由于sklearn已经把花的名称，进行了格式的转换，分别用0，1，2代替特征Setosa,Versicolour,Virginica.

txt源文件：iris.txt

"Sepal.Length" "Sepal.Width" "Petal.Length" "Petal.Width" "Species"
"1" 5.1 3.5 1.4 0.2 "setosa"
"2" 4.9 3 1.4 0.2 "setosa"
"3" 4.7 3.2 1.3 0.2 "setosa"
"4" 4.6 3.1 1.5 0.2 "setosa"
"5" 5 3.6 1.4 0.2 "setosa"
"6" 5.4 3.9 1.7 0.4 "setosa"
"7" 4.6 3.4 1.4 0.3 "setosa"
"8" 5 3.4 1.5 0.2 "setosa"
"9" 4.4 2.9 1.4 0.2 "setosa"
"10" 4.9 3.1 1.5 0.1 "setosa"
"11" 5.4 3.7 1.5 0.2 "setosa"
"12" 4.8 3.4 1.6 0.2 "setosa"
"13" 4.8 3 1.4 0.1 "setosa"
"14" 4.3 3 1.1 0.1 "setosa"
"15" 5.8 4 1.2 0.2 "setosa"
"16" 5.7 4.4 1.5 0.4 "setosa"
"17" 5.4 3.9 1.3 0.4 "setosa"
"18" 5.1 3.5 1.4 0.3 "setosa"
"19" 5.7 3.8 1.7 0.3 "setosa"
"20" 5.1 3.8 1.5 0.3 "setosa"
"21" 5.4 3.4 1.7 0.2 "setosa"
"22" 5.1 3.7 1.5 0.4 "setosa"
"23" 4.6 3.6 1 0.2 "setosa"
"24" 5.1 3.3 1.7 0.5 "setosa"
"25" 4.8 3.4 1.9 0.2 "setosa"
"26" 5 3 1.6 0.2 "setosa"
"27" 5 3.4 1.6 0.4 "setosa"
"28" 5.2 3.5 1.5 0.2 "setosa"
"29" 5.2 3.4 1.4 0.2 "setosa"
"30" 4.7 3.2 1.6 0.2 "setosa"
"31" 4.8 3.1 1.6 0.2 "setosa"
"32" 5.4 3.4 1.5 0.4 "setosa"
"33" 5.2 4.1 1.5 0.1 "setosa"
"34" 5.5 4.2 1.4 0.2 "setosa"
"35" 4.9 3.1 1.5 0.2 "setosa"
"36" 5 3.2 1.2 0.2 "setosa"
"37" 5.5 3.5 1.3 0.2 "setosa"
"38" 4.9 3.6 1.4 0.1 "setosa"
"39" 4.4 3 1.3 0.2 "setosa"
"40" 5.1 3.4 1.5 0.2 "setosa"
"41" 5 3.5 1.3 0.3 "setosa"
"42" 4.5 2.3 1.3 0.3 "setosa"
"43" 4.4 3.2 1.3 0.2 "setosa"
"44" 5 3.5 1.6 0.6 "setosa"
"45" 5.1 3.8 1.9 0.4 "setosa"
"46" 4.8 3 1.4 0.3 "setosa"
"47" 5.1 3.8 1.6 0.2 "setosa"
"48" 4.6 3.2 1.4 0.2 "setosa"
"49" 5.3 3.7 1.5 0.2 "setosa"
"50" 5 3.3 1.4 0.2 "setosa"
"51" 7 3.2 4.7 1.4 "versicolor"
"52" 6.4 3.2 4.5 1.5 "versicolor"
"53" 6.9 3.1 4.9 1.5 "versicolor"
"54" 5.5 2.3 4 1.3 "versicolor"
"55" 6.5 2.8 4.6 1.5 "versicolor"
"56" 5.7 2.8 4.5 1.3 "versicolor"
"57" 6.3 3.3 4.7 1.6 "versicolor"
"58" 4.9 2.4 3.3 1 "versicolor"
"59" 6.6 2.9 4.6 1.3 "versicolor"
"60" 5.2 2.7 3.9 1.4 "versicolor"
"61" 5 2 3.5 1 "versicolor"
"62" 5.9 3 4.2 1.5 "versicolor"
"63" 6 2.2 4 1 "versicolor"
"64" 6.1 2.9 4.7 1.4 "versicolor"
"65" 5.6 2.9 3.6 1.3 "versicolor"
"66" 6.7 3.1 4.4 1.4 "versicolor"
"67" 5.6 3 4.5 1.5 "versicolor"
"68" 5.8 2.7 4.1 1 "versicolor"
"69" 6.2 2.2 4.5 1.5 "versicolor"
"70" 5.6 2.5 3.9 1.1 "versicolor"
"71" 5.9 3.2 4.8 1.8 "versicolor"
"72" 6.1 2.8 4 1.3 "versicolor"
"73" 6.3 2.5 4.9 1.5 "versicolor"
"74" 6.1 2.8 4.7 1.2 "versicolor"
"75" 6.4 2.9 4.3 1.3 "versicolor"
