Question

我正在寻找向数据框中添加引用该数据框中其他行的信息。数据框具有成对的科学术语，按排名层次排列（物种－属对，属－家庭对等）。我需要在同一行中对源对和目标对都具有taxrank。我在行上有目标taxrank，但需要搜索源单元格是目标的位置，以提取适当的taxrank并将其添加为taxrank列。以下是到目前为止的示例：

TAXRANK_target  target  source
45139    order   Salmoniformes   Protacanthopterygii
45140    family  Salmonidae  Salmoniformes
45201    genus   Salmo   Salmonidae
45202    species    labrax   Salmo
45203    species    carpio   Salmo
45204    species    trutta   Salmo
45205    species    letnica  Salmo
45206    species    marmoratus   Salmo
45207    species    fibreni  Salmo

我希望它看起来像什么

TAXRANK_target  target  source  TAXRANK_source
45139    order   Salmoniformes   Protacanthopterygii    NaN
45140    family  Salmonidae  Salmoniformes  order
45201    genus   Salmo   Salmonidae family
45202    species    labrax   Salmo  genus
45203    species    carpio   Salmo  genus
45204    species    trutta   Salmo  genus
45205    species    letnica  Salmo  genus
45206    species    marmoratus   Salmo  genus
45207    species    fibreni  Salmo  genus
45208    species    obtusirostris    Salmo  genus

我不知道是如何故意引用一行以影响另一行。

Answer 1

由Series.map创建的Series使用DataFrame.set_index：

#if values in target column are not duplicated
s = df.set_index('target')['TAXRANK_target']
#if possible duplicated keep first value only
#s = df.drop_duplicates('target').set_index('target')['TAXRANK_target']
df['TAXRANK_source'] = df['source'].map(s)
print (df)
      TAXRANK_target         target               source TAXRANK_source
45139          order  Salmoniformes  Protacanthopterygii            NaN
45140         family     Salmonidae        Salmoniformes          order
45201          genus          Salmo           Salmonidae         family
45202        species         labrax                Salmo          genus
45203        species         carpio                Salmo          genus
45204        species         trutta                Salmo          genus
45205        species        letnica                Salmo          genus
45206        species     marmoratus                Salmo          genus
45207        species        fibreni                Salmo          genus

如何将列信息添加到引用其他行的Pandas数据框中

1 个答案: