大作业
- 导入数据
- 2. 求出鸢尾属植物萼片长度的平均值、中位数和标准差(第1列,sepallength)
- 3.创建一种标准化形式的鸢尾属植物萼片长度,其值正好介于0和1之间,这样最小值为0,最大值为1(第1列,sepallength)。
- 4. 找到鸢尾属植物萼片长度的第5和第95百分位数(第1列,sepallength)。
- 5. 把iris_data数据集中的20个随机位置修改为np.nan值。
- 6. 在iris_data的sepallength中查找缺失值的个数和位置(第1列)。
- 7. 筛选具有 sepallength(第1列)< 5.0 并且 petallength(第3列)> 1.5 的 iris_data行。
- 选择没有任何 nan 值的 iris_data行。
- 9. 计算 iris_data 中sepalLength(第1列)和petalLength(第3列)之间的相关系数。
- 10. 找出iris_data是否有任何缺失值。
- 11. 在numpy数组中将所有出现的nan替换为0。
- 12. 找出鸢尾属植物物种中的唯一值和唯一值出现的数量。
- -'medium';'>=5--->-'large'。">13. 将 iris_data 的花瓣长度(第3列)以形成分类变量的形式显示。定义:Less than 3 -->'small';3-5 --> 'medium';'>=5 --> 'large'。
- 14. 在 iris_data 中创建一个新列,其中 volume 是 (pi x petallength x sepallength ^ 2)/ 3 。
- 15. 随机抽鸢尾属植物的种类,使得Iris-setosa的数量是Iris-versicolor和Iris-virginica数量的两倍.
- 16. 根据 sepallength 列对数据集进行排序。
- 17. 在鸢尾属植物数据集中找到最常见的花瓣长度值(第3列)。
- 18. 在鸢尾花数据集的 petalwidth(第4列)中查找第一次出现的值大于1.0的位置。
导入数据
import numpy as np
import pandas as pd
from sklearn.datasets import load_iris # 导入数据集
iris = load_iris() # 载入数据
X= iris.data
y = iris.target
target_dict = {
0:'Iris-setosa',1:'Iris-versicolor',2:'Iris-virginica'}
def target(entry):
if entry in target_dict:
return target_dict[entry]
else:
return entry
target_1 = np.vectorize(target)
y = target_1(y)
y
array(['Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-setosa', 'Iris-setosa',
'Iris-setosa', 'Iris-setosa', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-versicolor', 'Iris-versicolor', 'Iris-versicolor',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica', 'Iris-virginica',
'Iris-virginica', 'Iris-virginica'], dtype='<U15')
iris_data = np.c_[X, y]
# iris_col = np.array(['sepallength', 'sepalwidth', 'petalength', 'patalwidth', 'species'])
# iris_data = np.insert(iris_data, 0, values = iris_col, axis = 0)
iris_data
array([['5.1', '3.5', '1.4', '0.2', 'Iris-setosa'],
['4.9', '3.0', '1.4', '0.2', 'Iris-setosa'],
['4.7', '3.2', '1.3', '0.2', 'Iris-setosa'],
['4.6', '3.1', '1.5', '0.2', 'Iris-setosa'],
['5.0', '3.6', '1.4', '0.2', 'Iris-setosa'],
['5.4', '3.9', '1.7', '0.4', 'Iris-setosa'],
['4.6', '3.4', '1.4', '0.3', 'Iris-setosa'],
['5.0', '3.4', '1.5', '0.2', 'Iris-setosa'],
['4.4', '2.9', '1.4', '0.2', 'Iris-setosa'],
['4.9', '3.1', '1.5', '0.1', 'Iris-setosa'],
['5.4', '3.7', '1.5', '0.2', 'Iris-setosa'],
['4.8', '3.4', '1.6', '0.2', 'Iris-setosa'],
['4.8', '3.0', '1.4', '0.1', 'Iris-setosa'],
['4.3', '3.0', '1.1', '0.1', 'Iris-setosa'],
['5.8', '4.0', '1.2', '0.2', 'Iris-setosa'],
['5.7', '4.4', '1.5', '0.4', 'Iris-setosa'],
['5.4', '3.9', '1.3', '0.4', 'Iris-setosa'],
['5.1', '3.5', '1.4', '0.3', 'Iris-setosa'],
['5.7', '3.8', '1.7', '0.3', 'Iris-setosa'],
['5.1', '3.8', '1.5', '0.3', 'Iris-setosa'],
['5.4', '3.4', '1.7', '0.2', 'Iris-setosa'],
['5.1', '3.7', '1.5', '0.4', 'Iris-setosa'],
['4.6', '3.6', '1.0', '0.2', 'Iris-setosa'],
['5.1', '3.3', '1.7', '0.5', 'Iris-setosa'],
['4.8', '3.4', '1.9', '0.2', 'Iris-setosa'],
['5.0', '3.0', '1.6', '0.2', 'Iris-setosa'],
['5.0', '3.4', '1.6', '0.4', 'Iris-setosa'],
['5.2', '3.5', '1.5', '0.2', 'Iris-setosa'],
['5.2', '3.4', '1.4', '0.2', 'Iris-setosa'],
['4.7', '3.2', '1.6', '0.2', 'Iris-setosa'],
['4.8', '3.1', '1.6', '0.2', 'Iris-setosa'],
['5.4', '3.4', '1.5', '0.4', 'Iris-setosa'],
['5.2', '4.1', '1.5', '0.1', 'Iris-setosa'],
['5.5', '4.2', '1.4', '0.2', 'Iris-setosa'],
['4.9', '3.1', '1.5', '0.2', 'Iris-setosa'],
['5.0', '3.2', '1.2', '0.2', 'Iris-setosa'],
['5.5', '3.5', '1.3', '0.2', 'Iris-setosa'],
['4.9', '3.6', '1.4', '0.1', 'Iris-setosa'],
['4.4', '3.0', '1.3', '0.2', 'Iris-setosa'],
['5.1', '3.4', '1.5', '0.2', 'Iris-setosa'],
['5.0', '3.5', '1.3', '0.3', 'Iris-setosa'],
['4.5', '2.3', '1.3', '0.3', 'Iris-setosa'],
['4.4', '3.2', '1.3', '0.2', 'Iris-setosa'],
['5.0', '3.5', '1.6', '0.6', 'Iris-setosa'],
['5.1', '3.8', '1.9', '0.4', 'Iris-setosa'],
['4.8', '3.0', '1.4', '0.3', 'Iris-setosa'],
['5.1', '3.8', '1.6', '0.2', 'Iris-setosa'],
['4.6', '3.2', '1.4', '0.2', 'Iris-setosa'],
['5.3', '3.7', '1.5', '0.2', 'Iris-setosa'],
['5.0', '3.3', '1.4', '0.2', 'Iris-setosa'],
['7.0', '3.2', '4.7', '1.4', 'Iris-versicolor'],
['6.4', '3.2', '4.5', '1.5', 'Iris-versicolor'],
['6.9', '3.1', '4.9', '1.5', 'Iris-versicolor'],
['5.5', '2.3', '4.0', '1.3', 'Iris-versicolor'],
['6.5', '2.8', '4.6', '1.5', 'Iris-versicolor'],
['5.7', '2.8', '4.5', '1.3', 'Iris-versicolor'],
['6.3', '3.3', '4.7', '1.6', 'Iris-versicolor'],
['4.9', '2.4', '3.3', '1.0', 'Iris-versicolor'],
['6.6', '2.9', '4.6', '1.3', 'Iris-versicolor'],
['5.2', '2.7', '3.9', '1.4', 'Iris-versicolor'],
['5.0', '2.0', '3.5', '1.0', 'Iris-versicolor'],
['5.9', '3.0', '4.2', '1.5', 'Iris-versicolor'],
['6.0', '2.2', '4.0', '1.0', 'Iris-versicolor'],
['6.1', '2.9', '4.7', '1.4', 'Iris-versicolor'],
['5.6', '2.9', '3.6', '1.3', 'Iris-versicolor'],
['6.7', '3.1', '4.4', '1.4', 'Iris-versicolor'],
['5.6', '3.0', '4.5', '1.5', 'Iris-versicolor'],
['5.8', '2.7', '4.1', '1.0', 'Iris-versicolor'],
['6.2', '2.2', '4.5', '1.5', 'Iris-versicolor'],
['5.6', '2.5', '3.9', '1.1', 'Iris-versicolor'],
['5.9', '3.2', '4.8', '1.8', 'Iris-versicolor'],
['6.1', '2.8', '4.0', '1.3', 'Iris-versicolor'],
['6.3', '2.5', '4.9', '1.5', 'Iris-versicolor'],
['6.1', '2.8', '4.7', '1.2', 'Iris-versicolor'],
['6.4', '2.9', '4.3', '1.3', 'Iris-versicolor'],
['6.6', '3.0', '4.4', '1.4', 'Iris-versicolor'],
['6.8', '2.8', '4.8', '1.4', 'Iris-versicolor'],
['6.7', '3.0', '5.0', '1.7', 'Iris-versicolor'],
['6.0', '2.9', '4.5', '1.5', 'Iris-versicolor'],
['5.7', '2.6', '3.5', '1.0', 'Iris-versicolor'],
['5.5', '2.4', '3.8', '1.1', 'Iris-versicolor'],
['5.5', '2.4', '3.7', '1.0', 'Iris-versicolor'],
['5.8', '2.7', '3.9', '1.2', 'Iris-versicolor'],
['6.0', '2.7', '5.1', '1.6', 'Iris-versicolor'],
['5.4', '3.0', '4.5', '1.5', 'Iris-versicolor'],
['6.0', '3.4', '4.5', '1.6', 'Iris-versicolor'],
['6.7', '3.1', '4.7', '1.5', 'Iris-versicolor'],
['6.3', '2.3', '4.4', '1.3', 'Iris-versicolor'],
['5.6', '3.0', '4.1', '1.3', 'Iris-versicolor'],
['5.5', '2.5', '4.0', '1.3', 'Iris-versicolor'],
['5.5', '2.6', '4.4', '1.2', 'Iris-versicolor'],
['6.1', '3.0', '4.6', '1.4', 'Iris-versicolor'],
['5.8', '2.6', '4.0', '1.2', 'Iris-versicolor'],
['5.0', '2.3', '3.3', '1.0', 'Iris-versicolor'],
['5.6', '2.7', '4.2', '1.3', 'Iris-versicolor'],
['5.7', '3.0', '4.2', '1.2', 'Iris-versicolor'],
['5.7', '2.9', '4.2', '1.3', 'Iris-versicolor'],
['6.2', '2.9', '4.3', '1.3', 'Iris-versicolor'],
['5.1', '2.5', '3.0', '1.1', 'Iris-versicolor'],
['5.7', '2.8', '4.1', '1.3', 'Iris-versicolor'],
['6.3', '3.3', '6.0', '2.5', 'Iris-virginica'],
['5.8', '2.7', '5.1', '1.9', 'Iris-virginica'],
['7.1', '3.0', '5.9', '2.1', 'Iris-virginica'],
['6.3', '2.9', '5.6', '1.8', 'Iris-virginica'],
['6.5', '3.0', '5.8', '2.2', 'Iris-virginica'],
['7.6', '3.0', '6.6', '2.1', 'Iris-virginica'],
['4.9', '2.5', '4.5', '1.7', 'Iris-virginica'],
['7.3', '2.9', '6.3', '1.8', 'Iris-virginica'],
['6.7', '2.5', '5.8', '1.8', 'Iris-virginica'],
['7.2', '3.6', '6.1', '2.5', 'Iris-virginica'],
['6.5', '3.2', '5.1', '2.0', 'Iris-virginica'],
['6.4', '2.7', '5.3', '1.9', 'Iris-virginica'],
['6.8', '3.0', '5.5', '2.1', 'Iris-virginica'],
['5.7', '2.5', '5.0', '2.0', 'Iris-virginica'],
['5.8', '2.8', '5.1', '2.4', 'Iris-virginica'],
['6.4', '3.2', '5.3', '2.3', 'Iris-virginica'],
['6.5', '3.0', '5.5', '1.8', 'Iris-virginica'],
['7.7', '3.8', '6.7', '2.2', 'Iris-virginica'],
['7.7', '2.6', '6.9', '2.3', 'Iris-virginica'],
['6.0', '2.2', '5.0', '1.5', 'Iris-virginica'],
['6.9', '3.2', '5.7', '2.3', 'Iris-virginica'],
['5.6', '2.8', '4.9', '2.0', 'Iris-virginica'],
['7.7', '2.8', '6.7', '2.0', 'Iris-virginica'],
['6.3', '2.7', '4.9', '1.8', 'Iris-virginica'],
['6.7', '3.3', '5.7', '2.1', 'Iris-virginica'],
['7.2', '3.2', '6.0', '1.8', 'Iris-virginica'],
['6.2', '2.8', '4.8', '1.8', 'Iris-virginica'],
['6.1', '3.0', '4.9', '1.8', 'Iris-virginica'],
['6.4', '2.8', '5.6', '2.1', 'Iris-virginica'],
['7.2', '3.0', '5.8', '1.6', 'Iris-virginica'],
['7.4', '2.8', '6.1', '1.9', 'Iris-virginica'],
['7.9', '3.8', '6.4', '2.0', 'Iris-virginica'],
['6.4', '2.8', '5.6', '2.2', 'Iris-virginica'],
['6.3', '2.8', '5.1', '1.5', 'Iris-virginica'],
['6.1', '2.6', '5.6', '1.4', 'Iris-virginica'],
['7.7', '3.0', '6.1', '2.3', 'Iris-virginica'],
['6.3', '3.4', '5.6', '2.4', 'Iris-virginica'],
['6.4', '3.1', '5.5', '1.8', 'Iris-virginica'],
['6.0', '3.0', '4.8', '1.8', 'Iris-virginica'],
['6.9', '3.1', '5.4', '2.1', 'Iris-virginica'],
['6.7', '3.1', '5.6', '2.4', 'Iris-virginica'],
['6.9', '3.1', '5.1', '2.3', 'Iris-virginica'],
['5.8', '2.7', '5.1', '1.9', 'Iris-virginica'],
['6.8', '3.2', '5.9', '2.3', 'Iris-virginica'],
['6.7', '3.3', '5.7', '2.5', 'Iris-virginica'],
['6.7', '3.0', '5.2', '2.3', 'Iris-virginica'],
['6.3', '2.5', '5.0', '1.9', 'Iris-virginica'],
['6.5', '3.0', '5.2', '2.0', 'Iris-virginica'],
['6.2', '3.4', '5.4', '2.3', 'Iris-virginica'],
['5.9', '3.0', '5.1', '1.8', 'Iris-virginica']], dtype='<U32')
outfile = r'.\iris.data'
pd.DataFrame(iris_data).to_csv(outfile)
iris_data = np.loadtxt(outfile, dtype=object, delimiter=',')
iris_data
array([['', '0', '1', '2', '3', '4'],
['0', '5.1', '3.5', '1.4', '0.2', 'Iris-setosa'],
['1', '4.9', '3.0', '1.4', '0.2', 'Iris-setosa'],
['2', '4.7', '3.2', '1.3', '0.2', 'Iris-setosa'],
['3', '4.6', '3.1', '1.5', '0.2', 'Iris-setosa'],
['4', '5.0', '3.6', '1.4', '0.2', 'Iris-setosa'],
['5', '5.4', '3.9', '1.7', '0.4', 'Iris-setosa'],
['6', '4.6', '3.4', '1.4', '0.3', 'Iris-setosa'],
['7', '5.0', '3.4', '1.5', '0.2', 'Iris-setosa'],
['8', '4.4', '2.9', '1.4', '0.2', 'Iris-setosa'],
['9', '4.9', '3.1', '1.5', '0.1', 'Iris-setosa'],
['10', '5.4', '3.7', '1.5', '0.2', 'Iris-setosa'],
['11', '4.8', '3.4', '1.6', '0.2', 'Iris-setosa'],
['12', '4.8', '3.0', '1.4', '0.1', 'Iris-setosa'],
['13', '4.3', '3.0', '1.1', '0.1', 'Iris-setosa'],
['14', '5.8', '4.0', '1.2', '0.2', 'Iris-setosa'],
['15', '5.7', '4.4', '1.5', '0.4', 'Iris-setosa'],
['16', '5.4', '3.9', '1.3', '0.4', 'Iris-setosa'],
['17', '5.1', '3.5', '1.4', '0.3', 'Iris-setosa'],
['18', '5.7', '3.8', '1.7', '0.3', 'Iris-setosa'],
['19', '5.1', '3.8', '1.5', '0.3', 'Iris-setosa'],
['20', '5.4', '3.4', '1.7', '0.2', 'Iris-setosa'],
['21', '5.1', '3.7', '1.5', '0.4', 'Iris-setosa'],
['22', '4.6', '3.6', '1.0', '0.2', 'Iris-setosa'],
['23', '5.1', '3.3', '1.7', '0.5', 'Iris-setosa'],
['24', '4.8', '3.4', '1.9', '0.2', 'Iris-setosa'],
['25', '5.0', '3.0', '1.6', '0.2', 'Iris-setosa'],
['26', '5.0', '3.4', '1.6', '0.4', 'Iris-setosa'],
['27', '5.2', '3.5', '1.5', '0.2', 'Iris-setosa'],
['28', '5.2', '3.4', '1.4', '0.2', 'Iris-setosa'],
['29', '4.7', '3.2', '1.6', '0.2', 'Iris-setosa'],
['30', '4.8', '3.1', '1.6', '0.2', 'Iris-setosa'],
['31', '5.4', '3.4', '1.5', '0.4', 'Iris-setosa'],
['32', '5.2', '4.1', '1.5', '0.1', 'Iris-setosa'],
['33', '5.5', '4.2', '1.4', '0.2', 'Iris-setosa'],
['34', '4.9', '3.1', '1.5', '0.2', 'Iris-setosa'],
['35', '5.0', '3.2', '1.2', '0.2', 'Iris-setosa'],
['36', '5.5', '3.5', '1.3', '0.2', 'Iris-setosa'],
['37', '4.9', '3.6', '1.4', '0.1', 'Iris-setosa'],
['38', '4.4', '3.0', '1.3', '0.2', 'Iris-setosa'],
['39', '5.1', '3.4', '1.5', '0.2', 'Iris-setosa'],
['40', '5.0', '3.5', '1.3', '0.3', 'Iris-setosa'],
['41', '4.5', '2.3', '1.3', '0.3', 'Iris-setosa'],
['42', '4.4', '3.2', '1.3', '0.2', 'Iris-setosa'],
['43', '5.0', '3.5', '1.6', '0.6', 'Iris-setosa'],
['44', '5.1', '3.8', '1.9', '0.4', 'Iris-setosa'],
['45', '4.8', '3.0', '1.4', '0.3', 'Iris-setosa'],
['46', '5.1', '3.8', '1.6', '0.2', 'Iris-setosa'],
['47', '4.6', '3.2', '1.4', '0.2', 'Iris-setosa'],
['48', '5.3', '3.7', '1.5', '0.2', 'Iris-setosa'],
['49', '5.0', '3.3', '1.4', '0.2', 'Iris-setosa'],
['50', '7.0', '3.2', '4.7', '1.4', 'Iris-versicolor'],
['51', '6.4', '3.2', '4.5', '1.5', 'Iris-versicolor'],
['52', '6.9', '3.1', '4.9', '1.5', 'Iris-versicolor'],
['53', '5.5', '2.3', '4.0', '1.3', 'Iris-versicolor'],
['54', '6.5', '2.8', '4.6', '1.5', 'Iris-versicolor'],
['55', '5.7', '2.8', '4.5', '1.3', 'Iris-versicolor'],
['56', '6.3', '3.3', '4.7', '1.6', 'Iris-versicolor'],
['57', '4.9', '2.4', '3.3', '1.0', 'Iris-versicolor'],
['58', '6.6', '2.9', '4.6', '1.3', 'Iris-versicolor'],
['59', '5.2', '2.7', '3.9', '1.4', 'Iris-versicolor'],
['60', '5.0', '2.0', '3.5', '1.0', 'Iris-versicolor'],
['61', '5.9', '3.0', '4.2', '1.5', 'Iris-versicolor'],
['62', '6.0', '2.2', '4.0', '1.0', 'Iris-versicolor'],
['63', '6.1', '2.9', '4.7', '1.4', 'Iris-versicolor'],
['64', '5.6', '2.9', '3.6', '1.3', 'Iris-versicolor'],
['65', '6.7', '3.1', '4.4', '1.4', 'Iris-versicolor'],
['66', '5.6', '3.0', '4.5', '1.5', 'Iris-versicolor'],
['67', '5.8', '2.7', '4.1', '1.0', 'Iris-versicolor'],
['68', '6.2', '2.2', '4.5', '1.5', 'Iris-versicolor'],
['69', '5.6', '2.5', '3.9', '1.1', 'Iris-versicolor'],
['70', '5.9', '3.2', '4.8', '1.8', 'Iris-versicolor'],
['71', '6.1', '2.8', '4.0', '1.3', 'Iris-versicolor'],
['72', '6.3', '2.5', '4.9', '1.5', 'Iris-versicolor'],
['73', '6.1', '2.8', '4.7', '1.2', 'Iris-versicolor'],
['74', '6.4', '2.9', '4.3', '1.3', 'Iris-versicolor'],
['75', '6.6', '3.0', '4.4', '1.4', 'Iris-versicolor'],
['76', '6.8', '2.8', '4.8', '1.4', 'Iris-versicolor'],
['77', '6.7', '3.0', '5.0', '1.7', 'Iris-versicolor'],
['78', '6.0', '2.9', '4.5', '1.5', 'Iris-versicolor'],
['79', '5.7', '2.6', '3.5', '1.0', 'Iris-versicolor'],
['80', '5.5', '2.4', '3.8', '1.1', 'Iris-versicolor'],
['81', '5.5', '2.4', '3.7', '1.0', 'Iris-versicolor'],
['82', '5.8', '2.7', '3.9', '1.2', 'Iris-versicolor'],
['83', '6.0', '2.7', '5.1', '1.6', 'Iris-versicolor'],
['84', '5.4', '3.0', '4.5', '1.5', 'Iris-versicolor'],
['85', '6.0', '3.4', '4.5', '1.6', 'Iris-versicolor'],
['86', '6.7', '3.1', '4.7', '1.5', 'Iris-versicolor'],
['87', '6.3', '2.3', '4.4', '1.3', 'Iris-versicolor'],
['88', '5.6', '3.0', '4.1', '1.3', 'Iris-versicolor'],
['89', '5.5', '2.5', '4.0', '1.3', 'Iris-versicolor'],
['90', '5.5', '2.6', '4.4', '1.2', 'Iris-versicolor'],
['91', '6.1', '3.0', '4.6', '1.4', 'Iris-versicolor'],
['92', '5.8', '2.6', '4.0', '1.2', 'Iris-versicolor'],
['93', '5.0', '2.3', '3.3', '1.0', 'Iris-versicolor'],
['94', '5.6', '2.7', '4.2', '1.3', 'Iris-versicolor'],
['95', '5.7', '3.0', '4.2', '1.2', 'Iris-versicolor'],
['96', '5.7', '2.9', '4.2', '1.3', 'Iris-versicolor'],
['97', '6.2', '2.9', '4.3', '1.3', 'Iris-versicolor'],
['98', '5.1', '2.5', '3.0', '1.1', 'Iris-versicolor'],
['99', '5.7', '2.8', '4.1', '1.3', 'Iris-versicolor'],
['100', '6.3', '3.3', '6.0', '2.5', 'Iris-virginica'],
['101', '5.8', '2.7', '5.1', '1.9', 'Iris-virginica'],
['102', '7.1', '3.0', '5.9', '2.1', 'Iris-virginica'],
['103', '6.3', '2.9', '5.6', '1.8', 'Iris-virginica'],
['104', '6.5', '3.0', '5.8', '2.2', 'Iris-virginica'],
['105', '7.6', '3.0', '6.6', '2.1', 'Iris-virginica'],
['106', '4.9', '2.5', '4.5', '1.7', 'Iris-virginica'],
['107', '7.3', '2.9', '6.3', '1.8', 'Iris-virginica'],
['108', '6.7', '2.5', '5.8', '1.8', 'Iris-virginica'],
['109', '7.2', '3.6', '6.1', '2.5', 'Iris-virginica'],
['110', '6.5', '3.2', '5.1', '2.0', 'Iris-virginica'],
['111', '6.4', '2.7', '5.3', '1.9', 'Iris-virginica'],
['112', '6.8', '3.0', '5.5', '2.1', 'Iris-virginica'],
['113', '5.7', '2.5', '5.0', '2.0', 'Iris-virginica'],
['114', '5.8', '2.8', '5.1', '2.4', 'Iris-virginica'],
['115', '6.4', '3.2', '5.3', '2.3', 'Iris-virginica'],
['116', '6.5', '3.0', '5.5', '1.8', 'Iris-virginica'],
['117', '7.7', '3.8', '6.7', '2.2', 'Iris-virginica'],
['118', '7.7', '2.6', '6.9', '2.3', 'Iris-virginica'],
['119', '6.0', '2.2', '5.0', '1.5', 'Iris-virginica'],
['120', '6.9', '3.2', '5.7', '2.3', 'Iris-virginica'],
['121', '5.6', '2.8', '4.9', '2.0', 'Iris-virginica'],
['122', '7.7', '2.8', '6.7', '2.0', 'Iris-virginica'],
['123', '6.3', '2.7', '4.9', '1.8', 'Iris-virginica'],
['124', '6.7', '3.3', '5.7', '2.1', 'Iris-virginica'],
['125', '7.2', '3.2', '6.0', '1.8', 'Iris-virginica'],
['126', '6.2', '2.8', '4.8', '1.8', 'Iris-virginica'],
['127', '6.1', '3.0', '4.9', '1.8', 'Iris-virginica'],
['128', '6.4', '2.8', '5.6', '2.1', 'Iris-virginica'],
['129', '7.2', '3.0', '5.8', '1.6', 'Iris-virginica'],
['130', '7.4', '2.8', '6.1', '1.9', 'Iris-virginica'],
['131', '7.9', '3.8', '6.4', '2.0', 'Iris-virginica'],
['132', '6.4', '2.8', '5.6', '2.2', 'Iris-virginica'],
['133', '6.3', '2.8', '5.1', '1.5', 'Iris-virginica'],
['134', '6.1', '2.6', '5.6', '1.4', 'Iris-virginica'],
['135', '7.7', '3.0', '6.1', '2.3', 'Iris-virginica'],
['136', '6.3', '3.4', '5.6', '2.4', 'Iris-virginica'],
['137', '6.4', '3.1', '5.5', '1.8', 'Iris-virginica'],
['138', '6.0', '3.0', '4.8', '1.8', 'Iris-virginica'],
['139', '6.9', '3.1', '5.4', '2.1', 'Iris-virginica'],
['140', '6.7', '3.1', '5.6', '2.4', 'Iris-virginica'],
['141', '6.9', '3.1', '5.1', '2.3', 'Iris-virginica'],
['142', '5.8', '2.7', '5.1', '1.9', 'Iris-virginica'],
['143', '6.8', '3.2', '5.9', '2.3', 'Iris-virginica'],
['144', '6.7', '3.3', '5.7', '2.5', 'Iris-virginica'],
['145', '6.7', '3.0', '5.2', '2.3', 'Iris-virginica'],
['146', '6.3', '2.5', '5.0', '1.9', 'Iris-virginica'],
['147', '6.5', '3.0', '5.2', '2.0', 'Iris-virginica'],
['148', '6.2', '3.4', '5.4', '2.3', 'Iris-virginica'],
['149', '5.9', '3.0', '5.1', '1.8', 'Iris-virginica']],
dtype=object)
2. 求出鸢尾属植物萼片长度的平均值、中位数和标准差(第1列,sepallength)
【知识点:统计相关】
- 如何计算numpy数组的均值,中位数,标准差?
sepalLength = np.loadtxt(outfile, dtype = float, delimiter = ',', skiprows=1, usecols = [1])
print(sepalLength)
[5.1 4.9 4.7 4.6 5. 5.4 4.6 5. 4.4 4.9 5.4 4.8 4.8 4.3 5.8 5.7 5.4 5.1
5.7 5.1 5.4 5.1 4.6 5.1 4.8 5. 5. 5.2 5.2 4.7 4.8 5.4 5.2 5.5 4.9 5.
5.5 4.9 4.4 5.1 5. 4.5 4.4 5. 5.1 4.8 5.1 4.6 5.3 5. 7. 6.4 6.9 5.5
6.5 5.7 6.3 4.9 6.6 5.2 5. 5.9 6. 6.1 5.6 6.7 5.6 5.8 6.2 5.6 5.9 6.1
6.3 6.1 6.4 6.6 6.8 6.7 6. 5.7 5.5 5.5 5.8 6. 5.4 6. 6.7 6.3 5.6 5.5
5.5 6.1 5.8 5. 5.6 5.7 5.7 6.2 5.1 5.7 6.3 5.8 7.1 6.3 6.5 7.6 4.9 7.3
6.7 7.2 6.5 6.4 6.8 5.7 5.8 6.4 6.5 7.7 7.7 6. 6.9 5.6 7.7 6.3 6.7 7.2
6.2 6.1 6.4 7.2 7.4 7.9 6.4 6.3 6.1 7.7 6.3 6.4 6. 6.9 6.7 6.9 5.8 6.8
6.7 6.7 6.3 6.5 6.2 5.9]
print(np.mean(sepalLength))
# 5.843333333333334
print(np.median(sepalLength))
# 5.8
print(np.std(sepalLength))
# 0.8253012917851409
5.843333333333334
5.8
0.8253012917851409
3.创建一种标准化形式的鸢尾属植物萼片长度,其值正好介于0和1之间,这样最小值为0,最大值为1(第1列,sepallength)。
【知识点:统计相关】
- 如何标准化数组?
amax = np.amax(sepalLength)
amin = np.min(sepalLength)
x = (sepalLength - amin)/(amax - amin)
print(x[0:10])
[0.22222222 0.16666667 0.11111111 0.08333333 0.19444444 0.30555556
0.08333333 0.19444444 0.02777778 0.16666667]
# 方法二
x = (sepalLength - amin)/np.ptp(sepalLength)
print(x[0:10])
[0.22222222 0.16666667 0.11111111 0.08333333 0.19444444 0.30555556
0.08333333 0.19444444 0.02777778 0.16666667]
4. 找到鸢尾属植物萼片长度的第5和第95百分位数(第1列,sepallength)。
【知识点:统计相关】
- 如何找到numpy数组的百分位数?
x = np.percentile(sepalLength, [5, 95])
print(x)
[4.6 7.255]
5. 把iris_data数据集中的20个随机位置修改为np.nan值。
【知识点:随机抽样】
- 如何在数组中的随机位置修改值?
import numpy as np
iris_data = np.loadtxt(outfile, dtype = object, delimiter=',', skiprows= 1)
iris_data = iris_data [:, 1:]
i, j = iris_data.shape
print (i, j)
150 5
# 方法1
np.random.seed(20200621)
iris_data[np.random.randint(i, size= 20), np.random.randint(j, size = 20)] = np.nan
print(iris_data[0:10])
[['5.1' '3.5' '1.4' '0.2' 'Iris-setosa']
['4.9' '3.0' '1.4' '0.2' 'Iris-setosa']
['4.7' '3.2' '1.3' '0.2' 'Iris-setosa']
['4.6' '3.1' '1.5' '0.2' 'Iris-setosa']
['5.0' '3.6' '1.4' '0.2' 'Iris-setosa']
['5.4' nan '1.7' '0.4' 'Iris-setosa']
['4.6' '3.4' '1.4' '0.3' 'Iris-setosa']
['5.0' '3.4' '1.5' '0.2' 'Iris-setosa']
['4.4' '2.9' '1.4' '0.2' nan]
['4.9' '3.1' '1.5' '0.1' 'Iris-setosa']]
# 方法2
np.random.seed(20200620)
# 参数意思分别 是从a 中以概率P,随机选择3个, p没有指定的时候相当于是一致的分布
a1 = np.random.choice(a=5, size=3, replace=False, p=None)
iris_data[np.random.choice(i, size=20), np.random.choice(j, size=20)] = np.nan
print(iris_data[0:10])
[['5.1' '3.5' nan '0.2' 'Iris-setosa']
['4.9' '3.0' '1.4' '0.2' 'Iris-setosa']
['4.7' '3.2' '1.3' '0.2' 'Iris-setosa']
['4.6' '3.1' '1.5' '0.2' 'Iris-setosa']
['5.0' '3.6' '1.4' nan 'Iris-setosa']
['5.4' nan '1.7' '0.4' 'Iris-setosa']
['4.6' '3.4' '1.4' '0.3' 'Iris-setosa']
['5.0' '3.4' '1.5' '0.2' 'Iris-setosa']
['4.4' '2.9' '1.4' '0.2' nan]
['4.9' '3.1' '1.5' '0.1' 'Iris-setosa']]
6. 在iris_data的sepallength中查找缺失值的个数和位置(第1列)。
【知识点:逻辑函数、搜索】
- 如何在numpy数组中找到缺失值的位置?
import numpy as np
outfile = r'.\iris.data'
iris_data = np.loadtxt(outfile, dtype=float, delimiter=',', skiprows=1, usecols=[0, 1, 2,
3])
i, j = iris_data.shape
np.random.seed(20200621)
iris_data[np.random.randint(i, size=20), np.random.randint(j, size=20)] = np.nan
sepallength = iris_data[:, 0]
sepallength
a = np.isnan(iris_data[:, 0])
print(sum(a)) # 6
print(np.where(a))
# (array([ 26, 44, 55, 63, 90, 115], dtype=int64),)
6
(array([ 26, 44, 55, 63, 90, 115], dtype=int64),)
7. 筛选具有 sepallength(第1列)< 5.0 并且 petallength(第3列)> 1.5 的 iris_data行。
【知识点:搜索】
- 如何根据两个或多个条件筛选numpy数组?
import numpy as np
outfile = r'.\iris.data'
iris_data = np.loadtxt(outfile, dtype='float', delimiter=',', skiprows=1, usecols=[1, 2, 3, 4])
sepallength = iris_data[:, 0]
petallength = iris_data[:, 2]
index = np.where(np.logical_and(petallength > 1.5, sepallength < 5.0))
print(iris_data[index])
[[4.8 3.4 1.6 0.2]
[4.8 3.4 1.9 0.2]
[4.7 3.2 1.6 0.2]
[4.8 3.1 1.6 0.2]
[4.9 2.4 3.3 1. ]
[4.9 2.5 4.5 1.7]]
选择没有任何 nan 值的 iris_data行。
【知识点:逻辑函数、搜索】
- 如何从numpy数组中删除包含缺失值的行?
import numpy as np
outfil = r'./iris.data'
iris_data = np.loadtxt(outfile, dtype=float, delimiter=',', skiprows=1, usecols=[1, 2, 3, 4])
i, j = iris_data.shape
np.random.seed(20200621)
iris_data[np.random.randint(i, size= 20), np.random.randint(j, size = 20)] = np.nan
b = np.isnan(iris_data)
x = iris_data[np.sum(b, axis=1) == 0]
print(x[0:10])
[[5.1 3.5 1.4 0.2]
[4.9 3. 1.4 0.2]
[4.7 3.2 1.3 0.2]
[4.6 3.1 1.5 0.2]
[5. 3.6 1.4 0.2]
[4.6 3.4 1.4 0.3]
[5. 3.4 1.5 0.2]
[4.9 3.1 1.5 0.1]
[5.4 3.7 1.5 0.2]
[4.8 3.4 1.6 0.2]]
9. 计算 iris_data 中sepalLength(第1列)和petalLength(第3列)之间的相关系数。
【知识点:统计相关】
- 如何计算numpy数组两列之间的相关系数?
iris_data = np.loadtxt(outfile, dtype = 'float', delimiter = ',', skiprows = 1, usecols = [1, 2, 3, 4])
sepalLength = iris_data[:, 0]
petalLength = iris_data[:, 2]
x = np.corrcoef(sepalLength,petalLength )
x
array([[1. , 0.87175378],
[0.87175378, 1. ]])
10. 找出iris_data是否有任何缺失值。
- 找出iris_data是否有任何缺失值。
- 如何查找给定数组是否具有空值?
x = np.isnan(iris_data)
x
print(np.any(x)) # False
False
11. 在numpy数组中将所有出现的nan替换为0。
【知识点:逻辑函数】
- 如何在numpy数组中用0替换所有缺失值?
import numpy as np
outfile = r'.\iris.data'
iris_data = np.loadtxt(outfile, dtype=float, delimiter=',', skiprows=1, usecols=[1, 2, 3,
4])
i, j = iris_data.shape
np.random.seed(20200621)
iris_data[np.random.randint(i, size=20), np.random.randint(j, size=20)] = np.nan
iris_data[np.isnan(iris_data)] = 0
print(iris_data[0:10])
[[5.1 3.5 1.4 0.2]
[4.9 3. 1.4 0.2]
[4.7 3.2 1.3 0.2]
[4.6 3.1 1.5 0.2]
[5. 3.6 1.4 0.2]
[5.4 0. 1.7 0.4]
[4.6 3.4 1.4 0.3]
[5. 3.4 1.5 0.2]
[4.4 2.9 0. 0.2]
[4.9 3.1 1.5 0.1]]
12. 找出鸢尾属植物物种中的唯一值和唯一值出现的数量。
【知识点:数组操作】
- 如何在numpy数组中查找唯一值的计数?
import numpy as np
outfile = r'.\iris.data'
iris_data = np.loadtxt(outfile, dtype=object, delimiter=',', skiprows=1, usecols=[5])
x = np.unique(iris_data, return_counts= True)
print(x)
# (array(['Iris‐setosa', 'Iris‐versicolor', 'Iris‐virginica'], dtype=object), array([50,
# 50, 50], dtype=int64))
(array(['Iris-setosa', 'Iris-versicolor', 'Iris-virginica'], dtype=object), array([50, 50, 50], dtype=int64))
13. 将 iris_data 的花瓣长度(第3列)以形成分类变量的形式显示。定义:Less than 3 -->‘small’;3-5 --> ‘medium’;’>=5 --> ‘large’。
【知识点:统计相关】
- 如何将数字转换为分类(文本)数组?
import numpy as np
outfile = r'.\iris.data'
iris_data = np.loadtxt(outfile, dtype=float, delimiter=',', skiprows=1, usecols=[1, 2, 3,
4])
petal_length_bin = np.digitize(iris_data[:, 3], [0, 3, 5, 10])
label_map = {
1: 'small', 2: 'medium', 3: 'large', 4: np.nan}
petal_length_cat = [label_map[x] for x in petal_length_bin]
print(petal_length_cat[0:10])
# ['small', 'small', 'small', 'small', 'small', 'small', 'small', 'small', 'small',
#'small']
['small', 'small', 'small', 'small', 'small', 'small', 'small', 'small', 'small', 'small']
14. 在 iris_data 中创建一个新列,其中 volume 是 (pi x petallength x sepallength ^ 2)/ 3 。
【知识点:数组操作】
- 如何从numpy数组的现有列创建新列?