"76" 6.6 3 4.4 1.4 "versicolor"
"77" 6.8 2.8 4.8 1.4 "versicolor"
"78" 6.7 3 5 1.7 "versicolor"
"79" 6 2.9 4.5 1.5 "versicolor"
"80" 5.7 2.6 3.5 1 "versicolor"
"81" 5.5 2.4 3.8 1.1 "versicolor"
"82" 5.5 2.4 3.7 1 "versicolor"
"83" 5.8 2.7 3.9 1.2 "versicolor"
"84" 6 2.7 5.1 1.6 "versicolor"
"85" 5.4 3 4.5 1.5 "versicolor"
"86" 6 3.4 4.5 1.6 "versicolor"
"87" 6.7 3.1 4.7 1.5 "versicolor"
"88" 6.3 2.3 4.4 1.3 "versicolor"
"89" 5.6 3 4.1 1.3 "versicolor"
"90" 5.5 2.5 4 1.3 "versicolor"
"91" 5.5 2.6 4.4 1.2 "versicolor"
"92" 6.1 3 4.6 1.4 "versicolor"
"93" 5.8 2.6 4 1.2 "versicolor"
"94" 5 2.3 3.3 1 "versicolor"
"95" 5.6 2.7 4.2 1.3 "versicolor"
"96" 5.7 3 4.2 1.2 "versicolor"
"97" 5.7 2.9 4.2 1.3 "versicolor"
"98" 6.2 2.9 4.3 1.3 "versicolor"
"99" 5.1 2.5 3 1.1 "versicolor"
"100" 5.7 2.8 4.1 1.3 "versicolor"
"101" 6.3 3.3 6 2.5 "virginica"
"102" 5.8 2.7 5.1 1.9 "virginica"
"103" 7.1 3 5.9 2.1 "virginica"
"104" 6.3 2.9 5.6 1.8 "virginica"
"105" 6.5 3 5.8 2.2 "virginica"
"106" 7.6 3 6.6 2.1 "virginica"
"107" 4.9 2.5 4.5 1.7 "virginica"
"108" 7.3 2.9 6.3 1.8 "virginica"
"109" 6.7 2.5 5.8 1.8 "virginica"
"110" 7.2 3.6 6.1 2.5 "virginica"
"111" 6.5 3.2 5.1 2 "virginica"
"112" 6.4 2.7 5.3 1.9 "virginica"
"113" 6.8 3 5.5 2.1 "virginica"
"114" 5.7 2.5 5 2 "virginica"
"115" 5.8 2.8 5.1 2.4 "virginica"
"116" 6.4 3.2 5.3 2.3 "virginica"
"117" 6.5 3 5.5 1.8 "virginica"
"118" 7.7 3.8 6.7 2.2 "virginica"
"119" 7.7 2.6 6.9 2.3 "virginica"
"120" 6 2.2 5 1.5 "virginica"
"121" 6.9 3.2 5.7 2.3 "virginica"
"122" 5.6 2.8 4.9 2 "virginica"
"123" 7.7 2.8 6.7 2 "virginica"
"124" 6.3 2.7 4.9 1.8 "virginica"
"125" 6.7 3.3 5.7 2.1 "virginica"
"126" 7.2 3.2 6 1.8 "virginica"
"127" 6.2 2.8 4.8 1.8 "virginica"
"128" 6.1 3 4.9 1.8 "virginica"
"129" 6.4 2.8 5.6 2.1 "virginica"
"130" 7.2 3 5.8 1.6 "virginica"
"131" 7.4 2.8 6.1 1.9 "virginica"
"132" 7.9 3.8 6.4 2 "virginica"
"133" 6.4 2.8 5.6 2.2 "virginica"
"134" 6.3 2.8 5.1 1.5 "virginica"
"135" 6.1 2.6 5.6 1.4 "virginica"
"136" 7.7 3 6.1 2.3 "virginica"
"137" 6.3 3.4 5.6 2.4 "virginica"
"138" 6.4 3.1 5.5 1.8 "virginica"
"139" 6 3 4.8 1.8 "virginica"
"140" 6.9 3.1 5.4 2.1 "virginica"
"141" 6.7 3.1 5.6 2.4 "virginica"
"142" 6.9 3.1 5.1 2.3 "virginica"
"143" 5.8 2.7 5.1 1.9 "virginica"
"144" 6.8 3.2 5.9 2.3 "virginica"
"145" 6.7 3.3 5.7 2.5 "virginica"
"146" 6.7 3 5.2 2.3 "virginica"
"147" 6.3 2.5 5 1.9 "virginica"
"148" 6.5 3 5.2 2 "virginica"
"149" 6.2 3.4 5.4 2.3 "virginica"
"150" 5.9 3 5.1 1.8 "virginica"

