我想编写一个程序，打开一个countryInfo.csv文件，并从每行中提取国家名称，首都城市和人口，然后编写一个名为country_simple_info.csv的新文件，每行中包含国家，资本和人口，这些行按人口规模排序，从大到大。该文件的列包含其他信息，例如大洲，语言等，但是代码应忽略这些信息。以下是我尝试的代码：
import csv
import operator
import sys
with open('countryInfo.csv','r', encoding='utf-8') as csvfile:
reader = csv.DictReader(csvfile, delimiter='\t')
result = sorted(reader, key = lambda d: float(d['population']),reverse = True)
with open('country_simple_info.csv', 'w', encoding='utf-8') as outputFile:
writer = csv.DictWriter(outputFile, reader.fieldnames)
writer.writeheader()
writer.writerows(result)
该代码在必须根据人口对国家排序的部分中效果很好。但是，它将打印文件中的所有内容，而不仅仅是3列。我将如何更改我的代码来做到这一点。下面是输入文件：
iso alpha2 iso alpha3 iso numeric fips code name capital areaInSqKm population continent languages currency geonameId
AD AND 020 AN Andorra Andorra la Vella 468.0 84000 EU ca EUR 3041565
AE ARE 784 AE United Arab Emirates Abu Dhabi 82880.0 4975593 AS ar-AE,fa,en,hi,ur AED 290557
AF AFG 004 AF Afghanistan Kabul 647500.0 29121286 AS fa-AF,ps,uz-AF,tk AFN 1149361
AG ATG 028 AC Antigua and Barbuda St. John's 443.0 86754 NA en-AG XCD 3576396
AI AIA 660 AV Anguilla The Valley 102.0 13254 NA en-AI XCD 3573511
AL ALB 008 AL Albania Tirana 28748.0 2986952 EU sq,el ALL 783754
AM ARM 051 AM Armenia Yerevan 29800.0 2968000 AS hy AMD 174982
AO AGO 024 AO Angola Luanda 1246700.0 13068161 AF pt-AO AOA 3351879
AQ ATA 010 AY Antarctica 1.4E7 0 AN 6697173
AR ARG 032 AR Argentina Buenos Aires 2766890.0 41343201 SA es-AR,en,it,de,fr,gn ARS 3865483
AS ASM 016 AQ American Samoa Pago Pago 199.0 57881 OC en-AS,sm,to USD 5880801
AT AUT 040 AU Austria Vienna 83858.0 8205000 EU de-AT,hr,hu,sl EUR 2782113
AU AUS 036 AS Australia Canberra 7686850.0 21515754 OC en-AU AUD 2077456
AW ABW 533 AA Aruba Oranjestad 193.0 71566 NA nl-AW,pap,es,en AWG 3577279
AX ALA 248 Åland Mariehamn 1580.0 26711 EU sv-AX EUR 661882
AZ AZE 031 AJ Azerbaijan Baku 86600.0 8303512 AS az,ru,hy AZN 587116
BA BIH 070 BK Bosnia and Herzegovina Sarajevo 51129.0 4590000 EU bs,hr-BA,sr-BA BAM 3277605
BB BRB 052 BB Barbados Bridgetown 431.0 285653 NA en-BB BBD 3374084
BD BGD 050 BG Bangladesh Dhaka 144000.0 156118464 AS bn-BD,en BDT 1210997
BE BEL 056 BE Belgium Brussels 30510.0 10403000 EU nl-BE,fr-BE,de-BE EUR 2802361
BF BFA 854 UV Burkina Faso Ouagadougou 274200.0 16241811 AF fr-BF,mos XOF 2361809
BG BGR 100 BU Bulgaria Sofia 110910.0 7148785 EU bg,tr-BG,rom BGN 732800
BH BHR 048 BA Bahrain Manama 665.0 738004 AS ar-BH,en,fa,ur BHD 290291
BI BDI 108 BY Burundi Bujumbura 27830.0 9863117 AF fr-BI,rn BIF 433561
BJ BEN 204 BN Benin Porto-Novo 112620.0 9056010 AF fr-BJ XOF 2395170
BL BLM 652 TB Saint Barthélemy Gustavia 21.0 8450 NA fr EUR 3578476
BM BMU 060 BD Bermuda Hamilton 53.0 65365 NA en-BM,pt BMD 3573345
BN BRN 096 BX Brunei Bandar Seri Begawan 5770.0 395027 AS ms-BN,en-BN BND 1820814
BO BOL 068 BL Bolivia Sucre 1098580.0 9947418 SA es-BO,qu,ay BOB 3923057
BQ BES 535 Bonaire Kralendijk 328.0 18012 NA nl,pap,en USD 7626844
BR BRA 076 BR Brazil Brasília 8511965.0 201103330 SA pt-BR,es,en,fr BRL 3469034
BS BHS 044 BF Bahamas Nassau 13940.0 301790 NA en-BS BSD 3572887
BT BTN 064 BT Bhutan Thimphu 47000.0 699847 AS dz BTN 1252634
BV BVT 074 BV Bouvet Island 49.0 0 AN NOK 3371123
BW BWA 072 BC Botswana Gaborone 600370.0 2029307 AF en-BW,tn-BW BWP 933860
BY BLR 112 BO Belarus Minsk 207600.0 9685000 EU be,ru BYR 630336
BZ BLZ 084 BH Belize Belmopan 22966.0 314522 NA en-BZ,es BZD 3582678
CA CAN 124 CA Canada Ottawa 9984670.0 33679000 NA en-CA,fr-CA,iu CAD 6251999
CC CCK 166 CK Cocos [Keeling] Islands West Island 14.0 628 AS ms-CC,en AUD 1547376
CD COD 180 CG Democratic Republic of the Congo Kinshasa 2345410.0 70916439 AF fr-CD,ln,ktu,kg,sw,lua CDF 203312
CF CAF 140 CT Central African Republic Bangui 622984.0 4844927 AF fr-CF,sg,ln,kg XAF 239880
CG COG 178 CF Republic of the Congo Brazzaville 342000.0 3039126 AF fr-CG,kg,ln-CG XAF 2260494
CH CHE 756 SZ Switzerland Bern 41290.0 7581000 EU de-CH,fr-CH,it-CH,rm CHF 2658434
CI CIV 384 IV Ivory Coast Yamoussoukro 322460.0 21058798 AF fr-CI XOF 2287781
CK COK 184 CW Cook Islands Avarua 240.0 21388 OC en-CK,mi NZD 1899402
CL CHL 152 CI Chile Santiago 756950.0 16746491 SA es-CL CLP 3895114
CM CMR 120 CM Cameroon Yaoundé 475440.0 19294149 AF en-CM,fr-CM XAF 2233387
CN CHN 156 CH China Beijing 9596960.0 1330044000 AS zh-CN,yue,wuu,dta,ug,za CNY 1814991
CO COL 170 CO Colombia Bogotá 1138910.0 47790000 SA es-CO COP 3686110
CR CRI 188 CS Costa Rica San José 51100.0 4516220 NA es-CR,en CRC 3624060
CU CUB 192 CU Cuba Havana 110860.0 11423000 NA es-CU,pap CUP 3562981
CV CPV 132 CV Cape Verde Praia 4033.0 508659 AF pt-CV CVE 3374766
CW CUW 531 UC Curacao Willemstad 444.0 141766 NA nl,pap ANG 7626836
CX CXR 162 KT Christmas Island Flying Fish Cove 135.0 1500 AS en,zh,ms-CC AUD 2078138
CY CYP 196 CY Cyprus Nicosia 9250.0 1102677 EU el-CY,tr-CY,en EUR 146669
CZ CZE 203 EZ Czechia Prague 78866.0 10476000 EU cs,sk CZK 3077311
DE DEU 276 GM Germany Berlin 357021.0 81802257 EU de EUR 2921044
DJ DJI 262 DJ Djibouti Djibouti 23000.0 740528 AF fr-DJ,ar,so-DJ,aa DJF 223816
DK DNK 208 DA Denmark Copenhagen 43094.0 5484000 EU da-DK,en,fo,de-DK DKK 2623032
DM DMA 212 DO Dominica Roseau 754.0 72813 NA en-DM XCD 3575830
DO DOM 214 DR Dominican Republic Santo Domingo 48730.0 9823821 NA es-DO DOP 3508796
DZ DZA 012 AG Algeria Algiers 2381740.0 34586184 AF ar-DZ DZD 2589581
EC ECU 218 EC Ecuador Quito 283560.0 14790608 SA es-EC USD 3658394
EE EST 233 EN Estonia Tallinn 45226.0 1291170 EU et,ru EUR 453733
EG EGY 818 EG Egypt Cairo 1001450.0 80471869 AF ar-EG,en,fr EGP 357994
EH ESH 732 WI Western Sahara Laâyoune / El Aaiún 266000.0 273008 AF ar,mey MAD 2461445
ER ERI 232 ER Eritrea Asmara 121320.0 5792984 AF aa-ER,ar,tig,kun,ti-ER ERN 338010
ES ESP 724 SP Spain Madrid 504782.0 46505963 EU es-ES,ca,gl,eu,oc EUR 2510769
ET ETH 231 ET Ethiopia Addis Ababa 1127127.0 88013491 AF am,en-ET,om-ET,ti-ET,so-ET,sid ETB 337996
FI FIN 246 FI Finland Helsinki 337030.0 5244000 EU fi-FI,sv-FI,smn EUR 660013
FJ FJI 242 FJ Fiji Suva 18270.0 875983 OC en-FJ,fj FJD 2205218
FK FLK 238 FK Falkland Islands Stanley 12173.0 2638 SA en-FK FKP 3474414
FM FSM 583 FM Micronesia Palikir 702.0 107708 OC en-FM,chk,pon,yap,kos,uli,woe,nkr,kpg USD 2081918
FO FRO 234 FO Faroe Islands Tórshavn 1399.0 48228 EU fo,da-FO DKK 2622320
FR FRA 250 FR France Paris 547030.0 64768389 EU fr-FR,frp,br,co,ca,eu,oc EUR 3017382
GA GAB 266 GB Gabon Libreville 267667.0 1545255 AF fr-GA XAF 2400553
GB GBR 826 UK United Kingdom London 244820.0 62348447 EU en-GB,cy-GB,gd GBP 2635167
GD GRD 308 GJ Grenada St. George's 344.0 107818 NA en-GD XCD 3580239
GE GEO 268 GG Georgia Tbilisi 69700.0 4630000 AS ka,ru,hy,az GEL 614540
GF GUF 254 FG French Guiana Cayenne 91000.0 195506 SA fr-GF EUR 3381670
GG GGY 831 GK Guernsey St Peter Port 78.0 65228 EU en,nrf GBP 3042362
GH GHA 288 GH Ghana Accra 239460.0 24339838 AF en-GH,ak,ee,tw GHS 2300660
GI GIB 292 GI Gibraltar Gibraltar 6.5 27884 EU en-GI,es,it,pt GIP 2411586
GL GRL 304 GL Greenland Nuuk 2166086.0 56375 NA kl,da-GL,en DKK 3425505
GM GMB 270 GA Gambia Bathurst 11300.0 1593256 AF en-GM,mnk,wof,wo,ff GMD 2413451
GN GIN 324 GV Guinea Conakry 245857.0 10324025 AF fr-GN GNF 2420477
GP GLP 312 GP Guadeloupe Basse-Terre 1780.0 443000 NA fr-GP EUR 3579143
GQ GNQ 226 EK Equatorial Guinea Malabo 28051.0 1014999 AF es-GQ,fr XAF 2309096
GR GRC 300 GR Greece Athens 131940.0 11000000 EU el-GR,en,fr EUR 390903
GS SGS 239 SX South Georgia and the South Sandwich Islands Grytviken 3903.0 30 AN en GBP 3474415
GT GTM 320 GT Guatemala Guatemala City 108890.0 13550440 NA es-GT GTQ 3595528
GU GUM 316 GQ Guam Hagåtña 549.0 159358 OC en-GU,ch-GU USD 4043988
GW GNB 624 PU Guinea-Bissau Bissau 36120.0 1565126 AF pt-GW,pov XOF 2372248
GY GUY 328 GY Guyana Georgetown 214970.0 748486 SA en-GY GYD 3378535
HK HKG 344 HK Hong Kong Hong Kong 1092.0 6898686 AS zh-HK,yue,zh,en HKD 1819730
HM HMD 334 HM Heard Island and McDonald Islands 412.0 0 AN AUD 1547314
HN HND 340 HO Honduras Tegucigalpa 112090.0 7989415 NA es-HN,cab,miq HNL 3608932
HR HRV 191 HR Croatia Zagreb 56542.0 4284889 EU hr-HR,sr HRK 3202326
HT HTI 332 HA Haiti Port-au-Prince 27750.0 9648924 NA ht,fr-HT HTG 3723988
HU HUN 348 HU Hungary Budapest 93030.0 9982000 EU hu-HU HUF 719819
ID IDN 360 ID Indonesia Jakarta 1919440.0 242968342 AS id,en,nl,jv IDR 1643084
IE IRL 372 EI Ireland Dublin 70280.0 4622917 EU en-IE,ga-IE EUR 2963597
IL ISR 376 IS Israel 20770.0 7353985 AS he,ar-IL,en-IL, ILS 294640
IM IMN 833 IM Isle of Man Douglas 572.0 75049 EU en,gv GBP 3042225
IN IND 356 IN India New Delhi 3287590.0 1173108018 AS en-IN,hi,bn,te,mr,ta,ur,gu,kn,ml,or,pa,as,bh,sat,ks,ne,sd,kok,doi,mni,sit,sa,fr,lus,inc INR 1269750
IO IOT 086 IO British Indian Ocean Territory 60.0 4000 AS en-IO USD 1282588
IQ IRQ 368 IZ Iraq Baghdad 437072.0 29671605 AS ar-IQ,ku,hy IQD 99237
IR IRN 364 IR Iran Tehran 1648000.0 76923300 AS fa-IR,ku IRR 130758
IS ISL 352 IC Iceland Reykjavik 103000.0 308910 EU is,en,de,da,sv,no ISK 2629691
IT ITA 380 IT Italy Rome 301230.0 60340328 EU it-IT,de-IT,fr-IT,sc,ca,co,sl EUR 3175395
JE JEY 832 JE Jersey Saint Helier 116.0 90812 EU en,fr,nrf GBP 3042142
JM JAM 388 JM Jamaica Kingston 10991.0 2847232 NA en-JM JMD 3489940
JO JOR 400 JO Jordan Amman 92300.0 6407085 AS ar-JO,en JOD 248816
JP JPN 392 JA Japan Tokyo 377835.0 127288000 AS ja JPY 1861060
KE KEN 404 KE Kenya Nairobi 582650.0 40046566 AF en-KE,sw-KE KES 192950
KG KGZ 417 KG Kyrgyzstan Bishkek 198500.0 5776500 AS ky,uz,ru KGS 1527747
KH KHM 116 CB Cambodia Phnom Penh 181040.0 14453680 AS km,fr,en KHR 1831722
KI KIR 296 KR Kiribati Tarawa 811.0 92533 OC en-KI,gil AUD 4030945
KM COM 174 CN Comoros Moroni 2170.0 773407 AF ar,fr-KM KMF 921929
KN KNA 659 SC Saint Kitts and Nevis Basseterre 261.0 51134 NA en-KN XCD 3575174
KP PRK 408 KN North Korea Pyongyang 120540.0 22912177 AS ko-KP KPW 1873107
KR KOR 410 KS South Korea Seoul 98480.0 48422644 AS ko-KR,en KRW 1835841
KW KWT 414 KU Kuwait Kuwait City 17820.0 2789132 AS ar-KW,en KWD 285570
KY CYM 136 CJ Cayman Islands George Town 262.0 44270 NA en-KY KYD 3580718
KZ KAZ 398 KZ Kazakhstan Astana 2717300.0 15340000 AS kk,ru KZT 1522867
LA LAO 418 LA Laos Vientiane 236800.0 6368162 AS lo,fr,en LAK 1655842
LB LBN 422 LE Lebanon Beirut 10400.0 4125247 AS ar-LB,fr-LB,en,hy LBP 272103
LC LCA 662 ST Saint Lucia Castries 616.0 160922 NA en-LC XCD 3576468
LI LIE 438 LS Liechtenstein Vaduz 160.0 35000 EU de-LI CHF 3042058
LK LKA 144 CE Sri Lanka Colombo 65610.0 21513990 AS si,ta,en LKR 1227603
LR LBR 430 LI Liberia Monrovia 111370.0 3685076 AF en-LR LRD 2275384
LS LSO 426 LT Lesotho Maseru 30355.0 1919552 AF en-LS,st,zu,xh LSL 932692
LT LTU 440 LH Lithuania Vilnius 65200.0 2944459 EU lt,ru,pl EUR 597427
LU LUX 442 LU Luxembourg Luxembourg 2586.0 497538 EU lb,de-LU,fr-LU EUR 2960313
LV LVA 428 LG Latvia Riga 64589.0 2217969 EU lv,ru,lt EUR 458258
LY LBY 434 LY Libya Tripoli 1759540.0 6461454 AF ar-LY,it,en LYD 2215636
MA MAR 504 MO Morocco Rabat 446550.0 33848242 AF ar-MA,ber,fr MAD 2542007
MC MCO 492 MN Monaco Monaco 1.95 32965 EU fr-MC,en,it EUR 2993457
MD MDA 498 MD Moldova Chişinău 33843.0 4324000 EU ro,ru,gag,tr MDL 617790
ME MNE 499 MJ Montenegro Podgorica 14026.0 666730 EU sr,hu,bs,sq,hr,rom EUR 3194884
MF MAF 663 RN Saint Martin Marigot 53.0 35925 NA fr EUR 3578421
MG MDG 450 MA Madagascar Antananarivo 587040.0 21281844 AF fr-MG,mg MGA 1062947
MH MHL 584 RM Marshall Islands Majuro 181.3 65859 OC mh,en-MH USD 2080185
MK MKD 807 MK Macedonia Skopje 25333.0 2062294 EU mk,sq,tr,rmm,sr MKD 718075
ML MLI 466 ML Mali Bamako 1240000.0 13796354 AF fr-ML,bm XOF 2453866
MM MMR 104 BM Myanmar [Burma] Naypyitaw 678500.0 53414374 AS my MMK 1327865
MN MNG 496 MG Mongolia Ulan Bator 1565000.0 3086918 AS mn,ru MNT 2029969
MO MAC 446 MC Macao Macao 254.0 449198 AS zh,zh-MO,pt MOP 1821275
MP MNP 580 CQ Northern Mariana Islands Saipan 477.0 53883 OC fil,tl,zh,ch-MP,en-MP USD 4041468
MQ MTQ 474 MB Martinique Fort-de-France 1100.0 432900 NA fr-MQ EUR 3570311
MR MRT 478 MR Mauritania Nouakchott 1030700.0 3205060 AF ar-MR,fuc,snk,fr,mey,wo MRO 2378080
MS MSR 500 MH Montserrat Plymouth 102.0 9341 NA en-MS XCD 3578097
MT MLT 470 MT Malta Valletta 316.0 403000 EU mt,en-MT EUR 2562770
MU MUS 480 MP Mauritius Port Louis 2040.0 1294104 AF en-MU,bho,fr MUR 934292
MV MDV 462 MV Maldives Malé 300.0 395650 AS dv,en MVR 1282028
MW MWI 454 MI Malawi Lilongwe 118480.0 15447500 AF ny,yao,tum,swk MWK 927384
MX MEX 484 MX Mexico Mexico City 1972550.0 112468855 NA es-MX MXN 3996063
MY MYS 458 MY Malaysia Kuala Lumpur 329750.0 28274729 AS ms-MY,en,zh,ta,te,ml,pa,th MYR 1733045
MZ MOZ 508 MZ Mozambique Maputo 801590.0 22061451 AF pt-MZ,vmw MZN 1036973
