"plot '%s' with lines, '%s' with points;" % (eout,nout)
其中'eout'和'nout'是两个文件名。
PS：我更喜欢不使用额外的Python模块（例如gnuplot-py），仅使用标准API。
谢谢你
使用subprocess模块可以调用其他程序：
import subprocess
plot = subprocess.Popen(['gnuplot'], stdin=subprocess.PIPE)
plot.communicate("plot '%s' with lines, '%s' with points;" % (eout,nout))
plot.returncode 是否有错误。 - sth在Doug Hellemann的Python Module of the Week中对Subprocess有非常清晰的解释。
这个很有效：
import subprocess
proc = subprocess.Popen(['gnuplot','-p'],
shell=True,
stdin=subprocess.PIPE,
)
proc.stdin.write('set xrange [0:10]; set yrange [-2:2]\n')
proc.stdin.write('plot sin(x)\n')
proc.stdin.write('quit\n') #close the gnuplot window
proc.stdin.flush()
如果使用“communicate”，则绘图窗口会立即关闭，除非使用gnuplot暂停命令。
proc.communicate("""
set xrange [0:10]; set yrange [-2:2]
plot sin(x)
pause 4
""")
shell=False 和 gnuplot 的 --persist。 - sdaau一种简单的方法是编写第三个文件，其中包含您的gnuplot命令，然后告诉Python使用该文件执行gnuplot。假设您编写了：
"plot '%s' with lines, '%s' with points;" % (eout,nout)
将内容保存至名为 tmp.gp 的文件中。然后您可以使用
from os import system, remove
system('gnuplot -persist tmp.gp')
remove('tmp.gp')
我尝试做类似的事情，但是我想从Python中提取数据并将图形文件作为变量输出（因此数据和图形都不是实际文件）。这是我想出来的方法：
#! /usr/bin/env python
import subprocess
from sys import stdout, stderr
from os import linesep as nl
def gnuplot_ExecuteCommands(commands, data):
args = ["gnuplot", "-e", (";".join([str(c) for c in commands]))]
program = subprocess.Popen(\
args, \
stdin=subprocess.PIPE, \
stdout=subprocess.PIPE, \
stderr=subprocess.PIPE, \
)
for line in data:
program.stdin.write(str(line)+nl)
return program
def gnuplot_GifTest():
commands = [\
"set datafile separator ','",\
"set terminal gif",\
"set output",\
"plot '-' using 1:2 with linespoints, '' using 1:2 with linespoints",\
]
data = [\
"1,1",\
"2,2",\
"3,5",\
"4,2",\
"5,1",\
"e",\
"1,5",\
"2,4",\
"3,1",\
"4,4",\
"5,5",\
"e",\
]
return (commands, data)
if __name__=="__main__":
(commands, data) = gnuplot_GifTest()
plotProg = gnuplot_ExecuteCommands(commands, data)
(out, err) = (plotProg.stdout, plotProg.stderr)
stdout.write(out.read())
那个脚本在main函数的最后一步将图形输出到标准输出。等效的命令行（将图形管道传输至'out.gif'）如下：
gnuplot -e "set datafile separator ','; set terminal gif; set output; plot '-' using 1:2 with linespoints, '' using 1:2 with linespoints" > out.gif
1,1
2,2
3,5
4,2
5,1
e
1,5
2,4
3,1
4,4
5,5
e
当我从celery任务计算图表时发现，从stdout读取数据会导致程序锁定。因此，我采用了Ben的建议，重新设计了代码，使用StringIO创建了将要输入到stdin的文件，并使用subprocess.communicate从stdout立即获取结果，无需读取。
from subprocess import Popen, PIPE
from StringIO import StringIO
from os import linesep as nl
def gnuplot(commands, data):
""" drive gnuplot, expects lists, returns stdout as string """
dfile = StringIO()
for line in data:
dfile.write(str(line) + nl)
args = ["gnuplot", "-e", (";".join([str(c) for c in commands]))]
p = Popen(args, stdin=PIPE, stdout=PIPE, stderr=PIPE)
dfile.seek(0)
return p.communicate(dfile.read())[0]
def gnuplot_GifTest():
commands = [\
"set datafile separator ','",\
"set terminal gif",\
"set output",\
"plot '-' using 1:2 with linespoints, '' using 1:2 with linespoints",\
]
data = [\
"1,1",\
"2,2",\
"3,5",\
"4,2",\
"5,1",\
"e",\
"1,5",\
"2,4",\
"3,1",\
"4,4",\
"5,5",\
"e",\
]
return (commands, data)
if __name__=="__main__":
(commands, data) = gnuplot_GifTest()
print gnuplot(commands, data)
这里有一个提供wgnuplot.exe接口的类:
from ctypes import *
import time
import sys
import os
#
# some win32 constants
#
WM_CHAR = 0X0102
WM_CLOSE = 16
SW_HIDE = 0
STARTF_USESHOWWINDOW = 1
WORD = c_ushort
DWORD = c_ulong
LPBYTE = POINTER(c_ubyte)
LPTSTR = POINTER(c_char)
HANDLE = c_void_p
class STARTUPINFO(Structure):
_fields_ = [("cb",DWORD),
("lpReserved",LPTSTR),
("lpDesktop", LPTSTR),
("lpTitle", LPTSTR),
("dwX", DWORD),
("dwY", DWORD),
("dwXSize", DWORD),
("dwYSize", DWORD),
("dwXCountChars", DWORD),
("dwYCountChars", DWORD),
("dwFillAttribute", DWORD),
("dwFlags", DWORD),
("wShowWindow", WORD),
("cbReserved2", WORD),
("lpReserved2", LPBYTE),
("hStdInput", HANDLE),
("hStdOutput", HANDLE),
("hStdError", HANDLE),]
class PROCESS_INFORMATION(Structure):
_fields_ = [("hProcess", HANDLE),
("hThread", HANDLE),
("dwProcessId", DWORD),
("dwThreadId", DWORD),]
#
# Gnuplot
#
class Gnuplot:
#
# __init__
#
def __init__(self, path_to_exe):
# open gnuplot
self.launch(path_to_exe)
# wait till it's ready
if(windll.user32.WaitForInputIdle(self.hProcess, 1000)):
print "Error: Gnuplot timeout!"
