pandas - delete a row or column of data

首先,創建一個DataFrameFormat data as example data.

# 創建一個DataFrame格式數據
data = {
'a': ['a0', 'a1', 'a2'],
'b': ['b0', 'b1', 'b2'],
'c': [i for i in range(3)],
'd': 4}
df = pd.DataFrame(data)
print('Example data situation：\n', df)

注：DataFrame是最常用的pandas對象,使用pandasAfter reading the data file,數據就以DataFrame數據結構存儲在內存中.

pandasData row and column deletion,主要用到drop()和del函數,用法如下：
1、drop()函數
語法：
DataFrame.drop(labels,axis=0,level=None,inplace=False,errors=’raise’)

參數說明labels接收string或array,Label representing the row or column to delete（行名或列名）.無默認值axis接收0或1,Represents the axis of the operation（行或列）.默認為0,代表行;1為列.level接收int或索引名,代表標簽所在級別.默認為Noneinplace接收布爾值,代表操作是否對原數據生效,默認為Falseerrorserrors='raise’will let the program inlabelsAn error is thrown when an missing row or column name is received and the program stops,errors='ignore’Row or column names that are not present are ignored,Only operate on existing row or column names.默認為‘errors=‘raise’’.

實例1：刪除d列

df1 = df.drop(labels='d', axis=1)
print('刪除d列前：\n', df)
print('刪除d列後：\n', df1)

實例2：刪除第一行

df2 = df.drop(labels=0)
print('刪除前：\n', df)
print('刪除列：\n', df2)

實例3：Delete multiple rows and multiple columns at the same time

df3 = df.drop(labels=['a', 'b'], axis=1) # 同時刪除a,b列
df4 = df.drop(labels=range(2)) # 等價於df.drop(labels=[0,1])
print('刪除前：\n', df)
print('刪除多列（a,b）:\n', df3)
print('刪除多行(第1,2行)：\n', df4)

注意：（1）、When deleting a column,axis參數不可省,因為axis默認為0（行）;
（2）、沒有加入inplace參數,By default, the original data will not be modified,The result needs to be assigned to a new variable.

2、del函數
語法：del df[‘列名’]
This operation is performed on the original datadf進行刪除,And only one column can be deleted at a time.
正確用法：

del df['d']
print('原地刪除d列後：\n', df)

錯誤用法:

del df[['a', 'b']]
print(df)

以上就是pandasDelete the usage of a row and a column of data,drop()相對於del()來說,靈活性更高,更為實用.

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