How can i plot line chart in python?

Question

i have a txt file . Here are some example rows:

computer 2015-11-26 08:47:00 86
computer 2015-11-26 08:48:00 78
computer 2015-11-26 08:49:00 61
computer 2015-11-26 08:50:00 50
computer 2015-11-26 08:51:00 53
computer 2015-11-26 08:52:00 61
computer 2015-11-26 08:53:00 60
computer 2015-11-26 08:54:00 50
computer 2015-11-26 08:55:00 91
computer 2015-11-26 08:56:00 99
computer 2015-11-26 08:57:00 75
computer 2015-11-26 08:58:00 105
computer 2015-11-26 08:59:00 67
computer 2015-11-26 09:00:00 63

I want to plot line chart like this:

like this

how can i do this?

i try this example, but i didnt do it

plt.bar()
        plt.xticks()
        plt.ylabel()
        plt.title()
        plt.savefig() 
        plt.show()

how can i devolop this code?

tmdavison · Accepted Answer · 2015-12-08 17:01:46Z

4

You can use pandas for parsing. Perhaps you can look into groupby functions of pandas to make the code better, but this is a working example (python 3.x)

import matplotlib.pyplot as plt
import pandas as pd

df = pd.read_csv('t.txt', delim_whitespace=True, header=None, parse_dates={'Dates': [1, 2]})

plt.figure()
l_h = []
for identifier in df[0].unique():
    h, = plt.plot(df[df[0]==identifier]['Dates'], df[df[0]==identifier][3], label=identifier)
    l_h.append(h)
plt.legend(handles=l_h)
plt.show()

edited Dec 8, 2015 at 17:01

tmdavison

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answered Dec 8, 2015 at 16:54

Maecky

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2 Comments

Nicqu Over a year ago

i must be use python 2.7

Maecky Over a year ago

this code also works in python 2.7. Just checked it... You must have matplotlib and pandas installed, which you can see from the import statements...

Community · Accepted Answer · 2017-05-23 12:09:08Z

This is done using matplotlib:

import matplotlib.dates as md
import datetime as dt
import matplotlib.pyplot as plt
import numpy as np
import re

computerData =[]
studentData = []
universityData = []
scienceData = []
timestamp1 = []
timestamp2 = []
timestamp3 = []
p = re.compile("^.*[a-z]. ([0-9].*) ([0-9]*)$")
f = open(r"t.txt")
for line in f:
    if line.startswith("computer"):
        t1 = p.search(line)
        dates1 = dt.datetime.strptime(t1.group(1), "%Y-%m-%d %H:%M:%S")
        time1 = md.date2num(dates1)
        timestamp1.append(time1)
        computerData.append(int(t1.group(2)))

    if line.startswith("student"):
        t2 = p.search(line)
        dates2 = dt.datetime.strptime(t2.group(1), "%Y-%m-%d %H:%M:%S")
        time2 = md.date2num(dates2)
        timestamp2.append(time2)
        studentData.append(int(t2.group(2)))

    if line.startswith("science"):
        t3 = p.search(line)
        dates3 = dt.datetime.strptime(t3.group(1), "%Y-%m-%d %H:%M:%S")
        time3 = md.date2num(dates3)
        timestamp3.append(time3)
        scienceData.append(int(t3.group(2)))

ax=plt.gca()
xfmt = md.DateFormatter('%H:%M')
ax.xaxis.set_major_formatter(xfmt)

plt.plot(timestamp1,computerData,'r', label="Computer", linewidth=2)
plt.plot(timestamp2,studentData,'g', label="Student", linewidth=2)
plt.plot(timestamp3,scienceData,'y', label="Science", linewidth=2)

plt.legend()
plt.grid(True,color='k')
plt.show()

Reference: To show timestamps on x-axis plotting unix timestamps in matplotlib

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