sys.exit(1)
# get window handles
self.hwndParent = windll.user32.FindWindowA(None, 'gnuplot')
self.hwndText = windll.user32.FindWindowExA(self.hwndParent, None, 'wgnuplot_text', None)
#
# __del__
#
def __del__(self):
windll.kernel32.CloseHandle(self.hProcess);
windll.kernel32.CloseHandle(self.hThread);
windll.user32.PostMessageA(self.hwndParent, WM_CLOSE, 0, 0)
#
# launch
#
def launch(self, path_to_exe):
startupinfo = STARTUPINFO()
process_information = PROCESS_INFORMATION()
startupinfo.dwFlags = STARTF_USESHOWWINDOW
startupinfo.wShowWindow = SW_HIDE
if windll.kernel32.CreateProcessA(path_to_exe, None, None, None, False, 0, None, None, byref(startupinfo), byref(process_information)):
self.hProcess = process_information.hProcess
self.hThread = process_information.hThread
else:
print "Error: Create Process - Error code: ", windll.kernel32.GetLastError()
sys.exit(1)
#
# execute
#
def execute(self, script, file_path):
# make sure file doesn't exist
try: os.unlink(file_path)
except: pass
# send script to gnuplot window
for c in script: windll.user32.PostMessageA(self.hwndText, WM_CHAR, ord(c), 1L)
# wait till gnuplot generates the chart
while( not (os.path.exists(file_path) and (os.path.getsize(file_path) > 0))): time.sleep(0.01)
以下是一个扩展之前回答的示例。这个解决方案需要Gnuplot 5.1，因为它使用了数据块。有关数据块的更多信息，请在gnuplot中执行help datablocks。
一些先前方法的问题在于plot '-' 会立即消耗紧随其后的数据。不能在随后的绘图命令中重复使用相同的数据。可以使用数据块来缓解此问题。使用数据块，我们可以模拟多个数据文件。例如，您可能希望使用两个数据文件中的数据绘制图形，例如plot "myData.dat" using 1:2 with linespoints, '' using 1:3 with linespoints, "myData2.dat" using 1:2 with linespoints。我们可以将这些数据直接提供给gnuplot，而不需要创建实际的数据文件。
import sys, subprocess
from os import linesep as nl
from subprocess import Popen, PIPE
def gnuplot(commands, data):
""" drive gnuplot, expects lists, returns stdout as string """
script= nl.join(data)+nl.join(commands)+nl
print script
args = ["gnuplot", "-p"]
p = Popen(args, shell=False, stdin=PIPE)
return p.communicate(script)[0]
def buildGraph():
commands = [\
"set datafile separator ','",\
"plot '$data1' using 1:2 with linespoints, '' using 1:3 with linespoints, '$data2' using 1:2 with linespoints",\
]
data = [\
"$data1 << EOD",\
"1,30,12",\
"2,40,15",\
"3,35,20",\
"4,60,21",\
"5,50,30",\
"EOD",\
"$data2 << EOD",\
"1,20",\
"2,40",\
"3,40",\
"4,50",\
"5,60",\
"EOD",\
]
return (commands, data)
def main(args):
(commands, data) = buildGraph()
print gnuplot(commands, data)
if __name__ == "__main__":
main(sys.argv[1:])
plot '-'更加灵活，因为它使得多次重复使用相同的数据变得更加容易，包括在同一条绘图命令中：https://dev59.com/imPVa4cB1Zd3GeqP4lN4#33064402请注意，这种方法要求在绘图命令之前将数据提供给gnuplot！return p.communicate(script.encode('utf-8'))[0]。 - terence hillset datafile separator ','，您可以使用任何分隔符，参见我上面的示例。 - Joris Kinable我来晚了，但因为让它正常工作花费了我一些时间，也许值得做个记录。这些程序在Windows上使用Python 3.3.2运行。
请注意，程序中到处都使用字节而不是字符串（例如b"plot x"，而不仅仅是"plot x"），但如果这是个问题，只需执行类似以下的操作即可：
"plot x".encode("ascii")
第一种解决方案：使用communicate发送所有内容，并在完成后关闭。不要忘记pause，否则窗口会立即关闭。但是，如果使用gnuplot将图像存储在文件中，则没有问题。
from subprocess import *
path = "C:\\app\\gnuplot\\bin\\gnuplot"
p = Popen([path], stdin=PIPE, stdout=PIPE)
p.communicate(b"splot x*y\npause 4\n")
第二种解决方案：使用stdin.write(...)一个接一个地发送命令，但是不要忘记刷新！（这是我最初没有做对的地方）并且在工作完成后使用terminate关闭连接和gnuplot。
from subprocess import *
path = "C:\\app\\gnuplot\\bin\\gnuplot"
p = Popen([path], stdin=PIPE, stdout=PIPE)
p.stdin.write(b"splot x*y\n")
p.stdin.flush()
...
p.stdin.write(b"plot x,x*x\n")
p.stdin.flush()
...
p.terminate()