[英]Pandas groupby/pivot table for counting values in 2 columns
I have a pandas DataFrame like so我有一个 pandas DataFrame 像这样
week player_a player_b
1 True True
1 True False
1 False False
2 False True
2 False False
2 True False
and I would like to count the number of True and False for each player by week, but I cannot seem to finagle this into a convenient pandas groupby or pivot table operation.我想每周计算每个玩家的 True 和 False 的数量,但我似乎无法将其转换为方便的 pandas groupby 或 pivot 表操作。 The desired result would look like:期望的结果如下所示:
week True False
player
1 player_a 2 1
player_b 1 2
2 player_a 1 2
player_b 1 2
Use pandas pivot_table function and aggregate by size.使用 pandas pivot_table function 并按大小聚合。
df = df.pivot_table(index=['week','player'], columns='value', aggfunc='size', fill_value=0)
Use DataFrame.melt
first and then count crosstab
:先使用DataFrame.melt
然后计算crosstab
:
df1 = df.melt('week', var_name='player')
df = pd.crosstab([df1['week'], df1['player']], df1['value'])
Or use DataFrame.pivot_table
:或使用DataFrame.pivot_table
:
df = df1.pivot_table(index=['week', 'player'], columns='value', fill_value=0, aggfunc='size')
Or aggregate counts by GroupBy.size
and reshape by Series.unstack
:或按GroupBy.size
汇总计数并按Series.unstack
重塑:
df = df1.groupby(['week', 'player', 'value']).size().unstack(fill_value=0)
print (df)
value False True
week player
1 player_a 1 2
player_b 2 1
2 player_a 2 1
player_b 2 1
And solution with DataFrame.stack
, SeriesGroupBy.value_counts
and unstack
:以及使用DataFrame.stack
、 SeriesGroupBy.value_counts
和unstack
的解决方案:
df = df.set_index('week').stack().groupby(level=[0,1]).value_counts().unstack(fill_value=0)
print (df)
False True
week
1 player_a 1 2
player_b 2 1
2 player_a 2 1
player_b 2 1
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