Gnuplot 输出设置为“在屏幕上”显示如何更改程序，以便将绘图输出定向到我在下面提供程序的文件夹
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【中文标题】Gnuplot 输出设置为“在屏幕上”显示如何更改程序，以便将绘图输出定向到我在下面提供程序的文件夹【英文标题】：The Gnuplot output is set to display 'onscreen' how to change the program so that plot output is directed to a folder I am providing the program below 【发布时间】：2018-05-25 18:30:53 【问题描述】：从下面的代码可以预测 ROC 的准确度值，并使用 GNUplot 来显示绘图输出。但输出设置为“屏幕上”。因此，情节只出现几秒钟并关闭。我想将绘图输出定向到一个文件夹。如何修改代码。
感谢您的帮助。
程序取自 plotroc.py https://www.csie.ntu.edu.tw/~cjlin/libsvmtools/#roc_curve_for_binary_svm
#!/usr/bin/env python
#This tool allow users to plot SVM-prob ROC curve from data
from svmutil import *
from sys import argv, platform
from os import path, popen
from random import randrange , seed
from operator import itemgetter
from time import sleep
#search path for gnuplot executable
#be careful on using windows LONG filename, surround it with double quotes.
#and leading 'r' to make it raw string, otherwise, repeat \\.
gnuplot_exe_list = [r'"C:\Users\Lakshmi\Documents\gnuplot\bin\pgnuplot.exe"', "/usr/bin/gnuplot","/usr/local/bin/gnuplot"]
def get_pos_deci(train_y, train_x, test_y, test_x, param):
model = svm_train(train_y, train_x, param)
#predict and grab decision value, assure deci>0 for label+,
#the positive descision value = val[0]*labels[0]
labels = model.get_labels()
py, evals, deci = svm_predict(test_y, test_x, model)
deci = [labels[0]*val[0] for val in deci]
return deci,model
#get_cv_deci(prob_y[], prob_x[], svm_parameter param, nr_fold)
#input raw attributes, labels, param, cv_fold in decision value building
#output list of decision value, remember to seed(0)
def get_cv_deci(prob_y, prob_x, param, nr_fold):
if nr_fold == 1 or nr_fold==0:
deci,model = get_pos_deci(prob_y, prob_x, prob_y, prob_x, param)
return deci
deci, model = [], []
prob_l = len(prob_y)
#random permutation by swapping i and j instance
for i in range(prob_l):
j = randrange(i,prob_l)
prob_x[i], prob_x[j] = prob_x[j], prob_x[i]
prob_y[i], prob_y[j] = prob_y[j], prob_y[i]
#cross training : folding
for i in range(nr_fold):
begin = i * prob_l // nr_fold
end = (i + 1) * prob_l // nr_fold
train_x = prob_x[:begin] + prob_x[end:]
train_y = prob_y[:begin] + prob_y[end:]
test_x = prob_x[begin:end]
test_y = prob_y[begin:end]
subdeci, submdel = get_pos_deci(train_y, train_x, test_y, test_x, param)
deci += subdeci
return deci
#a simple gnuplot object
class gnuplot:
def __init__(self, term='onscreen'):
# -persists leave plot window on screen after gnuplot terminates
if platform == 'win32':
cmdline = gnuplot_exe
self.__dict__['screen_term'] = 'windows'
else:
cmdline = gnuplot_exe + ' -persist'
self.__dict__['screen_term'] = 'x11'
self.__dict__['iface'] = popen(cmdline,'w')
self.set_term(term)
def set_term(self, term):
if term=='onscreen':
self.writeln("set term %s" % self.screen_term)
else:
#term must be either x.ps or x.png
if term.find('.ps')>0:
self.writeln("set term postscript eps color 22")
elif term.find('.png')>0:
self.writeln("set term png")
else:
print("You must set term to either *.ps or *.png")
raise SystemExit
self.output = term
def writeln(self,cmdline):
self.iface.write(cmdline + '\n')
def __setattr__(self, attr, val):
if type(val) == str:
self.writeln('set %s \"%s\"' % (attr, val))
else:
print("Unsupport format:", attr, val)
raise SystemExit
#terminate gnuplot
def __del__(self):
self.writeln("quit")
self.iface.flush()
self.iface.close()
def __repr__(self):
return "<gnuplot instance: output=%s>" % term
#data is a list of [x,y]
def plotline(self, data):
self.writeln("plot \"-\" notitle with lines linewidth 1")
for i in range(len(data)):
self.writeln("%f %f" % (data[i][0], data[i][1]))
sleep(0) #delay
self.writeln("e")
if platform=='win32':
sleep(3)
#processing argv and set some global variables
def proc_argv(argv = argv):
#print("Usage: %s " % argv[0])
#The command line : ./plotroc.py [-v cv_fold | -T testing_file] [libsvm-options] training_file
train_file = argv[-1]
test_file = None
fold = 5
options = []
i = 1
while i < len(argv)-1:
if argv[i] == '-T':
test_file = argv[i+1]
i += 1
elif argv[i] == '-v':
fold = int(argv[i+1])
i += 1
else :
options += [argv[i]]
i += 1
return ' '.join(options), fold, train_file, test_file
def plot_roc(deci, label, output, title):
#count of postive and negative labels
db = []
pos, neg = 0, 0
for i in range(len(label)):
if label[i]>0:
pos+=1
else:
neg+=1
db.append([deci[i], label[i]])
#sorting by decision value
db = sorted(db, key=itemgetter(0), reverse=True)
#calculate ROC
xy_arr = []
tp, fp = 0., 0. #assure float division
for i in range(len(db)):
if db[i][1]>0: #positive
tp+=1
else:
fp+=1
xy_arr.append([fp/neg,tp/pos])
#area under curve
aoc = 0.
