Data compression method, data retrieval method, data retrieval apparatus, recording medium, and data packet signal
First Claim
Patent Images
1. A data compression method for efficiently retrieving key data for retrieving main data and compressing a data amount of said key data to be recorded on a recording medium, comprising the steps of:
- comparing first key data composed of a first number of characters with second key data composed of a second number of characters which is greater than said first number of characters of said first key data;
on the basis of a result of the comparison between said first key data and said second key data, detecting the number of matching characters between said first key data and said second key data, deleting a character matching said first key data from said second key data, and generating a data packet having said number of matching characters and a mismatching character obtained by deleting said character matching said first key data from said second key data; and
recording said data packet to said recording medium.
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Abstract
A method of generating a data packet having main data and compressed search data for efficiently retrieving the main data, a retrieval method and a retrieval apparatus for efficiently retrieving the main data by a search key given by plural data packets, a recording medium in which these plural data packets are recorded, and a data packet signal having main data and compressed search data for efficiently retrieving the main data.
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Citations
20 Claims
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1. A data compression method for efficiently retrieving key data for retrieving main data and compressing a data amount of said key data to be recorded on a recording medium, comprising the steps of:
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comparing first key data composed of a first number of characters with second key data composed of a second number of characters which is greater than said first number of characters of said first key data;
on the basis of a result of the comparison between said first key data and said second key data, detecting the number of matching characters between said first key data and said second key data, deleting a character matching said first key data from said second key data, and generating a data packet having said number of matching characters and a mismatching character obtained by deleting said character matching said first key data from said second key data; and
recording said data packet to said recording medium. - View Dependent Claims (2, 3)
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4. A data retrieval method for retrieving main data in a data packet configured by said main data and compressed key data configured by the number of duplicate characters between key data associated with said main data and neighborhood key data and a mismatching character obtained by deleting a duplicate character from said key data, on the basis of an inputted search key and said compressed key data, comprising the steps of:
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retrieving said data packet in which said key data are equal to said mismatching character;
detecting a mismatching portion between a mismatch character of said compressed key data in said data packet retrieved in the retrieving step and said search key; and
if said mismatching portion is detected between said mismatch character of said compressed key data and said search key, detecting a mismatching portion between a mismatch character of said compressed key data of a data packet adjacent to said data packet and said detected mismatching portion. - View Dependent Claims (5, 6)
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7. A data retrieval apparatus for retrieving main data from a recording medium recording a data packet configured by said main data and compressed key data configured by the number of duplicate characters between key data associated with said main data and neighborhood key data and a mismatching character obtained by deleting a duplicate character from said key data, on the basis of an inputted search key and said compressed key data, said data retrieval apparatus comprising:
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recording medium access means for reading said data packet from said recording medium;
retrieval means for retrieving said data packet in which said key data are equal to said mismatching character;
mismatch detecting means for detecting a mismatching character portion between a mismatching character in said compressed key data in a predetermined data packet and an inputted character string for comparison; and
control means for controlling said retrieval means so that said data packet in which said key data are equal to said mismatching character is retrieved, detecting a mismatching portion between the retrieved data packet and said inputted search key by controlling said mismatch detecting means, and, if said mismatching portion is found, detecting, by controlling said mismatch detecting means, a mismatching portion between the detected mismatching portion and a data packet adjacent to the data packet retrieved by said retrieval means read by controlling said recording medium access means. - View Dependent Claims (8, 9, 10, 11)
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12. A data retrieval apparatus for retrieving main data from a recording medium recording a data packet configured by said main data and compressed key data configured by the number of duplicate characters between key data associated with said main data and neighborhood key data and a mismatching character obtained by deleting a duplicate character from said key data, on the basis of an inputted search key and said compressed key data, said data retrieval apparatus comprising:
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recording medium access means for reading said data packet from said recording medium;
operator means for inputting said search key;
display means for displaying said retrieved main data;
compressed key data retrieving means for retrieving said compressed key data from said data packet read from said recording medium;
first comparing means for comparing a mismatching character of said compressed key data with said search key;
holding means for holding, on the basis of a result of the comparison made by said comparing means, the number of mismatching characters between the mismatching character of said compressed key data with said search key;
second comparing means for comparing the number of characters held in said holding means with data indicative of the number of compressed characters; and
control means for controlling said first comparing means so as to compare said search key inputted from said operator means with the number of mismatching characters of the compressed key data retrieved by said compressed key data retrieving means, holding in said holding means the number of matching characters between said search key obtained by comparison by said first comparing means and said compressed key data, comparing said mismatching character of an adjacent data packet with a character string of said search key to be found mismatching by said comparing means, and displaying said main data thus retrieved onto said display means.
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13. A data packet signal having main data and a retrieval character string for retrieving said main data, comprising:
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a main data signal portion;
a mismatching signal portion remaining after compression of a matching character portion between key data for retrieving said main data and key data for another piece of main data; and
a compressed character count signal portion indicative of the number of characters of the compressed data. - View Dependent Claims (14, 15, 16)
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17. A recording medium recording a data packet having main data and compressed data for retrieving said main data, said data packet comprising:
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said main data;
mismatching data remaining after deleting a matching character between retrieval data for retrieving said main data and retrieval data for retrieving main data of a neighboring data packet; and
the number of compressed characters indicative of the number of characters deleted as a result of the matching. - View Dependent Claims (18, 19, 20)
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Specification