scatter function in matplotlib

Question

from numpy import array
import matplotlib
import matplotlib.pyplot as plt
from fileread import file2matrix
datingDataMat,datingLabels = file2matrix('iris_data.txt')
fig = plt.figure()
ax = fig.add_subplot(111)
ax.scatter(datingDataMat[:,1], datingDataMat[:,2],15.0*array(datingLabels), 15.0*array(datingLabels))
plt.show()

This code is displaying error as::

TypeError: unsupported operand type(s) for *: 'float' and 'numpy.ndarray'

According to the author i should be able to generate different colors based on datalabels.

can you post a few lines of your iris_data.txt? so we know what is in your datafile? — usethedeathstar
– usethedeathstar, Commented Oct 25, 2013 at 8:18
40920 8.326976 0.953952 largeDoses 14488 7.153469 1.673904 smallDoses 26052 1.441871 0.805124 didntLike 75136 13.147394 0.428964 didntLike 38344 1.669788 0.134296 didntLike 72993 10.141740 1.032955 didntLike 35948 6.830792 1.213192 largeDoses 42666 13.276369 0.543880 largeDoses 67497 8.631577 0.749278 didntLike 35483 12.273169 1.508053 largeDoses 50242 3.723498 0.831917 didntLike 63275 8.385879 1.669485 didntLike 5569 4.875435 0.728658 smallDoses — Amnesiac
– Amnesiac, Commented Nov 12, 2013 at 6:21

falsetru · Accepted Answer · 2013-10-25 08:21:13Z

3

The array should contains numeric values.

>>> 15.0 * array([1,2])
array([ 15.,  30.])

>>> 15.0 * array(['1','2'])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for *: 'float' and 'numpy.ndarray'

Check the value of datingLabels.

answered Oct 25, 2013 at 8:21

falsetru

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3 Comments

tcp Over a year ago

datinglabels contains strings only.Strange how the author has shown it is working

falsetru Over a year ago

@PavanRavishankar, Try ax.scatter(datingDataMat[:,1], datingDataMat[:,2]).

Amnesiac Over a year ago

@tcp : do one thing, convert all datingLabels inside iris.txt to 0, 1, 2. e.g for didntLike save 0 , for smallDoses save 1 likewise, then it will work

user3163288 · Accepted Answer · 2014-01-05 19:26:14Z

2

I faced the similar problem. Here is what I did . I converted the label to contain numeric values.I am working on python 2.7 , not sure if 3.3 version would have handled it automatically.

newdatLabel = []

for item in datLabel:

if item == 'largeDoses':

    newdatLabel.append(2)

elif item == 'smallDoses':

    newdatLabel.append(1)

elif item == 'didntLike':

    newdatLabel.append(0)

answered Jan 5, 2014 at 19:26

user3163288

212 bronze badges

Comments

J.U · Accepted Answer · 2014-10-17 09:34:26Z

2

Here's another approach

Author provides datingTestSet2.txt

You can download it here (I assume you've done it already)

http://www.manning.com/pharrington/

you can find forth column's values are numeric in this file

but still datingLabels is filled with string values like ['3', '2', '1', .....]

so 15.0*array(datingLabels) doesn't work

To convert the type of an array, use the .astype() method

like 15.0*array(datingLabels).astype(float)

from numpy import array 
import matplotlib
import matplotlib.pyplot as plt
from fileread import file2matrix
datingDataMat,datingLabels = file2matrix('datingDataTest2.txt')
fig = plt.figure()
ax = fig.add_subplot(111)
ax.scatter(datingDataMat[:,1], datingDataMat[:,2],15.0*array(datingLabels).astype(float), 15.0*array(datingLabels).astype(float))
plt.show()

it should work!

edited Oct 17, 2014 at 9:34

answered Oct 17, 2014 at 7:51

J.U

212 bronze badges

1 Comment

Anupam Over a year ago

thanx @J.U. , I think there is one more problem with the kNN.py at line 36, it was trying to convert a string type into int .. so I removed int() conversion then it worked pretty fine ,, well datingDataTest2.txt is correct isn't it??

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