TypeError：strptime（）参数1必须是str，而不是list

Question

I am trying to plot the following data:

01/01/2012 01:00
01/01/2012 02:00
01/01/2012 03:00
01/01/2012 04:00
01/01/2012 05:00
01/01/2012 06:00
01/01/2012 07:00
01/01/2012 08:00
01/01/2012 09:00
01/01/2012 10:00
01/01/2012 11:00
01/01/2012 12:00
01/01/2012 13:00
01/01/2012 14:00
01/01/2012 15:00
01/01/2012 16:00
01/01/2012 17:00
01/01/2012 18:00
01/01/2012 19:00
01/01/2012 20:00
01/01/2012 21:00
01/01/2012 22:00
01/01/2012 23:00
02/01/2012 00:00
04/01/2012 23:00
................
05/01/2012 00:00
05/01/2012 01:00
................ 

Against wind_speed data which is in the format:

 [ 3.30049159  2.25226244  1.44078451 ... 12.8397099   9.75722427
  7.98525797]

My code is:

    T = T[1:]
    print( datetime.datetime.strptime(T, "%m/%d/%Y %H:%M:%S").strftime("%Y%m%d %I:%M:%S") #pharsing the time
    TIMESTAMP = [str (i) for i in T]
    plt.plot_date(TIMESTAMP, wind_speed)
    plt.show()

However, I am receiving the error message "TypeError: strptime() argument 1 must be str", not list. I am new to Python and would appreciate help on how to either convert to the list to a string or another method on how to resolve this. Thank you!

Answer 1

As the other answers suggest, you require a different way, probably map . You may also use pd.to_datetime() and pass it the whole list. And then use the same as x-axis and the wind_speed for y-axis.

import pandas as pd    
timestamp = pd.to_datetime(T[1:])

It will create a DatetimeIndex which you can again format according to your needs, like:

timestamp = timestamp.strftime("%Y%m%d %I:%M:%S")

In one line:

timestamp = pd.to_datetime(T[1:]).strftime("%Y%m%d %I:%M:%S")

After having two lists for timestamp and wind_speed, use may use something like:

import matplotlib.pyplot as plt
fig, ax = plt.subplots(figsize=(13,6))
ax.plot(timestamp, wind_speed)
plt.xticks(rotation=30)
plt.show()

Answer 2

This should help. Using map with lambda to convert datetime to your required format.

Demo:

import datetime
data = ['01/01/2012 01:00', '01/01/2012 02:00', '01/01/2012 03:00', '01/01/2012 04:00', '01/01/2012 05:00', '01/01/2012 06:00', '01/01/2012 07:00', '01/01/2012 08:00', '01/01/2012 09:00', '01/01/2012 10:00', '01/01/2012 11:00', '01/01/2012 12:00', '01/01/2012 13:00', '01/01/2012 14:00', '01/01/2012 15:00', '01/01/2012 16:00', '01/01/2012 17:00', '01/01/2012 18:00', '01/01/2012 19:00', '01/01/2012 20:00', '01/01/2012 21:00', '01/01/2012 22:00', '01/01/2012 23:00', '02/01/2012 00:00', '04/01/2012 23:00']
data = list(map(lambda x: datetime.datetime.strptime(x,  "%m/%d/%Y %H:%M").strftime("%Y%m%d %I:%M:%S"), data))
print(data)

Output:

['20120101 01:00:00', '20120101 02:00:00', '20120101 03:00:00', '20120101 04:00:00', '20120101 05:00:00', '20120101 06:00:00', '20120101 07:00:00', '20120101 08:00:00', '20120101 09:00:00', '20120101 10:00:00', '20120101 11:00:00', '20120101 12:00:00', '20120101 01:00:00', '20120101 02:00:00', '20120101 03:00:00', '20120101 04:00:00', '20120101 05:00:00', '20120101 06:00:00', '20120101 07:00:00', '20120101 08:00:00', '20120101 09:00:00', '20120101 10:00:00', '20120101 11:00:00', '20120201 12:00:00', '20120401 11:00:00']

Answer 3

Your variable T is apparently a list of strings, not a string itself, so you need to iterate through T and pass the items in T to strptime instead.

for t in T:
    datetime.datetime.strptime(t, "%m/%d/%Y %H:%M:%S").strftime("%Y%m%d %I:%M:%S")