DatabaseDatastore ОбъектВ этом примере показано, как использовать databaseDatastore функция, чтобы создать DatabaseDatastore объект для доступа к наборам данных хранится в базе данных PostgreSQL. После создания DatabaseDatastore объект, можно предварительно просмотреть данные, считать данные во фрагментах и считать каждую запись в наборе данных.
Чтобы анализировать большие данные, можно запустить алгоритмы на больших наборах данных с помощью длинного массива. В качестве альтернативы можно написать алгоритм MapReduce, который определяет фрагментацию и сокращение данных.
Этот пример использует предварительно сконфигурированный источник данных PostgreSQL, чтобы создать соединение с базой данных. Для получения дополнительной информации смотрите databaseConnectionOptions функция.
DatabaseDatastore ОбъектСоздайте собственное соединение с базой данных интерфейса PostgreSQL к базе данных PostgreSQL с помощью имени источника данных, имени пользователя и пароля.
datasource = "PostgreSQLDataSource"; username = "dbdev"; password = "matlab"; conn = postgresql(datasource,username,password);
Создайте DatabaseDatastore объект с помощью соединения с базой данных и SQL-запроса. Этот запрос получает все данные от airlinesmall таблица.
sqlquery = "select * from airlinesmall";
dbds = databaseDatastore(conn,sqlquery); DatabaseDatastore ОбъектПредварительно просмотрите первые восемь записей в наборе данных, возвращенном путем выполнения SQL-запроса.
preview(dbds)
ans=8×29 table
year month dayofmonth dayofweek deptime crsdeptime arrtime crsarrtime uniquecarrier flightnum tailnum actualelapsedtime crselapsedtime airtime arrdelay depdelay origin dest distance taxiin taxiout cancelled cancellationcode diverted carrierdelay weatherdelay nasdelay securitydelay lateaircraftdelay
____ _____ __________ _________ _______ __________ _______ __________ _____________ _________ _________ _________________ ______________ _______ ________ ________ ______ _____ ________ ______ _______ _________ ________________ ________ ____________ ____________ ________ _____________ _________________
1990 9 11 2 1810 1812 1939 1930 "AA" 1426 "NA" 89 78 "NA" 9 -2 "RST" "ORD" 268 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 27 6 1353 1355 1634 1640 "US" 112 "NA" 161 165 "NA" -6 -2 "TPA" "SYR" 1104 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 23 2 1057 1055 1205 1155 "US" 1621 "NA" 68 60 "NA" 10 2 "ROC" "EWR" 246 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 8 1 1515 1440 1609 1535 "NW" 749 "NA" 54 55 "NA" 34 35 "MSP" "FSD" 197 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 19 5 1130 1120 1203 1154 "UA" 369 "NA" 93 94 "NA" 9 10 "BUF" "ORD" 473 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 12 5 1755 1733 1858 1820 "DL" 590 "NA" 63 47 "NA" 38 22 "BOS" "BGR" 201 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
2001 11 22 4 1345 1355 1530 1549 "MQ" 4982 "#NAME?" 105 114 "90" -19 -10 "JAX" "MIA" 334 "8" "7" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
2001 11 26 1 2105 2110 2209 2237 "AA" 1947 "N3BäA1" 64 87 "47" -28 -5 "SFO" "LAX" 337 "6" "11" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
DatabaseDatastore ОбъектСчитайте данные и отобразите первые несколько записей.
data = read(dbds); head(data)
ans=8×29 table
year month dayofmonth dayofweek deptime crsdeptime arrtime crsarrtime uniquecarrier flightnum tailnum actualelapsedtime crselapsedtime airtime arrdelay depdelay origin dest distance taxiin taxiout cancelled cancellationcode diverted carrierdelay weatherdelay nasdelay securitydelay lateaircraftdelay
____ _____ __________ _________ _______ __________ _______ __________ _____________ _________ _________ _________________ ______________ _______ ________ ________ ______ _____ ________ ______ _______ _________ ________________ ________ ____________ ____________ ________ _____________ _________________
1990 9 11 2 1810 1812 1939 1930 "AA" 1426 "NA" 89 78 "NA" 9 -2 "RST" "ORD" 268 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 27 6 1353 1355 1634 1640 "US" 112 "NA" 161 165 "NA" -6 -2 "TPA" "SYR" 1104 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 23 2 1057 1055 1205 1155 "US" 1621 "NA" 68 60 "NA" 10 2 "ROC" "EWR" 246 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 8 1 1515 1440 1609 1535 "NW" 749 "NA" 54 55 "NA" 34 35 "MSP" "FSD" 197 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 19 5 1130 1120 1203 1154 "UA" 369 "NA" 93 94 "NA" 9 10 "BUF" "ORD" 473 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 12 5 1755 1733 1858 1820 "DL" 590 "NA" 63 47 "NA" 38 22 "BOS" "BGR" 201 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
2001 11 22 4 1345 1355 1530 1549 "MQ" 4982 "#NAME?" 105 114 "90" -19 -10 "JAX" "MIA" 334 "8" "7" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
2001 11 26 1 2105 2110 2209 2237 "AA" 1947 "N3BäA1" 64 87 "47" -28 -5 "SFO" "LAX" 337 "6" "11" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
Считайте DatabaseDatastore возразите еще два раза при помощи встречного n. Считайте 10 записей за один раз.
n = 0; while(hasdata(dbds) && n~=2) read(dbds) n = n+1; end
ans=10000×29 table
year month dayofmonth dayofweek deptime crsdeptime arrtime crsarrtime uniquecarrier flightnum tailnum actualelapsedtime crselapsedtime airtime arrdelay depdelay origin dest distance taxiin taxiout cancelled cancellationcode diverted carrierdelay weatherdelay nasdelay securitydelay lateaircraftdelay
____ _____ __________ _________ _______ __________ _______ __________ _____________ _________ ________ _________________ ______________ _______ ________ ________ ______ _____ ________ ______ _______ _________ ________________ ________ ____________ ____________ ________ _____________ _________________
1997 12 10 3 1812 1730 2149 2047 "UA" 1456 "N361UA" 157 137 "139" 62 42 "OAK" "DEN" 957 "8" "10" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1997 12 17 3 1806 1800 1932 1933 "UA" 941 "N1844U" 146 153 "122" -1 6 "ORD" "DEN" 888 "7" "17" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1997 12 27 6 1803 1805 1947 1945 "UA" 2770 "N920UA" 104 100 "86" 2 -2 "PHX" "DEN" 602 "7" "11" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1997 12 27 6 807 800 1138 1130 "UA" 258 "N556UA" 151 150 "112" 8 7 "SFO" "DEN" 967 "8" "31" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1997 12 20 6 1501 1120 1828 1432 "UA" 1164 "N991UA" 147 132 "117" 236 221 "SMF" "DEN" 910 "18" "12" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1998 1 18 7 1207 1211 1358 1355 "HP" 2870 "N186AW" 111 104 "85" 3 -4 "COS" "PHX" 551 "8" "18" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1998 1 22 4 2022 0 2151 0 "AA" 1403 "N218AA" 149 163 "130" -18 -4 "DFW" "PHX" 868 "4" "15" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1998 1 6 2 730 730 840 840 "WN" 760 "N368" 70 70 "56" 0 0 "ELP" "PHX" 347 "5" "9" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1998 1 5 1 730 730 1040 1100 "HP" 2009 "N633AW" 310 330 "282" -20 0 "JFK" "PHX" 2153 "7" "21" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1998 1 16 5 1415 1415 1623 1615 "WN" 1657 "N355" 68 60 "44" 8 0 "LAS" "PHX" 256 "4" "20" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1998 1 28 3 1017 1000 1222 1210 "WN" 924 "N371" 65 70 "57" 12 17 "LAX" "PHX" 370 "2" "6" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1998 1 7 3 2018 2020 2231 2242 "NW" 107 "N540US" 193 202 "164" -11 -2 "MSP" "PHX" 1276 "5" "24" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1998 1 2 5 915 915 1113 1115 "WN" 526 "N627" 58 60 "46" -2 0 "ONT" "PHX" 325 "3" "9" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1998 1 4 7 1035 1030 1332 1356 "US" 163 "N573US" 297 326 "284" -24 5 "PHL" "PHX" 2075 "2" "11" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1998 1 16 5 1235 1210 1436 1415 "WN" 1222 "N342" 61 65 "50" 21 25 "SAN" "PHX" 304 "4" "7" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1998 1 13 2 802 800 1047 1053 "UA" 2903 "N384UA" 105 113 "93" -6 2 "SFO" "PHX" 651 "3" "9" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
⋮
ans=10000×29 table
year month dayofmonth dayofweek deptime crsdeptime arrtime crsarrtime uniquecarrier flightnum tailnum actualelapsedtime crselapsedtime airtime arrdelay depdelay origin dest distance taxiin taxiout cancelled cancellationcode diverted carrierdelay weatherdelay nasdelay securitydelay lateaircraftdelay
