Question

Write a program using python that reads from values from a text file and plots them using matplotlib. The input data for each graph is on three lines of the input textfile. The first line contains the x-coordiates of the points of the graph, and the second line contains the y-coordinates of the points of the graph that correspond, in the same order, to the x-coordinates on the first line. The third line in each group of three lines may be blank, in which case the graph will be drawn using all of the defaults. Or that third line may contain the stying information to be used when drawing the graph. This styling info must consist of a string containing from one to four characters giving the line style, the line color, and/or the symbol to be used to mark the points of the graph. Here are the possibilities: Line markers: solid (-), dashed (--), dash-dot (-.), dotted (:) Point markers: . o v ^ < > * + x d D Colors: b g r c m y k w. For example, if three lines of the file contain the following data

1 2 3

2 4 6

--rD

this will produce a straight-line graph determined by the three points shown, with a "large" diamond symbol marking each point and with the points joined by a dashed red line. On the other hand, if the following three lines (the third line is blank) are one group of three lines in the file then the graph will consist of a solid blue line (the defaults) joining the points, and the points themselves will not have any marker.

1 2 3

2 4 6

*Blank line*

The name of the file is read in as the single command-line input, and there is no error-checking required for the existence of the file. Any input file may contain any number of three-line groups of data, so the output of any input file can be any number of graphs.

Answer 1

CODE:

import matplotlib.pyplot as plt
%matplotlib inline

#intializing the variables
marker = ''
linestyle = '-'
color = 'b'
lines = []

#open file
file = open("C:/Users/Win10/Documents/input.txt")

#get the lines
lines = file.readlines()

#remove \n from each line and add ' ' to identify and empty line
lines = list(map(lambda x: x.split('\n')[0]+' ', lines))
#getting the groups of 3
plots = int(len(lines)/3)

#plotting for the number of groups
for i in range(plots):

#populating x and y lists
x = list(map(lambda x: int(x),lines[(3*i)+0].split()))
y = list(map(lambda x: int(x), lines[(3*i)+1].split()))

#if the 3rd line is an empty line in the group
if lines[3*i + 2] == ' ':
plt.figure(figsize = (3,3))
plt.plot(x, y)
plt.show()
else:
#if the length of the 3rd line is 1 that means only the linestyle is provided
if len(lines[3*i+2].replace(' ','')) == 1:
linestyle = lines[(3*i)+2][0]
  
plt.figure(figsize = (3,3))
plt.plot(x, y,linestyle = linestyle)
plt.show()
#if the length of the third line is 2 that means either only the linestyle is given
#or the linestyle and the color is given
elif len(lines[3*i+2].replace(' ','')) == 2:
#if the second character is not a - or . the second char is the color
if lines[(3*i)+2][1] != '-' and lines[(3*i)+2][1] != '.':
linestyle = lines[(3*i)+2][0]
color = lines[(3*i)+2][1]
#else only the linestyle is given
else:
linestyle = lines[(3*i)+2][0:2]
#since b is the default color
color = 'b'
  
plt.figure(figsize = (3,3))
plt.plot(x, y, color = color, linestyle = linestyle)
plt.show()
#if the length is 3 that means either the linestyle, color and marker are given or only
#linestyle and color
elif len(lines[3*i+2].replace(' ','')) == 3:
#similar as above
if lines[(3*i)+2][1] != '-' and lines[(3*i)+2][1] != '.':
linestyle = lines[(3*i)+2][0]
color = lines[(3*i)+2][1]
marker = lines[(3*i)+2][2]
else:
linestyle = lines[(3*i)+2][0:2]
color = lines[(3*i)+2][2]
marker = ''
  
plt.figure(figsize = (3,3))
plt.plot(x, y, color = color ,marker = marker, linestyle = linestyle)
plt.show()
#else all parameters are provided
else:
linestyle = lines[(3*i)+2][0:2]
color = lines[(3*i)+2][2]
marker = lines[(3*i)+2][3]
  
plt.figure(figsize = (3,3))
plt.plot(x, y, color = color ,marker = marker, linestyle = linestyle)
plt.show()
  
#the variables are initialized
x = []
y = []
marker = ''
linestyle = '-'
color = 'b'

______________________________________________________________

CODE IMAGES:

__________________________________________________________________

OUTPUT:

____________________________________________________________________

INPUT FILE:

input.txt

1 2 3
2 4 6
--rD
1 2 3
6 2 9

1 2 3 4 5
2 4 6 12 15
:r
__________________________________________________________________

Feel free to ask any questions in the comments section
Thank You!