Question

从熊猫数据框中选择所有行的最简单方法是什么，谁的sym在整个表格中恰好出现两次？例如，在下表中，我想在[＆＃39; b＆＃39;，＆＃39; e＆＃39;]中选择所有带有sym的行，因为这些符号的value_counts等于2.

df=pd.DataFrame({'sym':['a', 'b', 'b', 'c', 'd','d','d','e','e'],'price':np.random.randn(9)})

                     price sym
    0              -0.0129   a
    1              -1.2940   b
    2               1.8423   b
    3              -0.7160   c
    4              -2.3216   d
    5              -0.0120   d
    6              -0.5914   d
    7               0.6280   e
    8               0.5361   e

df.sym.value_counts()
Out[237]: 
d    3
e    2
b    2
c    1
a    1

Answer 1

我认为您可以sym列使用groupby，length == 2使用filter值：

print df.groupby("sym").filter(lambda x: len(x) == 2)
      price sym
1  0.400157   b
2  0.978738   b
7 -0.151357   e
8 -0.103219   e

第二个解决方案使用isin与boolean indexing：

s = df.sym.value_counts()

print s[s == 2].index
Index([u'e', u'b'], dtype='object')

print df[df.sym.isin(s[s == 2].index)]
      price sym
1  0.400157   b
2  0.978738   b
7 -0.151357   e
8 -0.103219   e

使用transform和boolean indexing的最快解决方案：

print (df[df.groupby("sym")["sym"].transform('size') == 2])
    price sym
1 -1.2940   b
2  1.8423   b
7  0.6280   e
8  0.5361   e

Answer 2

您可以使用22:33:10,313 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [net.logstash.logback.appender.LogstashTcpSocketAppender] 22:33:10,379 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [LOGSTASH] 22:33:11,090 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting level of logger [com.sampleapp] to INFO 22:33:11,093 |-INFO in ch.qos.logback.classic.jul.LevelChangePropagator@565f390 - Propagating INFO level on Logger[com.sampleapp] onto the JUL framework 22:33:11,101 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting additivity of logger [com.sampleapp] to false 22:33:11,102 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [FILE-ROLLING] to Logger[com.sampleapp] 22:33:11,105 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting level of logger [org.hibernate] to INFO 22:33:11,105 |-INFO in ch.qos.logback.classic.jul.LevelChangePropagator@565f390 - Propagating INFO level on Logger[org.hibernate] onto the JUL framework 22:33:11,106 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting additivity of logger [org.hibernate] to false 22:33:11,106 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [FILE-ROLLING] to Logger[org.hibernate] 22:33:11,106 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting level of logger [org.hibernate.SQL] to DEBUG 22:33:11,107 |-INFO in ch.qos.logback.classic.jul.LevelChangePropagator@565f390 - Propagating DEBUG level on Logger[org.hibernate.SQL] onto the JUL framework 22:33:11,108 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting additivity of logger [org.hibernate.SQL] to false 22:33:11,109 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [FILE-ROLLING] to Logger[org.hibernate.SQL] 22:33:11,111 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting level of logger [org.hibernate.type.descriptor.sql] to DEBUG 22:33:11,112 |-INFO in ch.qos.logback.classic.jul.LevelChangePropagator@565f390 - Propagating DEBUG level on Logger[org.hibernate.type.descriptor.sql] onto the JUL framework 22:33:11,112 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting additivity of logger [org.hibernate.type.descriptor.sql] to false 22:33:11,113 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [FILE-ROLLING] to Logger[org.hibernate.type.descriptor.sql] 22:33:11,114 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting level of logger [org.springframework] to INFO 22:33:11,114 |-INFO in ch.qos.logback.classic.jul.LevelChangePropagator@565f390 - Propagating INFO level on Logger[org.springframework] onto the JUL framework 22:33:11,114 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting additivity of logger [org.springframework] to false 22:33:11,114 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [FILE-ROLLING] to Logger[org.springframework] 22:33:11,115 |-INFO in ch.qos.logback.classic.joran.action.RootLoggerAction - Setting level of ROOT logger to INFO 22:33:11,116 |-INFO in ch.qos.logback.classic.jul.LevelChangePropagator@565f390 - Propagating INFO level on Logger[ROOT] onto the JUL framework 22:33:11,116 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [FILE-ROLLING] to Logger[ROOT] 22:33:11,116 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [LOGSTASH] to Logger[ROOT] 22:33:11,116 |-INFO in ch.qos.logback.core.joran.action.ShutdownHookAction - About to instantiate shutdown hook of type [ch.qos.logback.core.hook.DelayingShutdownHook] 22:33:11,122 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - End of configuration. 22:33:11,123 |-INFO in org.springframework.boot.logging.logback.SpringBootJoranConfigurator@448c8166 - Registering current configuration as safe fallback point 22:33:11,179 |-INFO in net.logstash.logback.appender.LogstashTcpSocketAppender[LOGSTASH] - Log destination localhost:4560: connection established. 22:33:11,192 |-INFO in ch.qos.logback.classic.jul.LevelChangePropagator@565f390 - Propagating DEBUG level on Logger[com.sampleapp] onto the JUL framework，它应该比使用echo -e "Arquivo nao-estruturado: \c" read nome_arq cp $nome_arq $nome_arq"_clean" arq=$nome_arq"_clean" sed -i 's/%//g;s/()//g;s/\.//g;s/\+//g;s/ Mai /_05_/g;s/ Abr /_04_/g;s/ Mar /\_03_/g;s/\,/\./g' $arq sed -r -i 's/[[:space:]]+/,/g' $arq sed -i 's/Data,Fechamento,Variação,Variação,Abertura,Máxima,Mínima,Volume/ref.date,price.close,var,var.perc,price.open,price.high,price.low,volume/g' $arq和map更快：

groupby

例如

transform

df[df['sym'].map(df['sym'].value_counts()) == 2]

Pandas：根据特定列的值计数选择行

2 个答案: