資料作りのためのmatplotlib入門(1) 1次元図 ref: https://qiita.com/Bluepost59/items/f2b0a1a8449440de6a1b

file0.f

do i=1,Nx
   write(UNITNUM,*) i,a(i)
end do

file1.txt

1 0.000E00
1 0.628E00
...
10 0.810E01

file2.txt

import numpy as np
import matplotlib as mpl
mpl.use('Agg')
import matplotlib.pyplot as plt

file3.txt

mydata = np.loadtxt('mydata.txt')

file4.txt

[[1,0.0000],
[2,0.628],
...,
10,0.810]]

file5.txt

myax.plot(x,y)

file6.txt

myax.plot(mydata[:,0],mydata[:,1])

file7.txt

import numpy as np
import matplotlib as mpl
matplotlib.use('Agg')
import matplotlib.pyplot as plt

mydata = np.loadtxt('mydata.txt')

myfig = plt.figure()
myax = myfig.add_subplot(1,1,1)

myax.plot(mydata[:,0],mydata[:,1])

myfig.savefig('mydata.png')
myfig.clf()

line_plot.py

import numpy as np
import matplotlib as mpl
matplotlib.use('Agg')
import matplotlib.pyplot as plt

mydata = np.loadtxt('mydata.txt')

myfig = plt.figure()
myax = myfig.add_subplot(1,1,1)

myax.plot(mydata[:,0],mydata[:,1])

myfig.savefig('mydata.png')
myfig.clf()

余計なファイルを削除