____ _____ __________ _________ _______ __________ _______ __________ _____________ _________ _______ _________________ ______________ _______ ________ ________ ______ _____ ________ ______ _______ _________ ________________ ________ ____________ ____________ ________ _____________ _________________
1988 1 5 2 2149 2045 2333 2232 "UA" 202 "NA" 44 47 "NA" 61 64 "ORD" "GRR" 137 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 28 4 1005 1000 1137 1131 "UA" 225 "NA" 152 151 "NA" 6 5 "ORD" "DEN" 888 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 13 3 1159 1200 1514 1518 "UA" 248 "NA" 135 138 "NA" -4 -1 "SFO" "DEN" 967 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 25 1 630 630 948 944 "UA" 270 "NA" 138 134 "NA" 4 0 "LAX" "DEN" 862 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 12 2 2005 1900 2131 2036 "UA" 297 "NA" 146 156 "NA" 55 65 "ORD" "DEN" 888 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 3 7 1153 1155 1202 1205 "UA" 321 "NA" 69 70 "NA" -3 -2 "CMH" "ORD" 296 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 8 5 1227 1200 1413 1330 "UA" 343 "NA" 166 150 "NA" 43 27 "DEN" "SFO" 967 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 29 5 1456 1500 1520 1526 "UA" 364 "NA" 24 26 "NA" -6 -4 "HSV" "BHM" 74 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 27 3 37 40 107 115 "UA" 384 "NA" 30 35 "NA" -8 -3 "SMF" "SFO" 86 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 25 1 638 640 1119 1039 "UA" 408 "NA" 221 179 "NA" 40 -2 "BOI" "ORD" 1437 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 11 1 1313 1130 1615 1434 "UA" 432 "NA" 122 124 "NA" 101 103 "ORD" "BOS" 867 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 19 2 901 842 1051 1036 "UA" 455 "NA" 110 114 "NA" 15 19 "DEN" "TUS" 639 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 12 2 1737 1730 1953 1947 "UA" 475 "NA" 256 257 "NA" 6 7 "JFK" "DEN" 1626 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 12 2 1122 1125 1357 1407 "UA" 494 "NA" 95 102 "NA" -10 -3 "LAS" "DEN" 629 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 13 3 1728 1720 1957 1942 "UA" 519 "NA" 269 262 "NA" 15 8 "BOS" "DEN" 1754 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1988 1 12 2 1559 1500 1844 1745 "UA" 541 "NA" 285 285 "NA" 59 59 "ORD" "SFO" 1846 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
⋮
DatabaseDatastore ОбъектСбросьте DatabaseDatastore возразите против его исходного состояния, где никакие данные не были считаны из него. Сброс позволяет вам перечитывать от того же DatabaseDatastore объект.
reset(dbds)
DatabaseDatastore ОбъектСчитайте каждую запись в DatabaseDatastore объект.
data = readall(dbds);
Отобразите первые три записи полного набора данных.
head(data,3)
ans=3×29 table
year month dayofmonth dayofweek deptime crsdeptime arrtime crsarrtime uniquecarrier flightnum tailnum actualelapsedtime crselapsedtime airtime arrdelay depdelay origin dest distance taxiin taxiout cancelled cancellationcode diverted carrierdelay weatherdelay nasdelay securitydelay lateaircraftdelay
____ _____ __________ _________ _______ __________ _______ __________ _____________ _________ _______ _________________ ______________ _______ ________ ________ ______ _____ ________ ______ _______ _________ ________________ ________ ____________ ____________ ________ _____________ _________________
1990 9 11 2 1810 1812 1939 1930 "AA" 1426 "NA" 89 78 "NA" 9 -2 "RST" "ORD" 268 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 27 6 1353 1355 1634 1640 "US" 112 "NA" 161 165 "NA" -6 -2 "TPA" "SYR" 1104 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
1990 10 23 2 1057 1055 1205 1155 "US" 1621 "NA" 68 60 "NA" 10 2 "ROC" "EWR" 246 "NA" "NA" 0 "NA" 0 "NA" "NA" "NA" "NA" "NA"
DatabaseDatastore Объект и соединение с базой данныхclose(dbds)
postgresql | databaseDatastore | preview | read | readall | reset | close