【问题】
I have a tab delimited file that looks as follows:

cat my file.txt

gives:

 1 299

 1 150

 1 50

 1 57

 2 -45

 2 62

 3 515

 3 215

 3 -315

 3 -35

 3 3

 3 6789

 3 34

 5 66

 5 1334

 5 123

I’d like to use Unix commands to get a tab-delimited file that based on values in column#1, each column of the output file will hold all relevant values of column#2 (I’m using here for the example the separator “|” instead of tab only to illustrate my desired output file):

299 | -45| 515| 66

150| 62| 215| 1334

50 | | -315 |

57 | | -35 |

| | 3 |

The corresponding Headers (1,2,3,5; based on column#1 values) could be a nice addition to the code (as shown below), but the main request is to split the information of the first file into separated columns. Thanks!

1| 2| 3| 5

299 | -45| 515| 66

150| 62| 215| 1334

50 | | -315 |

57 | | -35 |

| | 3 |

别人解答：

awk '

BEGIN{max=0;}

{

 d\[$1\]\[length(d\[$1\])+1\] = $2;

 if(length(d\[$1\])>max)

 max = length(d\[$1\]);

}

END{

 PROCINFO\["sorted\_in"\] = "@ind\_num_asc";

 line = "";

 flag = 0;

 for(j in d){

 line = line (flag?"\\t|\\t":"") j;

 flag = 1;

 }

 print line;

 for(i=1; i<=max; ++i){

 line = "";

 flag = 0;

 for(j in d){

 line = line (flag?"\\t|\\t":"") d\[j\]\[i\];

 flag = 1;

 }

 print line;

 }

}' file.txt

you get

1 | 2 | 3 | 5

299 | -45 | 515 | 66

150 | 62 | 215 | 1334

50 | | -315 |

57 | | -35 |

 | | 3 |

Or, you can use python …. for example, in split2Columns.py

import sys

records = \[line.split() for line in open(sys.argv\[1\])\]

import collections

records_dict = collections.defaultdict(list)

for key, val in records:

 records_dict\[key\].append(val)

from itertools import izip_longest

print "\\t|\\t".join(records_dict.keys())

print "\\n".join(("\\t|\\t".join(map(str,l)) for l in izip\_longest(*records\_dict.values(), fillvalue="")))

【回答】
先将数据按第 1 字段分组，生成期望结果集，然后将分组成员竖着填入结果集。

上述算法涉及分组后运算及行转列，如无特殊要求可用 SPL 实现，代码简单易懂：