NA NAM 516 WA Namibia Windhoek 825418.0 2128471 AF en-NA,af,de,hz,naq NAD 3355338
NC NCL 540 NC New Caledonia Noumea 19060.0 216494 OC fr-NC XPF 2139685
NE NER 562 NG Niger Niamey 1267000.0 15878271 AF fr-NE,ha,kr,dje XOF 2440476
NF NFK 574 NF Norfolk Island Kingston 34.6 1828 OC en-NF AUD 2155115
NG NGA 566 NI Nigeria Abuja 923768.0 154000000 AF en-NG,ha,yo,ig,ff NGN 2328926
NI NIC 558 NU Nicaragua Managua 129494.0 5995928 NA es-NI,en NIO 3617476
NL NLD 528 NL Netherlands Amsterdam 41526.0 16645000 EU nl-NL,fy-NL EUR 2750405
NO NOR 578 NO Norway Oslo 324220.0 5009150 EU no,nb,nn,se,fi NOK 3144096
NP NPL 524 NP Nepal Kathmandu 140800.0 28951852 AS ne,en NPR 1282988
NR NRU 520 NR Nauru Yaren 21.0 10065 OC na,en-NR AUD 2110425
NU NIU 570 NE Niue Alofi 260.0 2166 OC niu,en-NU NZD 4036232
NZ NZL 554 NZ New Zealand Wellington 268680.0 4252277 OC en-NZ,mi NZD 2186224
OM OMN 512 MU Oman Muscat 212460.0 2967717 AS ar-OM,en,bal,ur OMR 286963
PA PAN 591 PM Panama Panama City 78200.0 3410676 NA es-PA,en PAB 3703430
PE PER 604 PE Peru Lima 1285220.0 29907003 SA es-PE,qu,ay PEN 3932488
PF PYF 258 FP French Polynesia Papeete 4167.0 270485 OC fr-PF,ty XPF 4030656
PG PNG 598 PP Papua New Guinea Port Moresby 462840.0 6064515 OC en-PG,ho,meu,tpi PGK 2088628
PH PHL 608 RP Philippines Manila 300000.0 99900177 AS tl,en-PH,fil,ceb,tgl,ilo,hil,war,pam,bik,bcl,pag,mrw,tsg,mdh,cbk,krj,sgd,msb,akl,ibg,yka,mta,abx PHP 1694008
PK PAK 586 PK Pakistan Islamabad 803940.0 184404791 AS ur-PK,en-PK,pa,sd,ps,brh PKR 1168579
PL POL 616 PL Poland Warsaw 312685.0 38500000 EU pl PLN 798544
PM SPM 666 SB Saint Pierre and Miquelon Saint-Pierre 242.0 7012 NA fr-PM EUR 3424932
PN PCN 612 PC Pitcairn Islands Adamstown 47.0 46 OC en-PN NZD 4030699
PR PRI 630 RQ Puerto Rico San Juan 9104.0 3916632 NA en-PR,es-PR USD 4566966
PS PSE 275 WE Palestine 5970.0 3800000 AS ar-PS ILS 6254930
PT PRT 620 PO Portugal Lisbon 92391.0 10676000 EU pt-PT,mwl EUR 2264397
PW PLW 585 PS Palau Melekeok 458.0 19907 OC pau,sov,en-PW,tox,ja,fil,zh USD 1559582
PY PRY 600 PA Paraguay Asunción 406750.0 6375830 SA es-PY,gn PYG 3437598
QA QAT 634 QA Qatar Doha 11437.0 840926 AS ar-QA,es QAR 289688
RE REU 638 RE Réunion Saint-Denis 2517.0 776948 AF fr-RE EUR 935317
RO ROU 642 RO Romania Bucharest 237500.0 21959278 EU ro,hu,rom RON 798549
RS SRB 688 RI Serbia Belgrade 88361.0 7344847 EU sr,hu,bs,rom RSD 6290252
RU RUS 643 RS Russia Moscow 1.71E7 140702000 EU ru,tt,xal,cau,ady,kv,ce,tyv,cv,udm,tut,mns,bua,myv,mdf,chm,ba,inh,tut,kbd,krc,ava,sah,nog RUB 2017370
