Question

我在熊猫中有以下数据框

  code      tank      length      dia       diff
  123       3         625         210       -0.38
  123       5         635         210       1.2

如果diff为正，我只想在长度上加1，连续5次；如果dip为负，我想减1。我想要的数据框看起来像

 code      tank      length       diameter
  123       3         625         210
  123       3         624         210
  123       3         623         210
  123       3         622         210
  123       3         621         210
  123       3         620         210
  123       5         635         210
  123       5         636         210
  123       5         637         210
  123       5         638         210
  123       5         639         210
  123       5         640         210

我正在熊猫里追随。

  df.add(1)

但是，它会将1加到所有列。

Answer 1

使用Index.repeat 6次，然后通过GroupBy.cumcount添加计数器值，最后通过DataFrame.set_index创建默认Cannot instantiate user function：

org.apache.flink.streaming.runtime.tasks.StreamTaskException: Cannot instantiate user function.
    at org.apache.flink.streaming.api.graph.StreamConfig.getStreamOperator(StreamConfig.java:239)
    at org.apache.flink.streaming.runtime.tasks.OperatorChain.createChainedOperator(OperatorChain.java:369)
    at org.apache.flink.streaming.runtime.tasks.OperatorChain.createOutputCollector(OperatorChain.java:296)
    at org.apache.flink.streaming.runtime.tasks.OperatorChain.<init>(OperatorChain.java:133)
    at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:267)
    at org.apache.flink.runtime.taskmanager.Task.run(Task.java:704)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.io.InvalidClassException: scala.Symbol; local class incompatible: stream classdesc serialVersionUID = 6865603221856321286, local class serialVersionUID = 2966401305346518859
    at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:699)
    at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1885)
    at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1751)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2042)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2287)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2211)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2069)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2287)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2211)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2069)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2287)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2211)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2069)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
    at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1975)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1567)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2287)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2211)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2069)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2287)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2211)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2069)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2287)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2211)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2069)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1573)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:431)
    at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:566)
    at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:552)
    at org.apache.flink.util.InstantiationUtil.deserializeObject(InstantiationUtil.java:540)
    at org.apache.flink.util.InstantiationUtil.readObjectFromConfig(InstantiationUtil.java:501)
    at org.apache.flink.streaming.api.graph.StreamConfig.getStreamOperator(StreamConfig.java:224)

或者：

RangeIndex

编辑：

df1 = df.loc[df.index.repeat(6)].copy()
df1['length'] += df1.groupby(level=0).cumcount()
df1 = df1.reset_index(drop=True)

Answer 2

我们可以使用pd.concat，np.cumsum和groupby + .add。

如果要减去，只需将addition * -1乘以，例如：(np.cumsum(np.ones(n))-1) * -1

n = 6

new = pd.concat([df]*n).sort_values(['code', 'length']).reset_index(drop=True)
addition = np.cumsum(np.ones(n))-1
new['length'] = new.groupby(['code', 'tank'])['length'].apply(lambda x: x.add(addition))

输出

    code  tank  length  dia
0    123     3   625.0  210
1    123     3   626.0  210
2    123     3   627.0  210
3    123     3   628.0  210
4    123     3   629.0  210
5    123     3   630.0  210
6    123     5   635.0  210
7    123     5   636.0  210
8    123     5   637.0  210
9    123     5   638.0  210
10   123     5   639.0  210
11   123     5   640.0  210

如何在熊猫的特定列中添加增量编号

2 个答案: