Python date formatting and plotting, python date plotting

Python date formatting and plotting, python date plotting

Drawing a curve of volume changes over time is a common requirement, for example, drawing a curve of the number of software users. Matplotlib. pyplot. plot_date (date, num) is the main function used to draw a curve that changes over time ). Since the first variable is of the datetime type, you must first format the string type data input.

1. Use strptime to format a string 1.1 Basic example

Time = datetime. datetime. strptime ('2017-12-28 13:49:30 ',' % Y-% m-% d % H: % M: % s ')

Print time

13:49:30

1.2 common formatting Mappings

The common ing relationships are shown in the following table (13:49:30). For more information, see format the time and date in python-go to dawn-blog

Year		Month		Day	Hour		Minute	Second
% Y	% Y	% M	% B	% D	% H	% I	% M	% S
14	2014	12	Dec	28	13	01	49	30

2. A specific drawing example

Count the number of first-time software installations in windows, and draw a scatter chart (by day) and a bar chart (by year)

import _winregimport datetimeimport matplotlib.datesimport matplotlib.pyplot import numpy as npprint "import winreg done!"key = _winreg.OpenKey(_winreg.HKEY_LOCAL_MACHINE,r"Software\Microsoft\Windows\CurrentVersion\Uninstall")#key = _winreg.OpenKey(_winreg.HKEY_CURRENT_USER,r"Software\Microsoft\Windows\CurrentVersion\Explorer")print keyall_software=[]k=0try:    i=0        while 1:        subkey_string=_winreg.EnumKey(key,i)        #print subkey_string        try:            j=0            temp={}            get_installDate=0            #some subkey may not have installdate subkey and value            while 1:                #subkey=_winreg.OpenKey(key,"InstallDate")                subkey=_winreg.OpenKey(key,subkey_string)                name, value, type_value = _winreg.EnumValue(subkey,j)                #print repr(name),repr(value)                #print "name is "+name                if name=="DisplayName":                    #print "Name equals DisplayName"                    temp["DisplayName"]=value                if name=="InstallDate":                    #print "Name equals installdate"                    temp["InstallDate"]=value                    get_installDate=1                j+=1        except WindowsError:            #print 'interruptted j='+str(j)            if get_installDate:                all_software.append(temp)        #print repr(name)        #print value        i +=1except WindowsError:    printfor item in range(len(all_software)):    all_software[item]["InstallDate"]=datetime.datetime.strptime(all_software[item]["InstallDate"].encode('ascii','ignore'),'%Y%m%d')count={}bar_by_year={}bar_by_year['2012']=0bar_by_year['2013']=0bar_by_year['2014']=0for item in all_software:    if count.has_key(item["InstallDate"]):        count[item["InstallDate"]]+=1    else:        count[item["InstallDate"]]=1    bar_by_year[str(item['InstallDate'].year)]+=1xvalues=[]yvalues=[]for key,value in count.iteritems():    xvalues.append(key)    yvalues.append(value)xvalues=matplotlib.dates.date2num(xvalues)matplotlib.pyplot.figure(1)matplotlib.pyplot.plot_date(xvalues,yvalues)matplotlib.pyplot.figure(2)xvalues_2=np.arange(3)yvalues_2=bar_by_year.values()fig2=matplotlib.pyplot.bar(xvalues_2,yvalues_2,0.5)matplotlib.pyplot.xticks(xvalues_2+0.25, ['2012','2013','2014'], rotation='vertical')matplotlib.pyplot.show()#value, type = _winreg.QueryValueEx(key, "EnableAutoTray")

 

 

Iii. References

[1] Python registry operations-normal-blog

[2] c ++-How can I enumerate/list all installed applications in Windows XP? -Stack Overflow

[3] winreg-Windows registry access-Python v3.0.1 documentation

[4] graph-plow.time in python with matplotlib-Stack Overflow

[5] Sha Hu Wang | matplotlib Plot 2

[6] Python Chart Drawing: matplotlib Drawing Library entry-diemeng Zhuangzhou-blog Park

[7] ticks_and_spines example code: ticklabels_demo_rotation.py-Matplotlib 1.4.2 documentation

[8] api example code: barchart_demo.py-Matplotlib 1.4.2 documentation