Python 日期顺序错误

Question

I was wondering why the x-axis plots the dates wrong, it begins at the 05/02 when it should start at the 30/01, and I'm not sure where it is I went wrong.

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

cols = ['Time','Water Usage']
A = pd.read_csv("CSVFile", names=cols, parse_dates=[0])

plt.ylabel = "Time"
plt.xlabel = "Water Usage"
A.plot(x='Time',y='Water Usage')
plt.show()

The file is in the format

30/01/2018 16:00:00 , 50091

05/02/2018 14:00:00, 50890

so ideally it should plot the 30/01 first followed by the 05/02, whereas currently its doing the opposite.

Answer 1

If you just need to reorder it in timely order, You can simply sort dataframe prior to plotting. You can use:

A = A.sort_index()

if the date column is set to be index. If not then following will do the trick:

A = A.set_index('date').sort_index().reset_index()

Since the index is of datetime type, it will automatically sort the whole dataframe