最终三分类效果图

命令行输出结果:

['DESCR', 'data', 'feature_names', 'filename', 'frame', 'target', 'target_names']
.. _iris_dataset:

Iris plants dataset
--------------------

**Data Set Characteristics:**

    :Number of Instances: 150 (50 in each of three classes)
    :Number of Attributes: 4 numeric, predictive attributes and the class
    :Attribute Information:
        - sepal length in cm
        - sepal width in cm
        - petal length in cm
        - petal width in cm
        - class:
                - Iris-Setosa
                - Iris-Versicolour
                - Iris-Virginica
                
    :Summary Statistics:

    ============== ==== ==== ======= ===== ====================
                    Min  Max   Mean    SD   Class Correlation
    ============== ==== ==== ======= ===== ====================
    sepal length:   4.3  7.9   5.84   0.83    0.7826
    sepal width:    2.0  4.4   3.05   0.43   -0.4194
    petal length:   1.0  6.9   3.76   1.76    0.9490  (high!)
    petal width:    0.1  2.5   1.20   0.76    0.9565  (high!)
    ============== ==== ==== ======= ===== ====================

    :Missing Attribute Values: None
    :Class Distribution: 33.3% for each of 3 classes.
    :Creator: R.A. Fisher
    :Donor: Michael Marshall (MARSHALL%PLU@io.arc.nasa.gov)
    :Date: July, 1988

The famous Iris database, first used by Sir R.A. Fisher. The dataset is taken
from Fisher's paper. Note that it's the same as in R, but not as in the UCI
Machine Learning Repository, which has two wrong data points.

This is perhaps the best known database to be found in the
pattern recognition literature.  Fisher's paper is a classic in the field and
is referenced frequently to this day.  (See Duda & Hart, for example.)  The
data set contains 3 classes of 50 instances each, where each class refers to a
type of iris plant.  One class is linearly separable from the other 2; the
latter are NOT linearly separable from each other.

