Python plot_data-CodePudding

It first generates some data in a csv file format and the plots it using the plot_data method.

How to solve the bug?

import csv
import matplotlib.pyplot as plt

f = open("data_file.csv", "w")
w = csv.writer(f)
_ = w.writerow(["precision", "recall"])
w.writerows([[0.013,0.951],
             [0.376,0.851],
             [0.441,0.839],
             [0.570,0.758],
             [0.635,0.674],
             [0.721,0.604],
             [0.837,0.531],
             [0.860,0.453],
             [0.962,0.348],
             [0.982,0.273],
             [1.0,0.0]])
f.close()

matplotlib.pyplot.show('data_file.csv')

I am a student, learning Python, how should I plot the data? thank you

CodePudding user response：

You can try this also to display plot

import matplotlib.pyplot as plt
import csv

x = []
y = []

with open('data_file.csv','r') as csvfile:
    plots = csv.reader(csvfile, delimiter = ',')
    
    for row in plots:
        x.append(row[0])
        y.append(row[1])

plt.bar(x, y, color = 'g', width = 0.72, label = "recall")
plt.xlabel('precision')
plt.ylabel('recall')
plt.title('Title')
plt.legend()
plt.show()

import matplotlib.pyplot as plt
import csv

x = []
y = []

with open('data_file.csv','r') as csvfile:
    lines = csv.reader(csvfile, delimiter=',')
    for row in lines:
        x.append(row[0])
        y.append(row[1])

plt.plot(x, y, color = 'g', linestyle = 'dashed',
        marker = 'o',label = "precision")

plt.xticks(rotation = 25)
plt.xlabel('precision')
plt.ylabel('recall')
plt.title('Title', fontsize = 20)
plt.grid()
plt.legend()
plt.show()

CodePudding user response：

So the thing is you have to call plt.plot() before with the data, and then call plt.show() You could do something like:

import csv
import matplotlib.pyplot as plt

f = open("data_file.csv", "w")
w = csv.writer(f)
_ = w.writerow(["precision", "recall"])
rows = [[0.013,0.951],[0.376,0.851],[0.441,0.839],[0.570,0.758],[0.635,0.674],[0.721,0.604],[0.837,0.531],[0.860,0.453],[0.962,0.348],[0.982,0.273],[1.0,0.0]]
precision = [row[0] for row in rows]
recall = [row[1] for row in rows]
w.writerows(rows)
f.close()
plt.plot(precision, recall)
plt.show()

Above you have your data in rows, and your two variables divided in precision and recall. So now you can call plt.plot(precision, recall) and then plt.show

CodePudding user response：

Ideally, your code should have thrown a NameError at the last line, saying 'matplotlib' is not defined. Since you have already imported matplotlib.pyplot as plt, use plt as a reference later in the code, instead of calling matplotlib.pyplot again and again.

You cannot pass a CSV file directly into the plt.show() function as an argument.

I suggest you use Pandas package to create a dataframe out of your CSV file and plot the values like in the below code:

import csv
import matplotlib.pyplot as plt
import pandas as pd

f = open("data_file.csv", "w")
w = csv.writer(f)
_ = w.writerow(["precision", "recall"])
w.writerows([[0.013,0.951],
             [0.376,0.851],
             [0.441,0.839],
             [0.570,0.758],
             [0.635,0.674],
             [0.721,0.604],
             [0.837,0.531],
             [0.860,0.453],
             [0.962,0.348],
             [0.982,0.273],
             [1.0,0.0]])
f.close()

Dataframe = pd.read_csv('data_file.csv')

plt.plot(Dataframe.precision, Dataframe.recall)
plt.show()

You can check more about Pandas documentation here and matplot documentation here