a difficulty regarding how to extract months from Date. I have tried as follows:
df.groupby(df['Date'].dt.strftime('%m')).size().sort_values()
and then I used plot(kind=bar), trying to apply this once per each month. But the output is different from that expected.
回答1:
IIUC, I think want to reshape you dataframe like this:
import matplotlib.pyplot as plt
import pandas as pd
import numpy as np
s = pd.Series(np.random.randint(0,100, 120), index=pd.date_range('1/1/2010',periods=120, freq='MS'))
df = s.reset_index()
df['Year'] = df['index'].dt.year
df['month'] = df['index'].dt.month
ax = df.set_index(['Year', 'month'])[0].unstack('month').plot.bar(subplots=True, layout=(4,3), figsize=(15,10))
plt.suptitle('Values by Months of the Year over Ten-year period');
Chart:
Input dataframe for chart:
print(df.set_index(['Year', 'month'])[0].unstack('month'))
Years on index and months as columns:
month 1 2 3 4 5 6 7 8 9 10 11 12
Year
2010 85 63 68 35 3 77 14 72 78 26 52 61
2011 47 92 37 89 24 62 76 10 88 6 48 77
2012 51 6 27 92 90 6 76 69 45 55 8 7
2013 45 45 53 29 32 13 23 39 82 68 83 41
2014 46 0 53 33 92 62 49 54 39 51 19 20
2015 55 81 95 67 75 93 92 94 67 72 40 26
2016 9 44 36 89 28 92 25 52 80 32 88 37
2017 52 60 0 34 9 72 70 42 88 18 51 3
2018 96 79 83 60 56 12 8 54 57 68 9 69
2019 32 98 47 23 35 28 59 81 86 32 50 52
来源：https://stackoverflow.com/questions/64617608/plot-through-time-setting-specific-filtering