prev_x = 0
for x,y in xy_arr:
if x != prev_x:
aoc += (x - prev_x) * y
prev_x = x
#begin gnuplot
if title == None:
title = output
#also write to file
g = gnuplot(output)
g.xlabel = "False Positive Rate"
g.ylabel = "True Positive Rate"
g.title = "ROC curve of %s (AUC = %.4f)" % (title,aoc)
g.plotline(xy_arr)
#display on screen
s = gnuplot('onscreen')
s.xlabel = "False Positive Rate"
s.ylabel = "True Positive Rate"
s.title = "ROC curve of %s (AUC = %.4f)" % (title,aoc)
s.plotline(xy_arr)
def check_gnuplot_exe():
global gnuplot_exe
gnuplot_exe = None
for g in gnuplot_exe_list:
if path.exists(g.replace('"','')):
gnuplot_exe=g
break
if gnuplot_exe == None:
print("You must add correct path of 'gnuplot' into gnuplot_exe_list")
raise SystemExit
def main():
check_gnuplot_exe()
if len(argv) <= 1:
print("Usage: %s [-v cv_fold | -T testing_file] [libsvm-options] training_file" % argv[0])
raise SystemExit
param,fold,train_file,test_file = proc_argv()
output_file = path.split(train_file)[1] + '-roc.png'
#read data
train_y, train_x = svm_read_problem(train_file)
if set(train_y) != set([1,-1]):
print("ROC is only applicable to binary classes with labels 1, -1")
raise SystemExit
#get decision value, with positive = label+
seed(0) #reset random seed
if test_file: #go with test_file
output_title = "%s on %s" % (path.split(test_file)[1], path.split(train_file)[1])
test_y, test_x = svm_read_problem(test_file)
if set(test_y) != set([1,-1]):
print("ROC is only applicable to binary classes with labels 1, -1")
raise SystemExit
deci,model = get_pos_deci(train_y, train_x, test_y, test_x, param)
plot_roc(deci, test_y, output_file, output_title)
else: #single file -> CV
output_title = path.split(train_file)[1]
deci = get_cv_deci(train_y, train_x, param, fold)
plot_roc(deci, train_y, output_file, output_title)
if __name__ == '__main__':
main()`
【问题讨论】：
再次读取代码 - 有字符串*.png 和变量 output_file。我怀疑它会为某个文件生成图像，然后在屏幕上显示它
使用print()显示output_file中的路径
我使用'import os print os.path.abspath("output_file")' 打印了一个路径，但在路径中找不到这样的输出文件
你用它做什么用的？
我想打印输出文件的位置
【参考方案1】：
我下载了代码和数据文件heart_scale并运行后
python script.py -v 5 -c 10 heart_scale
我在执行脚本的文件夹中找到了文件heart_scale-roc.png。
【讨论】：
但是我没有得到输出应该使用 python 3x 吗？ 也许你把它放在不同的文件夹里。它在您运行脚本的文件夹中创建文件 - 它不必是包含代码或数据文件的文件夹。但是您始终可以在代码中使用完整路径（而不是output_file = path.split(train_file)[1] + '-roc.png'）将文件名分配给 output_file，并且您不必在不同的文件夹中搜索它。
如何将输出重定向到我需要的文件夹
正如我所说 - 你必须在代码中更改 output_file - 代替 output_file = path.split(train_file)[1] + '-roc.png'。放即。 output_file = "/full/path/to/your/folder/output.png"
添加路径我得到以下错误 SyntaxError: 以上是关于Gnuplot 输出设置为“在屏幕上”显示如何更改程序，以便将绘图输出定向到我在下面提供程序的文件夹的主要内容，如果未能解决你的问题，请参考以下文章