Python数据分析 知识量:13 - 56 - 232
使用drop()函数来删除数据对象中的列,参数为要删除列的名称或列的位置。当参数是列名或位置时,还需要指定参数axis=1,表示删除列。当以列表的形式指定参数columns时,就不需要axis参数了。下面是删除列的示例:
import pandas as pd df=pd.read_excel(r"D:\PythonTestFile\exam.xlsx") print(df.drop(['Chinese','English'],axis=1),'\n') # 指定列的名称 print(df.drop(df.columns[[1,4]],axis=1),'\n') # 指定列的位置 print(df.drop(columns=['Name','Sex'])) # 以列表来指定参数columns
运行结果为:
Name Sex Math 0 Noah male 66 1 Emma female 55 2 Noah male 66 3 Olivia female 44 4 Liam male 69 5 Sophia female 96 6 Liam male 69 7 Isabella female 55 Name Chinese English 0 Noah 90 50 1 Emma 56 56 2 Noah 90 50 3 Olivia 86 87 4 Liam 55 88 5 Sophia 90 66 6 Liam 55 88 7 Isabella 66 85 Chinese English Math 0 90 50 66 1 56 56 55 2 90 50 66 3 86 87 44 4 55 88 69 5 90 66 96 6 55 88 69 7 66 85 55
删除行的操作与删除列相似,仍然使用drop()函数。不同的是,需要使用参数index,且axis=0。
import pandas as pd df=pd.read_excel(r"D:\PythonTestFile\exam.xlsx") print(df.drop([0,1,2],axis=0),'\n') # 指定行的名称 print(df.drop(df.index[[3,4,5]],axis=0),'\n') # 指定行的位置 print(df.drop(index=[6,7])) # 以列表来指定参数index
运行结果为:
Name Sex Chinese English Math 3 Olivia female 86 87 44 4 Liam male 55 88 69 5 Sophia female 90 66 96 6 Liam male 55 88 69 7 Isabella female 66 85 55 Name Sex Chinese English Math 0 Noah male 90 50 66 1 Emma female 56 56 55 2 Noah male 90 50 66 6 Liam male 55 88 69 7 Isabella female 66 85 55 Name Sex Chinese English Math 0 Noah male 90 50 66 1 Emma female 56 56 55 2 Noah male 90 50 66 3 Olivia female 86 87 44 4 Liam male 55 88 69 5 Sophia female 90 66 96
在按照某个条件删除行时,采用的方式并不是直接删除该行,而是排除不满足条件的行后,以筛选后的数据建立新的数据对象。
import pandas as pd df=pd.read_excel(r"D:\PythonTestFile\exam.xlsx") print(df,'\n') new_df=df[df['Chinese']>60] # 删除Chinese<40的行 print(new_df)
运行结果为:
Name Sex Chinese English Math 0 Noah male 90 50 66 1 Emma female 56 56 55 2 Noah male 90 50 66 3 Olivia female 86 87 44 4 Liam male 55 88 69 5 Sophia female 90 66 96 6 Liam male 55 88 69 7 Isabella female 66 85 55 Name Sex Chinese English Math 0 Noah male 90 50 66 2 Noah male 90 50 66 3 Olivia female 86 87 44 5 Sophia female 90 66 96 7 Isabella female 66 85 55
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