从数据框列中查找索引或唯一值 [英] Finding the index or unique values from a dataframe column

问题描述

我有一个数据框

  TableName函数参数
 A func1 3 
 B func1 4 
 A func2 6 
 B func2 2 
 C func1 5 
  

我要首先在数据框中找出唯一的TableName，使用唯一函数很简单。但是，我还需要将唯一索引映射到该值。

  TableName索引
 A 1 3 
 B 2 4 
 C 5 
  

稍后我想将此输出读取为获取唯一的TableName值（例如A），然后使用与之对应的每个索引（依次为1和3）来执行某些操作。

请建议我

解决方案

这是一个 dplyr 解决方案，其中我们创建了一个变量 row_number（），并将其用作我们的索引，即

  df％>％
 mutate（new = row_number（））％>％
 group_by（TableName）％>％
 summarise（Index = toString（new））
  

这给出了

 ＃小注：3 x 2 
 TableName索引
< fct> < chr> 
 1 A 1，3 
 2 B 2，4 
 3 C 5 
  

您也可以将它们另存为列表，而不是字符串，这将使以后的操作更加容易，例如

  df％>％
 mutate（new = row_number（））％&％;％
 group_by（TableName）％&％;％
 summarise（索引=列表（新） ）
  

这样，

 ＃小标题：3 x 2 
 TableName索引
< fct> < list> 
 1 A< int [2]> 
 2 B< int [2]> 
 3 C< int [1]> 
  

I have a dataframe

TableName Function Argument
A         func1    3
B         func1    4
A         func2    6
B         func2    2
C         func1    5

I want to first find out the unique TableName in the dataframe which is simple using unique function. However, I also need the indexes of unique mapped to the value.Something like:

TableName Index
A         1 3
B         2 4
C         5

Later I want to read this output to get the unique TableName value (e.g. A) and then use each index corresponding to it one by one ( 1 and then 3) to perform some operations.

Please suggest me an approach.

解决方案

Here is a dplyr solution where we create a variable with the row_number(), and use that as our index, i.e.

df %>% 
 mutate(new = row_number()) %>% 
 group_by(TableName) %>% 
 summarise(Index = toString(new))

which gives,

# A tibble: 3 x 2
  TableName Index
  <fct>     <chr>
1 A         1, 3 
2 B         2, 4 
3 C         5    

You can also save them as lists rather than strings, which will make future operations easier, i.e.

df %>% 
 mutate(new = row_number()) %>% 
 group_by(TableName) %>% 
 summarise(Index = list(new))

which gives,

# A tibble: 3 x 2
  TableName Index    
  <fct>     <list>   
1 A         <int [2]>
2 B         <int [2]>
3 C         <int [1]>

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