.. topic:: References

   - Fisher, R.A. "The use of multiple measurements in taxonomic problems"
     Annual Eugenics, 7, Part II, 179-188 (1936); also in "Contributions to
     Mathematical Statistics" (John Wiley, NY, 1950).
   - Duda, R.O., & Hart, P.E. (1973) Pattern Classification and Scene Analysis.
     (Q327.D83) John Wiley & Sons.  ISBN 0-471-22361-1.  See page 218.
   - Dasarathy, B.V. (1980) "Nosing Around the Neighborhood: A New System
     Structure and Classification Rule for Recognition in Partially Exposed
     Environments".  IEEE Transactions on Pattern Analysis and Machine
     Intelligence, Vol. PAMI-2, No. 1, 67-71.
   - Gates, G.W. (1972) "The Reduced Nearest Neighbor Rule".  IEEE Transactions
     on Information Theory, May 1972, 431-433.
   - See also: 1988 MLC Proceedings, 54-64.  Cheeseman et al"s AUTOCLASS II
     conceptual clustering system finds 3 classes in the data.
   - Many, many more ...

Process finished with exit code 0

同理，更多参考资料:
：缺少属性值：无
：类型分布：3个班级各占33.3%。
：创建者：R.A.Fisher
：捐赠者：迈克尔·马歇尔
：日期：1988年7月
著名的Iris数据库，首先由R.A.Fisher爵士使用。获取数据集
从费舍尔的报纸上。请注意，它与R中的相同，但与UCI中的不同
机器学习库，它有两个错误的数据点。
这也许是世界上最著名的数据库
模式识别文献。费舍尔的论文是这一领域的经典之作
经常提到今天。（例如，见杜达和哈特）
数据集包含3个类，每个类有50个实例，其中每个类引用一个
鸢尾属植物的一种。一类与另两类是线性可分的；另一类是线性可分的
后者不是线性可分离的。
… 主题：：参考文献
-Fisher，R.A.“分类问题中多重测量的使用”
年度优生学，7，第二部分，179-188（1936年）；也在“对
数理统计”（纽约州约翰威利，1950年）。
-Duda，R.O.，&Hart，P.E.（1973）模式分类和场景分析。
（Q327.D83）约翰威利父子公司。国际标准书号0-471-22361-1。见第218页。
-Dasarathy，B.V.（1980），“邻里之间的窥探：一种新的系统
部分暴露区域识别的结构与分类规则
环境”。模式分析与机器翻译
情报，第PAMI-2卷，第1期，67-71页。
-Gates，G.W.（1972）“约化最近邻规则”。IEEE交易
信息论，1972年5月，431-433。
-另见：1988年MLC诉讼，第54-64页。Cheeseman等人的第二类汽车
概念聚类系统在数据中发现了3个类。

已经基本上快标准化啦。
源码附上:

#!/usr/bin/env python 
# -*- coding:utf-8 -*-
# Author's_name_is_NIKOLA_SS
#参考来源:https://www.cnblogs.com/Belter/p/8831216.html

from sklearn.datasets import load_iris
data = load_iris()
print(dir(data))  # 查看data所具有的属性或方法
print(data.DESCR)  # 查看数据集的简介

import pandas as pd
#直接读到pandas的数据框中
pd.DataFrame(data=data.data, columns=data.feature_names)

import matplotlib.pyplot as plt
plt.style.use('ggplot')

X = data.data  # 只包括样本的特征，150x4
y = data.target  # 样本的类型，[0, 1, 2]
features = data.feature_names  # 4个特征的名称
targets = data.target_names  # 3类鸢尾花的名称，跟y中的3个数字对应

plt.figure(figsize=(10, 4))
plt.plot(X[:, 2][y==0], X[:, 3][y==0], 'bs', label=targets[0])
plt.plot(X[:, 2][y==1], X[:, 3][y==1], 'kx', label=targets[1])
plt.plot(X[:, 2][y==2], X[:, 3][y==2], 'ro', label=targets[2])
plt.xlabel(features[2])
plt.ylabel(features[3])
plt.title('Iris Data Set')
plt.legend()
plt.savefig('Iris Data Set.png', dpi=200)
plt.show()