使用matplotlib进行散点图

Question

when I try to use matplotlib to plot the code i see an empty figure with no plots on it. I am attaching the code and the blank figure. Please let me know as to what I am missing. Thanks!

empty window with no plot

from datetime import datetime
start_time = datetime.now()
print(start_time)

import pandas as pd
import numpy as np

file1 = 'fn_data.csv'
import matplotlib.pyplot as plt
#import pylab

# Read the .txt file into a dataframe
data = pd.read_csv(file1, encoding = "ISO-8859-1", header=0, delimiter=',')
rating=data.iloc[:,0]
chef=data.iloc[:,3]
print(rating)

mydict={}
i = 0
for item in chef:
    if(i>0 and item in mydict):
        continue
    else:
       i = i+1
       mydict[item] = i

chef_codes=[]
for item in chef:
    chef_codes.append(mydict[item])

print(chef_codes)
chef_codes_new=np.array(chef_codes)
rating_new=np.array(rating)
print(type(chef_codes_new),type(rating_new))
print(np.max(chef_codes_new),np.max(rating_new))
plt.plot(kind='scatter',x=chef_codes_new,y=rating_new, marker='o', ms = 10, alpha=1, color='b')
plt.axis([0, 1000, 0, 5])
plt.show()
plt.savefig("fig1.png")


end_time = datetime.now()
print(end_time)

Answer 1

def scatterPlot(X,Y):
    ids= ['green' if y == 0 else 'red' for y in Y]
    plt.scatter(X[:,0], X[:,1], color=ids)
    plt.title("Scatter Plot")
    return

scatterPlot(x,y)

Its only an example of scatter plot hope it might help you out from your problem.

Answer 2

If plt.scatter works, plt.plot will work as well. The problem is that you have mixed the syntax of pandas.DataFrame.plot with the command of pyplot.plot .

So, instead of

plt.plot(kind='scatter',x=chef_codes_new,y=rating_new, marker='o', ms = 10, alpha=1, color='b')

you need

plt.plot(chef_codes_new,rating_new, marker='o', ms = 10, alpha=1, color='b')

The syntax is plt.plot(x,y, *args, **kwargs) and you cannot use kind="scatter" in a pyplot plot. If you want a scatter plot, use plt.scatter .