Count the levels of a varlist for a certain condition

[Christine Everaerts]

Hi all,

I was wondering if someone could help me with the following: I need to count the number of product varieties traded between two countries (say A and B) for a specific year.
For example my dataset looks like this:

Year	HS1992	Origin	Destination	TradeVolume
1997	010111	EU	JPN	2000
1997	010119	EU	JPN	230
1998	010111	EU	JPN	2010
1998	010119	EU	JPN	220
1998	071331	EU	JPN	60

I now want to generate a new variable that says how many varieties have been traded between EU and Japan each year, so for 1997 that would be 2 and for 1998 it would be 3.

Is there someone who could help me? Thanks in advance!

Below I posted my data: (but it only contains year 1997 since it's too large)

* Example generated by -dataex-. For more info, type help dataex
clear
input str9 Origin str32 Destination int year str6 HS1992 float TotalTrade
"EU" "JPN" 1997 "852190"  1755.881
"EU" "JPN" 1997 "621010"   275.566
"EU" "JPN" 1997 "292800"  2290.008
"EU" "JPN" 1997 "283539"   955.149
"EU" "JPN" 1997 "293331"   179.384
"EU" "JPN" 1997 "731419"    28.045
"EU" "JPN" 1997 "151221"       1.2
"EU" "JPN" 1997 "200970"   27397.5
"EU" "JPN" 1997 "610799"     54.95
"EU" "JPN" 1997 "620443"  5134.483
"EU" "JPN" 1997 "071331"    25.358
"EU" "JPN" 1997 "820411"  1164.757
"EU" "JPN" 1997 "871620"   736.148
"EU" "JPN" 1997 "620292"  1675.317
"EU" "JPN" 1997 "911190"     5.952
"EU" "JPN" 1997 "840212"     8.903
"EU" "JPN" 1997 "580632"  1673.347
"EU" "JPN" 1997 "521122"     8.083
"EU" "JPN" 1997 "851672"    44.691
"EU" "JPN" 1997 "820130"     55.33
"EU" "JPN" 1997 "560130" 12431.596
"EU" "JPN" 1997 "510710" 17844.895
"EU" "JPN" 1997 "681210"         0
"EU" "JPN" 1997 "701590"   204.809
"EU" "JPN" 1997 "040900"    698.32
"EU" "JPN" 1997 "847321" 16729.518
"EU" "JPN" 1997 "853290"   820.082
"EU" "JPN" 1997 "382340"   580.287
"EU" "JPN" 1997 "850530"   377.295
"EU" "JPN" 1997 "580710"   414.802
"EU" "JPN" 1997 "300630"  226862.7
"EU" "JPN" 1997 "170230"    16.242
"EU" "JPN" 1997 "901819"  97305.35
"EU" "JPN" 1997 "300620"  1042.876
"EU" "JPN" 1997 "200210" 29783.846
"EU" "JPN" 1997 "441191"   335.393
"EU" "JPN" 1997 "850613"   155.599
"EU" "JPN" 1997 "901310"    222.11
"EU" "JPN" 1997 "071310"   315.191
"EU" "JPN" 1997 "560290"   643.313
"EU" "JPN" 1997 "640220"   451.838
"EU" "JPN" 1997 "382200"  95028.84
"EU" "JPN" 1997 "850434"   184.027
"EU" "JPN" 1997 "620620"  1976.014
"EU" "JPN" 1997 "210390"  4294.585
"EU" "JPN" 1997 "610451"  1521.962
"EU" "JPN" 1997 "680990"   341.641
"EU" "JPN" 1997 "821420"  1894.905
"EU" "JPN" 1997 "290544"  2066.072
"EU" "JPN" 1997 "842620"   798.692
"EU" "JPN" 1997 "591120"   181.484
"EU" "JPN" 1997 "851240"  1812.257
"EU" "JPN" 1997 "551632"  2502.844
"EU" "JPN" 1997 "290539" 29810.736
"EU" "JPN" 1997 "170250"  1961.288
"EU" "JPN" 1997 "520531"    56.432
"EU" "JPN" 1997 "630252"   471.324
"EU" "JPN" 1997 "490300"   254.985
"EU" "JPN" 1997 "030799"  4979.343
"EU" "JPN" 1997 "900930"    22.606
"EU" "JPN" 1997 "392114"   860.131
"EU" "JPN" 1997 "291633"    20.057
"EU" "JPN" 1997 "721060"  4102.346
"EU" "JPN" 1997 "300231"         0
"EU" "JPN" 1997 "960899"  1453.865
"EU" "JPN" 1997 "441700" 524.42596
"EU" "JPN" 1997 "621120"   348.481
"EU" "JPN" 1997 "580610"    133.19
"EU" "JPN" 1997 "282710"         0
"EU" "JPN" 1997 "370400"   807.508
"EU" "JPN" 1997 "590900"    343.33
"EU" "JPN" 1997 "283422"         0
"EU" "JPN" 1997 "285100"   337.278
"EU" "JPN" 1997 "100400"         0
"EU" "JPN" 1997 "611211"   141.283
"EU" "JPN" 1997 "170290"   214.453
"EU" "JPN" 1997 "950659"   141.302
"EU" "JPN" 1997 "610459"  1243.831
"EU" "JPN" 1997 "390490" 2082.1218
"EU" "JPN" 1997 "620899"   491.609
"EU" "JPN" 1997 "441111"  1781.858
"EU" "JPN" 1997 "940140"  1338.241
"EU" "JPN" 1997 "260700"    20.064
"EU" "JPN" 1997 "283410"     50.64
"EU" "JPN" 1997 "610791"    25.113
"EU" "JPN" 1997 "790400"     6.745
"EU" "JPN" 1997 "842940" 10250.865
"EU" "JPN" 1997 "151913"   362.515
"EU" "JPN" 1997 "283340"    131.83
"EU" "JPN" 1997 "721070"  3019.649
"EU" "JPN" 1997 "851679"  4331.768
"EU" "JPN" 1997 "110814"         0
"EU" "JPN" 1997 "442090"  3340.538
"EU" "JPN" 1997 "620462"  11748.51
"EU" "JPN" 1997 "841121"         0
"EU" "JPN" 1997 "283640"   191.131
"EU" "JPN" 1997 "854012"  88.68999
"EU" "JPN" 1997 "845020"  7069.271
"EU" "JPN" 1997 "860721"  4549.887
"EU" "JPN" 1997 "970300"  16195.51
end

[Andrew Musau]

isid Origin Destination year HS1992
bys Origin Destination year: gen wanted=_N