dtype: float64
'''
mySeries1 = mySeries.reindex(['h', 'i', 'j', 'k', 'l', 'm', 'o', 'p', 'q'])
print(mySeries1)
'''
h NaN
i NaN
j NaN
k NaN
l NaN
m NaN
o NaN
p NaN
q NaN
dtype: float64
'''
DataFrame(二维容器)(二维容器)
定义
直接定义(很少用)
导入定义(很常用)
直接定义
import pandas as pd
import numpy as np
df1 = pd.DataFrame(np.arange(10).reshape(2,5))
print(df1)
'''
0 1 2 3 4
0 0 1 2 3 4
1 5 6 7 8 9
'''
导入定义
当pandas包导入一个外部文件时,自动转化为DataFrame对象
df2 = pd.read_csv('src') #src为csv格式的文件路径
import pandas as pd
import numpy as np
df2 = pd.read_csv('src') # src为csv格式的文件路径
df2 = df2[['id', 'diagnosis']] # 投影列index为'id'、'diagnosis'的内容
head()、tail()用于显示数据框的前几条和后几条
查看行和列
# 查看前几行
print(df1.head())
# 查看后几行
print(df1.tail())
# 查看行名,行的显式索引
print(df1.index) # RangeIndex(start=0, stop=25, step=1)
# 计算行数
print(df1.index.size) # 25
print(df1.shape[0]) # 25
# 查看列名
print(df1.columns) # RangeIndex(start=0, stop=4, step=1)
# 计算列数
print(df1.columns.size) # 4
print(df1.shape[1]) # 4