RW RWA 646 RW Rwanda Kigali 26338.0 11055976 AF rw,en-RW,fr-RW,sw RWF 49518
SA SAU 682 SA Saudi Arabia Riyadh 1960582.0 25731776 AS ar-SA SAR 102358
SB SLB 090 BP Solomon Islands Honiara 28450.0 559198 OC en-SB,tpi SBD 2103350
SC SYC 690 SE Seychelles Victoria 455.0 88340 AF en-SC,fr-SC SCR 241170
SD SDN 729 SU Sudan Khartoum 1861484.0 35000000 AF ar-SD,en,fia SDG 366755
SE SWE 752 SW Sweden Stockholm 449964.0 9828655 EU sv-SE,se,sma,fi-SE SEK 2661886
SG SGP 702 SN Singapore Singapore 692.7 4701069 AS cmn,en-SG,ms-SG,ta-SG,zh-SG SGD 1880251
SH SHN 654 SH Saint Helena Jamestown 410.0 7460 AF en-SH SHP 3370751
SI SVN 705 SI Slovenia Ljubljana 20273.0 2007000 EU sl,sh EUR 3190538
SJ SJM 744 SV Svalbard and Jan Mayen Longyearbyen 62049.0 2550 EU no,ru NOK 607072
SK SVK 703 LO Slovakia Bratislava 48845.0 5455000 EU sk,hu EUR 3057568
SL SLE 694 SL Sierra Leone Freetown 71740.0 5245695 AF en-SL,men,tem SLL 2403846
SM SMR 674 SM San Marino San Marino 61.2 31477 EU it-SM EUR 3168068
SN SEN 686 SG Senegal Dakar 196190.0 12323252 AF fr-SN,wo,fuc,mnk XOF 2245662
SO SOM 706 SO Somalia Mogadishu 637657.0 10112453 AF so-SO,ar-SO,it,en-SO SOS 51537
SR SUR 740 NS Suriname Paramaribo 163270.0 492829 SA nl-SR,en,srn,hns,jv SRD 3382998
SS SSD 728 OD South Sudan Juba 644329.0 8260490 AF en SSP 7909807
ST STP 678 TP São Tomé and Príncipe São Tomé 1001.0 175808 AF pt-ST STD 2410758
SV SLV 222 ES El Salvador San Salvador 21040.0 6052064 NA es-SV USD 3585968
SX SXM 534 NN Sint Maarten Philipsburg 21.0 37429 NA nl,en ANG 7609695
SY SYR 760 SY Syria Damascus 185180.0 22198110 AS ar-SY,ku,hy,arc,fr,en SYP 163843
SZ SWZ 748 WZ Swaziland Mbabane 17363.0 1354051 AF en-SZ,ss-SZ SZL 934841
TC TCA 796 TK Turks and Caicos Islands Cockburn Town 430.0 20556 NA en-TC USD 3576916
TD TCD 148 CD Chad N'Djamena 1284000.0 10543464 AF fr-TD,ar-TD,sre XAF 2434508
TF ATF 260 FS French Southern Territories Port-aux-Français 7829.0 140 AN fr EUR 1546748
TG TGO 768 TO Togo Lomé 56785.0 6587239 AF fr-TG,ee,hna,kbp,dag,ha XOF 2363686
TH THA 764 TH Thailand Bangkok 514000.0 67089500 AS th,en THB 1605651
TJ TJK 762 TI Tajikistan Dushanbe 143100.0 7487489 AS tg,ru TJS 1220409
TK TKL 772 TL Tokelau 10.0 1466 OC tkl,en-TK NZD 4031074
TL TLS 626 TT East Timor Dili 15007.0 1154625 OC tet,pt-TL,id,en USD 1966436
TM TKM 795 TX Turkmenistan Ashgabat 488100.0 4940916 AS tk,ru,uz TMT 1218197
TN TUN 788 TS Tunisia Tunis 163610.0 10589025 AF ar-TN,fr TND 2464461
TO TON 776 TN Tonga Nuku'alofa 748.0 122580 OC to,en-TO TOP 4032283
TR TUR 792 TU Turkey Ankara 780580.0 77804122 AS tr-TR,ku,diq,az,av TRY 298795
