Recently, we need to draw function diagrams for some data, because the requirements are not very high. I hope to draw a diagram as soon as possible, and I don't want to install any special software. I just use the python drawing package matplotlib to do it, which is convenient and fast, and the drawing is not bad. Here is a brief record.

There are two steps to draw a graph: 1. Prepare data; 2. Draw and display. Here's the code. It's easy to see the function of each part

#!/usr/bin/env python
# coding=utf-8

import platform
import matplotlib
from matplotlib.font_manager import *

sysstr = platform.system()
if(sysstr == "Windows"):   # Chinese character processing in windows
    myfont = FontProperties(fname='C:\Windows\Fonts\simhei.ttf')  #Choose the appropriate font file here
else:   # Chinese character processing under linux
    import sys
    reload(sys)
    sys.setdefaultencoding('utf-8')
    matplotlib.use('Agg')   #If you do not install x11 on the server, you can output the picture and save it, otherwise you may report an error
    myfont = FontProperties(fname='/usr/share/fonts/truetype/wqy/wqy-microhei.ttc')  #Choose the appropriate font file here
matplotlib.rcParams['axes.unicode_minus'] = False
	
import matplotlib.pyplot as plt
import numpy as np

# Define the variables used
timebar = []
absolute = []
basevalue = 1000000.0
index = []
relativeMax = []
period = 30

idx = 0
#Read variables in from the file and put them in the appropriate variables
for line in open("pnl.txt",'r'):
    row = line.split('\t')
    timebar.append(int(row[0]))
    value = float(row[2])/basevalue
    absolute.append(value)
    if (idx % period == 0):  #The value is counted periodically here
        index.append(idx)
        relativeMax.append(basevalue-min(absolute))
    idx+=1

#Drawing
fig1 = plt.figure()
plt.title("curve",fontproperties=myfont)   #Name of the entire coordinate chart
plt.xlabel('timebar')   #x axis name
plt.ylabel('absolute')   #y axis name
plt.plot(timebar,absolute)
fig1.savefig("curve.png")  #Save pictures
plt.show()   #display picture

#Write periodic statistics to file
with open("summary.txt",'w') as summaryFile:
    i = 0
    for idx in index:
        output = "{0},{1:.2%},{2:.2%}\n".format(i,absolute[idx],relativeMax[i])
        summaryFile.write(output)
        i+=1

The pnl.txt file is as follows:

1524096000      10000.154785    1010000.154785 
1524182400      2988.606417     1012988.761203
1524268800      -3999.066491    1008989.694711
1524355200      -2212.860282    1006776.834429
...
...
...