Extracting method, computer product, extracting system, information generating method, and information contents

Abstract

An extracting method includes storing to a storage device: files that include character units; first index information indicating which file includes at least one character unit in a character unit group having a usage frequency less than a predetermined frequency and among character units having common information in a predetermined portion, the usage frequency indicating the extent of files having a given character unit; second index information indicating which file includes a first character unit having a usage frequency at least equal to the predetermined frequency and among the character units having common information in a predetermined portion; and referring to the first and second index information to extract a file having character units in the first and second index information, when a request is received for extraction of a file having the first character unit and a second character unit that is included in the character unit group.

1 . An extracting method executed by a computer, the extracting method comprising:
 storing to a storage device, a plurality of files respectively including character units;   storing to the storage device, first index information indicative of which file includes at least any one of the character units included in a character unit group having a usage frequency that is less than a predetermined frequency and among a plurality of character units that include common information in a predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit;   storing to the storage device, second index information indicative of which file among the plurality of the files, includes a first character unit that has a usage frequency at least equal to the predetermined frequency and is among the character units that include common information in a predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit; and   referring to the first index information and the second index information to extract from the plurality of the files, a file indicated to include character units in the first index information and the second index information, when a request is received for extraction of a file that is among the plurality of the files and includes the first character unit and a second character unit that is included in the character unit group.   
     
     
         2 . The extracting method according to  claim 1 , wherein
 the usage frequency is calculated in advance by counting for each character unit, the number of times the character unit is included in one of the files among the plurality of files, and calculating the usage frequency based on the counted number of times.   
     
     
         3 . The extracting method according to  claim 1 , further comprising:
 storing to the storage device, third index information indicative of which file among the plurality of the files, includes at least any one of the character units included in a character unit group having a usage frequency less than the predetermined frequency and among a plurality of character units that include the second character unit and the common information in another predetermined portion different from the predetermined portion; and   referring to the first index information, the second index information, and the third index information to extract from the plurality of the files, a file indicated to include character units in the first, the second, and the third index information, when the request is received for extraction of a file that is among the plurality of the files and includes the first character unit and the second character unit.   
     
     
         4 . A computer-readable, non-transitory medium storing therein an extracting method that causes a computer to execute a process, the process comprising:
 storing to a storage device, a plurality of files respectively including character units;   storing to the storage device, first index information indicative of which file includes at least any one of the character units included in a character unit group having a usage frequency that is less than a predetermined frequency and among a plurality of character units that include common information in a predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit;   storing to the storage device, second index information indicative of which file among the plurality of the files, includes a first character unit that has a usage frequency at least equal to the predetermined frequency and is among the character units that include common information in a predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit; and   referring to the first index information and the second index information to extract from the plurality of the files, a file indicated to include character units in the first index information and the second index information, when a request is received for extraction of a file that is among the plurality of the files and includes the first character unit and a second character unit that is included in the character unit group.   
     
     
         5 . An extracting system comprising:
 a first apparatus including
 a transmitting unit that is among a plurality of files and transmits a request requesting extraction of a file that includes a first character unit and a second character unit; and 
   a second apparatus including
 a storage device that stores a plurality of files respectively including character units, first index information indicative of which file includes at least any one of the character units included in a character unit group having a usage frequency that is less than a predetermined frequency and among a plurality of character units that include common information in a predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit, and second index information indicative of which file among the plurality of the files, includes a first character unit that has a usage frequency at least equal to the predetermined frequency and is among the character units that include common information in the predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit, and 
 an extracting unit that refers to the first index information and the second index information to extract from the plurality of the files, a file indicated to include character units in the first index information and the second index information, when the request is received. 
   
     
     
         6 . An extracting apparatus comprising:
 a storage device storing a plurality of files respectively including character units; first index information indicative of which file includes at least any one of the character units included in a character unit group having a usage frequency that is less than a predetermined frequency and among a plurality of character units that include common information in a predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit; and second index information indicative of which file among the plurality of the files, includes a first character unit that has a usage frequency at least equal to the predetermined frequency and is among the character units that include common information in a predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit; and   an extractor that refers to the first index information and the second index information to extract from the plurality of the files, a file indicated to include character units in the first index information and the second index information, when a request is received for extraction of a file that is among the plurality of the files and includes the first character unit and a second character unit that is included in the character unit group.   
     
     
         7 . An information generating method executed by a computer, the extracting method comprising:
 generating first index information indicative of which file includes at least one character unit that is included in a character unit group having a usage frequency that is less than a predetermined frequency and among a plurality of character units that include common information in a predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit;   generating second index information indicative of which file among the plurality of the files, includes a first character unit that has a usage frequency at least equal to the predetermined frequency and is among the character units that include common information in the predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit.   
     
     
         8 . The information generating method according to  claim 7 , further comprising:
 counting for each character unit, the number of times the character unit is included in one of the files among the plurality of files; and   determining for each of the character units, whether the character unit is a character unit having a usage frequency that is less than the predetermined frequency or a usage frequency that is at least equal to the predetermined frequency and among the plurality of character units, according to the usage frequency based on the counted number of times.   
     
     
         9 . The information generating method according to  claim 8 , further comprising:
 generating third index information indicative of which file among the plurality of the files, includes at least any one of the character units included in a character unit group having a usage frequency less than the predetermined frequency and among a plurality of character units that include the second character unit and the common information in another predetermined portion different from the predetermined portion.   
     
     
         10 . The information generating method according to  claim 9 , wherein
 the second character unit is character unit made up of two grams,   the predetermined portion is a combination of a character code portion for one of two parts obtained by dividing one of the two grams and a character code for the other of the two grams, which is not divided into two parts, and   the other predetermined portion is a combination of a character code not used for the predetermined portion among character codes obtained by dividing one of the two grams and a character code for the other of the two grams, which is not divided into two parts.   
     
     
         11 . The information generating method according to  claim 7 , wherein
 the second character unit is a character made up of two grams, and   the information generating method further comprising:
 creating a first character code portion and a second character code portion obtained by dividing one gram of the two grams into two parts, and a third character code portion and a fourth character code portion obtained by dividing the other one gram of the two grams into two parts; 
 creating a first predetermined portion by combining the first character code portion and the third character code portion; 
 creating a second predetermined portion by combining the first character code portion and the fourth character code portion; 
 creating a third predetermined portion by combining the second character code portion and the third character code portion; 
 creating a fourth predetermined portion by combining the second character code portion and the fourth character code portion; and 
 creating index information indicative of which of the files includes at least one of the character units that is among a character unit group having at each predetermined portion, code identical to the code at the first predetermined portion, the second predetermined portion, the third predetermined portion, and the fourth predetermined portion the first character unit, not a second character unit included in the character unit group. 
   
     
     
         12 . The information generating method according to  claim 7 , wherein
 the second character unit is a character made up of two grams, wherein   the information generating method further comprising:
 creating a first character code portion group obtained by dividing one gram of the two grams into n parts, and a second character code portion group obtained by dividing the other one gram of the two grams into m parts; 
 creating a plurality of portion specifications by combining any one of the first character code portion group and any one of the second character code portion group; and 
 creating for each of the created portion specifications, index information indicative of which of the files includes at least one of the character units that is among a character unit group having the code of each portion-specified part in common with the first character unit, and not the first character unit included in the character unit group. 
   
     
     
         13 . A computer-readable, non-transitory medium storing therein an information generating program that causes a computer to execute a process, the process comprising:
 generating first index information indicative of which file includes at least one character unit that is included in a character unit group having a usage frequency that is less than a predetermined frequency and among a plurality of character units that include common information in a predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit;   generating second index information indicative of which file among the plurality of the files, includes a first character unit that has a usage frequency at least equal to the predetermined frequency and is among the character units that include common information in the predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit.   
     
     
         14 . A data structure residing on a computer-readable, non-transitory medium, the data structure comprising:
 a plurality of files;   first index information indicative of which file includes at least one character unit that is included in a character unit group having a usage frequency that is less than a predetermined frequency and among a plurality of character units that include common information in a predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit; and   second index information indicative of which file among the plurality of the files, includes a first character unit that has a usage frequency at least equal to the predetermined frequency and is among the character units that include common information in the predetermined portion, the usage frequency being indicative of, among the plurality of the files, the extent of files that include a given character unit.   
     
     
         15 . The data structure according to  claim 14 , further comprising:
 third index information indicative of which file among the plurality of the files, includes at least any one of the character units included in a character unit group having a usage frequency less than the predetermined frequency and among a plurality of character units that include the second character unit and the common information in another predetermined portion different from the predetermined portion.