按日期将行旋转到列 [英] Pivot rows to columns by date pandas

问题描述

我有一个名为df的Pandas DataFrame，如下所示:

I have a Pandas DataFrame called df that looks like this:

Date           String

2016-08-01      a
2016-08-01      b
2016-08-01      c
2016-06-30      d
2016-06-30      e
2016-06-30      f

我正在尝试获取:

Date           Column1      Column2        Column3

2016-08-01       a             b              c
2016-06-30       d             e              f

我尝试使用:

df = pd.pivot_table(df, index='Date')

或:

df.pivot_table(index=['Date'], values="News")

但我一直收到:

pandas.core.base.DataError:没有要聚合的数字类型

pandas.core.base.DataError: No numeric types to aggregate

我该怎么办?

推荐答案

另一种方法是使用groupy，apply(list)，然后用Series.values.tolist()

Another way to do this is with groupy, apply(list) and after that converting the list values to seperate columns with Series.values.tolist()

# Groupby and get the values in a list per unique value of the Date column
df = df.groupby('Date').String.apply(list).reset_index()

    Date        String
0   2016-06-30  [d, e, f]
1   2016-08-01  [a, b, c]

# Convert the values from the list to seperate columns and after that drop the String column
df[['Column1', 'Column2', 'Column3']] = pd.DataFrame(df.String.values.tolist(), index=df.index)
df.drop('String', axis=1, inplace=True)


    Date        Column1 Column2 Column3
0   2016-06-30  d       e       f
1   2016-08-01  a       b       c

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