import numpy as np
outfile = r'.\iris.data'
iris_data = np.loadtxt(outfile, dtype=object, delimiter=',', skiprows=1)
sepalLength = iris_data[:, 1].astype(float)
petalLength = iris_data[:, 3].astype(float)
volume = (np.pi * petalLength * sepalLength ** 2) / 3
volume = volume[:, np.newaxis]
# 这样改变维度的作用往往是将一维的数据转变成一个矩阵,与代码后面的权重矩阵进行相乘,
# 否则单单的数据是不能呢这样相乘的哦。这样改变维度的作用往往是将一维的数据转变成一个矩阵,
# 与代码后面的权重矩阵进行相乘, 否则单单的数据是不能呢这样相乘的哦。
iris_data = np.concatenate([iris_data, volume], axis=1)
print(iris_data[0:10])
# [['5.1' '3.5' '1.4' '0.2' 'Iris‐setosa' 38.13265162927291]
# ['4.9' '3.0' '1.4' '0.2' 'Iris‐setosa' 35.200498485922445]
# ['4.7' '3.2' '1.3' '0.2' 'Iris‐setosa' 30.0723720777127]
# ['4.6' '3.1' '1.5' '0.2' 'Iris‐setosa' 33.238050274980004]
# ['5.0' '3.6' '1.4' '0.2' 'Iris‐setosa' 36.65191429188092]
[['0' '5.1' '3.5' '1.4' '0.2' 'Iris-setosa' 38.13265162927291]
['1' '4.9' '3.0' '1.4' '0.2' 'Iris-setosa' 35.200498485922445]
['2' '4.7' '3.2' '1.3' '0.2' 'Iris-setosa' 30.0723720777127]
['3' '4.6' '3.1' '1.5' '0.2' 'Iris-setosa' 33.238050274980004]
['4' '5.0' '3.6' '1.4' '0.2' 'Iris-setosa' 36.65191429188092]
['5' '5.4' '3.9' '1.7' '0.4' 'Iris-setosa' 51.911677007917746]
['6' '4.6' '3.4' '1.4' '0.3' 'Iris-setosa' 31.022180256648003]
['7' '5.0' '3.4' '1.5' '0.2' 'Iris-setosa' 39.269908169872416]
['8' '4.4' '2.9' '1.4' '0.2' 'Iris-setosa' 28.38324242763259]
['9' '4.9' '3.1' '1.5' '0.1' 'Iris-setosa' 37.714819806345474]]
15. 随机抽鸢尾属植物的种类,使得Iris-setosa的数量是Iris-versicolor和Iris-virginica数量的两倍.
【知识点:随机抽样】
- 如何在numpy中进行概率抽样?
import numpy as np
species = np.array(['Iris‐setosa', 'Iris‐versicolor', 'Iris‐virginica'])
species_out = np.random.choice(species,10000, p = [0.5, 0.25, 0.25])
print(np.unique(species_out, return_counts = True))
(array(['Iris‐setosa', 'Iris‐versicolor', 'Iris‐virginica'], dtype='<U15'), array([5057, 2445, 2498], dtype=int64))
16. 根据 sepallength 列对数据集进行排序。
【知识点:排序】
- 如何按列对2D数组进行排序?
iris_data = np.loadtxt(outfile, dtype = object, delimiter = ',', skiprows = 1)
sepalLength = iris_data[:, 1]
index = np.argsort(sepalLength)
print(iris_data[index][0:10])
[['13' '4.3' '3.0' '1.1' '0.1' 'Iris-setosa']
['42' '4.4' '3.2' '1.3' '0.2' 'Iris-setosa']
['38' '4.4' '3.0' '1.3' '0.2' 'Iris-setosa']
['8' '4.4' '2.9' '1.4' '0.2' 'Iris-setosa']
['41' '4.5' '2.3' '1.3' '0.3' 'Iris-setosa']
['22' '4.6' '3.6' '1.0' '0.2' 'Iris-setosa']
['3' '4.6' '3.1' '1.5' '0.2' 'Iris-setosa']
['6' '4.6' '3.4' '1.4' '0.3' 'Iris-setosa']
['47' '4.6' '3.2' '1.4' '0.2' 'Iris-setosa']
['2' '4.7' '3.2' '1.3' '0.2' 'Iris-setosa']]
17. 在鸢尾属植物数据集中找到最常见的花瓣长度值(第3列)。
【知识点:数组操作】
- 如何在numpy数组中找出出现次数最多的值?
iris_data = np.loadtxt(outfile, dtype = object, delimiter = ',', skiprows = 1)
petalLength = iris_data[:, 3]
vals, counts = np.unique(petalLength, return_counts=True)
print(vals[np.argmax(counts)]) # 1.5 #取出counts中元素最大值所对应的索引,
print(np.amax(counts)) # 14
1.4
13
18. 在鸢尾花数据集的 petalwidth(第4列)中查找第一次出现的值大于1.0的位置。
【知识点:搜索】
- 如何找到第一次出现大于给定值的位置?
iris_data = np.loadtxt(outfile, dtype=float, delimiter=',', skiprows=1, usecols=[1, 2, 3,
4])
petalWidth = iris_data[:,3]
index = np.where(petalWidth > 1.0)
print(index)
print(index[0][0]) # 50
(array([ 50, 51, 52, 53, 54, 55, 56, 58, 59, 61, 63, 64, 65,
66, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 80,
82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 94, 95,
96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108,
109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,
122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134,
135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147,
148, 149], dtype=int64),)
50