# 载入pandas
import pandas as pd
if __name__ == "__main__":
# 以字典来建立DataFrame
d = {
"brand":["Toyota 86", "Subaru BRZ", "NISSAN GT-R", "MAZDA MX-5"],
"auto":[False, True, True, False],
"price":[1300000, 1320000, 6750000, 1340000],
}
data = pd.DataFrame(d)
print(data)## 新增删除操作
"""
brand auto price
0 Toyota 86 False 1300000
1 Subaru BRZ True 1320000
2 NISSAN GT-R True 6750000
3 MAZDA MX-5 False 1340000
"""
# 新增一列
data.loc[4] = ["Toyota Supra", True, 2480000]
print(data)
"""
brand auto price
0 Toyota 86 False 1300000
1 Subaru BRZ True 1320000
2 NISSAN GT-R True 6750000
3 MAZDA MX-5 False 1340000
4 Toyota Supra True 2480000
"""
# 新增一栏
data["color"] = ["黑", "银", "黑", "红", "蓝"]
print(data)
"""
brand auto price color
0 Toyota 86 False 1300000 黑
1 Subaru BRZ True 1320000 银
2 NISSAN GT-R True 6750000 黑
3 MAZDA MX-5 False 1340000 红
4 Toyota Supra True 2480000 蓝
"""
# 删除一列,axis = 0表示删除列
data = data.drop([2], axis = 0)
print(data)
"""
brand auto price color
0 Toyota 86 False 1300000 黑
1 Subaru BRZ True 1320000 银
3 MAZDA MX-5 False 1340000 红
4 Toyota Supra True 2480000 蓝
"""
# 删除一栏,axis = 1表示删除栏
data = data.drop(["color"], axis = 1)
print(data)
"""
brand auto price
0 Toyota 86 False 1300000
1 Subaru BRZ True 1320000
3 MAZDA MX-5 False 1340000
4 Toyota Supra True 2480000
"""
这里要注意,当我们要操作一列时,我们会使用loc属性,loc的中括号必须放索引,但有的时候索引可能不是数字,这时候如果还是想用数字来存取资料,必须使用iloc属性
# 载入pandas
import pandas as pd
if __name__ == "__main__":
# 以字典来建立DataFrame ,索引为["A", "B", "C", "D"]
d = {
"brand":["Toyota 86", "Subaru BRZ", "NISSAN GT-R", "MAZDA MX-5"],
"auto":[False, True, True, False],
"price":[1300000, 1320000, 6750000, 1340000],
}
data = pd.DataFrame(d, index = ["A", "B", "C", "D"])
print(data)
"""
brand auto price
A Toyota 86 False 1300000
B Subaru BRZ True 1320000
C NISSAN GT-R True 6750000
D MAZDA MX-5 False 1340000
"""
#使用索引存取一列
print(data.loc["C"])
"""
brand NISSAN GT-R
auto True
price 6750000
Name: C, dtype: object
"""
#存取由上往下数的第3列(从0开始数)
print(data.iloc[3])
"""
brand MAZDA MX-5
auto False
price 1340000
Name: D, dtype: object
"""
# 载入pandas
import pandas as pd
if __name__ == "__main__":
# 以字典来建立DataFrame,把brand栏位设为索引
d = {
"brand":["Toyota 86", "Subaru BRZ", "NISSAN GT-R", "MAZDA MX-5"],
"auto":[False, True, True, False],
"price":[1300000, 1320000, 6750000, 1340000],
}
data = pd.DataFrame(d)
data = data.set_index("brand")
print(data)
"""
auto price
brand
Toyota 86 False 1300000
Subaru BRZ True 1320000
NISSAN GT-R True 6750000
MAZDA MX-5 False 1340000
"""
#使用索引存取一列
print(data.loc["Toyota 86"])
"""
auto False
price 1300000
Name: Toyota 86, dtype: object
"""
#存取由上往下数的第2列(从0开始数)
print(data.iloc[2])
"""
auto True
price 6750000
Name: NISSAN GT-R, dtype: object
"""
# 载入pandas
import pandas as pd
if __name__ == "__main__":
# 以字典来建立DataFrame
d = {
"brand":["Toyota 86", "Subaru BRZ", "NISSAN GT-R", "MAZDA MX-5"],
"auto":[False, True, True, False],
"price":[1300000, 1320000, 6750000, 1340000],
}
data = pd.DataFrame(d)
print(data)## 新增删除操作
"""
brand auto price
0 Toyota 86 False 1300000
1 Subaru BRZ True 1320000
2 NISSAN GT-R True 6750000
3 MAZDA MX-5 False 1340000
"""
#利用布林遮罩来过滤资料
mask = data["auto"] == False
print(mask)
"""
0 True
1 False
2 False
3 True
Name: auto, dtype: bool
"""
print(data[mask])
"""
brand auto price
0 Toyota 86 False 1300000
3 MAZDA MX-5 False 1340000
"""
print(data[mask]["brand"])
"""
0 Toyota 86
3 MAZDA MX-5
Name: brand, dtype: object
"""
print(data[mask].iloc[0])
"""
brand Toyota 86
auto False
price 1300000
Name: 0, dtype: object
"""
#计算手排车的平均价格
print(data[mask]["price"].mean()) #1320000.0
# 载入pandas
import pandas as pd
if __name__ == "__main__":
# 以字典来建立DataFrame
d = {
"brand":["Toyota 86", "Subaru BRZ", "NISSAN GT-R", "MAZDA MX-5"],
"auto":[False, True, True, False],
"price":[1300000, 1320000, 6750000, 1340000],
}
data = pd.DataFrame(d)
print(data)## 新增删除操作
"""
brand auto price
0 Toyota 86 False 1300000
1 Subaru BRZ True 1320000
2 NISSAN GT-R True 6750000
3 MAZDA MX-5 False 1340000
"""
#利用布林遮罩来过滤资料
mask = data["auto"] == False
#将auto栏位为False的那些资料(手排车)的price栏位设为0
data["price"][mask] = 0
print(data)
"""
brand auto price
0 Toyota 86 False 0
1 Subaru BRZ True 1320000
2 NISSAN GT-R True 6750000
3 MAZDA MX-5 False 0
"""
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