TT TTO 780 TD Trinidad and Tobago Port of Spain 5128.0 1228691 NA en-TT,hns,fr,es,zh TTD 3573591
TV TUV 798 TV Tuvalu Funafuti 26.0 10472 OC tvl,en,sm,gil AUD 2110297
TW TWN 158 TW Taiwan Taipei 35980.0 22894384 AS zh-TW,zh,nan,hak TWD 1668284
TZ TZA 834 TZ Tanzania Dodoma 945087.0 41892895 AF sw-TZ,en,ar TZS 149590
UA UKR 804 UP Ukraine Kiev 603700.0 45415596 EU uk,ru-UA,rom,pl,hu UAH 690791
UG UGA 800 UG Uganda Kampala 236040.0 33398682 AF en-UG,lg,sw,ar UGX 226074
UM UMI 581 U.S. Minor Outlying Islands 0.0 0 OC en-UM USD 5854968
US USA 840 US United States Washington 9629091.0 310232863 NA en-US,es-US,haw,fr USD 6252001
UY URY 858 UY Uruguay Montevideo 176220.0 3477000 SA es-UY UYU 3439705
UZ UZB 860 UZ Uzbekistan Tashkent 447400.0 27865738 AS uz,ru,tg UZS 1512440
VA VAT 336 VT Vatican City Vatican City 0.44 921 EU la,it,fr EUR 3164670
VC VCT 670 VC Saint Vincent and the Grenadines Kingstown 389.0 104217 NA en-VC,fr XCD 3577815
VE VEN 862 VE Venezuela Caracas 912050.0 27223228 SA es-VE VEF 3625428
VG VGB 092 VI British Virgin Islands Road Town 153.0 21730 NA en-VG USD 3577718
VI VIR 850 VQ U.S. Virgin Islands Charlotte Amalie 352.0 108708 NA en-VI USD 4796775
VN VNM 704 VM Vietnam Hanoi 329560.0 89571130 AS vi,en,fr,zh,km VND 1562822
VU VUT 548 NH Vanuatu Port Vila 12200.0 221552 OC bi,en-VU,fr-VU VUV 2134431
WF WLF 876 WF Wallis and Futuna Mata-Utu 274.0 16025 OC wls,fud,fr-WF XPF 4034749
WS WSM 882 WS Samoa Apia 2944.0 192001 OC sm,en-WS WST 4034894
XK XKX 0 KV Kosovo Pristina 10908.0 1800000 EU sq,sr EUR 831053
YE YEM 887 YM Yemen Sanaa 527970.0 23495361 AS ar-YE YER 69543
YT MYT 175 MF Mayotte Mamoudzou 374.0 159042 AF fr-YT EUR 1024031
ZA ZAF 710 SF South Africa Pretoria 1219912.0 49000000 AF zu,xh,af,nso,en-ZA,tn,st,ts,ss,ve,nr ZAR 953987
ZM ZMB 894 ZA Zambia Lusaka 752614.0 13460305 AF en-ZM,bem,loz,lun,lue,ny,toi ZMW 895949
ZW ZWE 716 ZI Zimbabwe Harare 390580.0 13061000 AF en-ZW,sn,nr,nd ZWL 878675
答案 0 :(得分：0)
只需将您想要的fieldnames传递到DictWriter并包含参数extrasaction='ignore'，该参数只会写出您想要的列，例如：
with open('country_simple_info.csv', 'w', encoding='utf-8') as outputFile:
fields = ['name', 'capital', 'population']
writer = csv.DictWriter(outputFile, fields, extrasaction='ignore')
writer.writeheader()
writer.writerows(result)
如果您愿意使用外部库，pandas旨在处理此类信息。您所有的代码都可以替换为（或接近它的东西）：
import pandas as pd
fields = ['name', 'capital', 'population']
df = pd.read_csv('countryInfo.csv', delimiter='\t')
df[fields].sort_values(by='population', ascending=False).to_csv('country_simple_info.csv')