[SPARK-7035] Encourage __getitem__ over __getattr__ on column access in the Python DataFrame API
[SPARK-7035] Encourage __getitem__ over __getattr__ on column access in the Python DataFrame API

Author: ksonj <kson@siberie.de>

Closes #5971 from ksonj/doc and squashes the following commits:

dadfebb [ksonj] __getitem__ is cleaner than __getattr__

aosagie/spark,darionyaphet/spark,SnappyDataInc/spark,JerryLead/spark,shubhamchopra/spark,nlalevee/spark,chuckchen/spark,dhruve/spark,aokolnychyi/spark,liyichao/spark,bdrillard/spark,panfengfeng/spark,ibm-research-ireland/sparkoscope,publicRoman/spark,apache/spark,SHASHANKB/spark,MLnick/spark,jlopezmalla/spark,holdenk/spark,patrick-nicholson/spark,WeichenXu123/spark,ajaysaini725/spark,kevinyu98/spark,SHASHANKB/spark,spark-test/spark,rikima/spark,panfengfeng/spark,ddna1021/spark,adrian-ionescu/apache-spark,ueshin/apache-spark,michalsenkyr/spark,saltstar/spark,mahak/spark,jianran/spark,nilsgrabbert/spark,joseph-torres/spark,yanboliang/spark,hvanhovell/spark,debugger87/spark,brad-kaiser/spark,zzcclp/spark,byakuinss/spark,srowen/spark,someorz/spark,liyichao/spark,metamx/spark,haowu80s/spark,dbtsai/spark,andrewor14/spark,saltstar/spark,taroplus/spark,shuangshuangwang/spark,liutang123/spark,setjet/spark,saturday-shi/spark,setjet/spark,rednaxelafx/apache-spark,icexelloss/spark,pgandhi999/spark,jkbradley/spark,ConeyLiu/spark,ahnqirage/spark,bOOm-X/spark,bravo-zhang/spark,big-pegasus/spark,JoshRosen/spark,sureshthalamati/spark,pronix/spark,ioana-delaney/spark,chuckchen/spark,huang1900/spark,techaddict/spark,sahilTakiar/spark,wangmiao1981/spark,aray/spark,lvdongr/spark,jiangxb1987/spark,Aegeaner/spark,debugger87/spark,dhruve/spark,apache-spark-on-k8s/spark,mahak/spark,janewangfb/spark,alunarbeach/spark,pronix/spark,cloud-fan/spark,witgo/spark,cin/spark,holdenk/spark,wzhfy/spark,janewangfb/spark,milliman/spark,minixalpha/spark,szhem/spark,dbtsai/spark,xuanyuanking/spark,tengpeng/spark,panfengfeng/spark,joseph-torres/spark,Panos-Bletsos/spark-cost-model-optimizer,sachintyagi22/spark,mahak/spark,poffuomo/spark,gengliangwang/spark,lxsmnv/spark,markhamstra/spark,dhruve/spark,loneknightpy/spark,publicRoman/spark,xflin/spark,icexelloss/spark,goldmedal/spark,techaddict/spark,haowu80s/spark,jiangxb1987/spark,mzl9039/spark,hvanhovell/spark,lvdongr/spark,dongjoon-hyun/spark,kimoonkim/spark,rikima/spark,pronix/spark,apache/spark,dhruve/spark,shuangshuangwang/spark,janewangfb/spark,map222/spark,rekhajoshm/spark,mdespriee/spark,liutang123/spark,maropu/spark,srowen/spark,aray/spark,spark-test/spark,techaddict/spark,haowu80s/spark,zero323/spark,publicRoman/spark,rikima/spark,tejasapatil/spark,kevinyu98/spark,dbtsai/spark,nchammas/spark,someorz/spark,darionyaphet/spark,techaddict/spark,zhouyejoe/spark,pronix/spark,holdenk/spark,shuangshuangwang/spark,highfei2011/spark,srowen/spark,guoxiaolongzte/spark,xflin/spark,WeichenXu123/spark,ajaysaini725/spark,pgandhi999/spark,publicRoman/spark,zuotingbing/spark,publicRoman/spark,saltstar/spark,brad-kaiser/spark,apache/spark,panfengfeng/spark,kevinyu98/spark,byakuinss/spark,goldmedal/spark,rednaxelafx/apache-spark,HyukjinKwon/spark,HyukjinKwon/spark,haowu80s/spark,LantaoJin/spark,kimoonkim/spark,darionyaphet/spark,JoshRosen/spark,tengpeng/spark,bravo-zhang/spark,icexelloss/spark,aray/spark,akopich/spark,poffuomo/spark,SnappyDataInc/spark,wangmiao1981/spark,yanboliang/spark,kiszk/spark,apache-spark-on-k8s/spark,nchammas/spark,byakuinss/spark,jiangxb1987/spark,LantaoJin/spark,ericvandenbergfb/spark,Panos-Bletsos/spark-cost-model-optimizer,gengliangwang/spark,xuanyuanking/spark,sahilTakiar/spark,poffuomo/spark,jianran/spark,bOOm-X/spark,JerryLead/spark,zuotingbing/spark,witgo/spark,vinodkc/spark,skonto/spark,caneGuy/spark,setjet/spark,jiangxb1987/spark,cloud-fan/spark,szhem/spark,alunarbeach/spark,andrewor14/spark,lxsmnv/spark,sureshthalamati/spark,liyichao/spark,icexelloss/spark,dbtsai/spark,zero323/spark,HyukjinKwon/spark,SHASHANKB/spark,BryanCutler/spark,nilsgrabbert/spark,actuaryzhang/spark,goldmedal/spark,HyukjinKwon/spark,ddna1021/spark,patrick-nicholson/spark,ptkool/spark,zzcclp/spark,xuanyuanking/spark,apache/spark,MLnick/spark,aokolnychyi/spark,UndeadBaneGitHub/spark,witgo/spark,LantaoJin/spark,eyalfa/spark,jrshust/spark,andrewor14/spark,adrian-ionescu/apache-spark,apache/spark,Aegeaner/spark,poffuomo/spark,dongjoon-hyun/spark,facaiy/spark,skonto/spark,kevinyu98/spark,ptkool/spark,brad-kaiser/spark,WeichenXu123/spark,kevinyu98/spark,actuaryzhang/spark,techaddict/spark,ioana-delaney/spark,andrewor14/spark,akopich/spark,michalsenkyr/spark,jianran/spark,dongjoon-hyun/spark,ibm-research-ireland/sparkoscope,publicRoman/spark,skonto/spark,byakuinss/spark,JerryLead/spark,janewangfb/spark,vinodkc/spark,jlopezmalla/spark,tengpeng/spark,kimoonkim/spark,tengpeng/spark,spark-test/spark,kimoonkim/spark,hvanhovell/spark,jrshust/spark,mzl9039/spark,nilsgrabbert/spark,milliman/spark,sureshthalamati/spark,szhem/spark,UndeadBaneGitHub/spark,ericvandenbergfb/spark,nlalevee/spark,shuangshuangwang/spark,zuotingbing/spark,caneGuy/spark,metamx/spark,andrewor14/spark,dbtsai/spark,markhamstra/spark,LantaoJin/spark,SHASHANKB/spark,MLnick/spark,mike0sv/spark,bdrillard/spark,mdespriee/spark,huang1900/spark,liyichao/spark,chuckchen/spark,alunarbeach/spark,markhamstra/spark,ahnqirage/spark,shaneknapp/spark,nchammas/spark,actuaryzhang/spark,WeichenXu123/spark,bOOm-X/spark,Panos-Bletsos/spark-cost-model-optimizer,markhamstra/spark,lvdongr/spark,holdenk/spark,ueshin/apache-spark,shaneknapp/spark,sachintyagi22/spark,byakuinss/spark,rezasafi/spark,chuckchen/spark,apache-spark-on-k8s/spark,setjet/spark,rekhajoshm/spark,wzhfy/spark,debugger87/spark,shubhamchopra/spark,rednaxelafx/apache-spark,SHASHANKB/spark,alunarbeach/spark,HyukjinKwon/spark,ron8hu/spark,liutang123/spark,xflin/spark,nlalevee/spark,milliman/spark,shaneknapp/spark,ibm-research-ireland/sparkoscope,facaiy/spark,narahari92/spark,Aegeaner/spark,ahnqirage/spark,maropu/spark,kimoonkim/spark,guoxiaolongzte/spark,aosagie/spark,poffuomo/spark,xuanyuanking/spark,lvdongr/spark,loneknightpy/spark,someorz/spark,SnappyDataInc/spark,nilsgrabbert/spark,goldmedal/spark,ueshin/apache-spark,lxsmnv/spark,akopich/spark,rekhajoshm/spark,wangyum/spark,kissmetrics/spark,cloud-fan/spark,lxsmnv/spark,1haodian/spark,loneknightpy/spark,huang1900/spark,aosagie/spark,srowen/spark,zero323/spark,srowen/spark,wangyum/spark,debugger87/spark,Panos-Bletsos/spark-cost-model-optimizer,ibm-research-ireland/sparkoscope,janewangfb/spark,cloud-fan/spark,apache-spark-on-k8s/spark,mzl9039/spark,zero323/spark,lxsmnv/spark,SnappyDataInc/spark,saltstar/spark,andrewor14/spark,Aegeaner/spark,ericvandenbergfb/spark,map222/spark,maropu/spark,SnappyDataInc/spark,Panos-Bletsos/spark-cost-model-optimizer,sahilTakiar/spark,alunarbeach/spark,ron8hu/spark,1haodian/spark,aokolnychyi/spark,ptkool/spark,esi-mineset/spark,mike0sv/spark,saturday-shi/spark,bdrillard/spark,rezasafi/spark,shubhamchopra/spark,ericvandenbergfb/spark,wzhfy/spark,michalsenkyr/spark,zhouyejoe/spark,byakuinss/spark,xflin/spark,dhruve/spark,1haodian/spark,hvanhovell/spark,ConeyLiu/spark,wangyum/spark,apache/spark,lxsmnv/spark,WindCanDie/spark,joseph-torres/spark,gioenn/xSpark,mahak/spark,panfengfeng/spark,panfengfeng/spark,ptkool/spark,MLnick/spark,metamx/spark,skonto/spark,bOOm-X/spark,guoxiaolongzte/spark,HyukjinKwon/spark,nlalevee/spark,esi-mineset/spark,bravo-zhang/spark,pgandhi999/spark,akopich/spark,BryanCutler/spark,michalsenkyr/spark,ibm-research-ireland/sparkoscope,bOOm-X/spark,michalsenkyr/spark,akopich/spark,big-pegasus/spark,vinodkc/spark,saturday-shi/spark,wzhfy/spark,saturday-shi/spark,JerryLead/spark,darionyaphet/spark,liutang123/spark,dongjoon-hyun/spark,mike0sv/spark,markhamstra/spark,facaiy/spark,wangmiao1981/spark,kimoonkim/spark,minixalpha/spark,metamx/spark,narahari92/spark,panfengfeng/spark,spark-test/spark,Panos-Bletsos/spark-cost-model-optimizer,JoshRosen/spark,1haodian/spark,ddna1021/spark,hvanhovell/spark,shubhamchopra/spark,milliman/spark,rikima/spark,UndeadBaneGitHub/spark,ericvandenbergfb/spark,saltstar/spark,witgo/spark,rednaxelafx/apache-spark,xflin/spark,highfei2011/spark,spark-test/spark,bOOm-X/spark,guoxiaolongzte/spark,taroplus/spark,dbtsai/spark,aosagie/spark,jkbradley/spark,mahak/spark,mdespriee/spark,someorz/spark,Aegeaner/spark,aosagie/spark,JerryLead/spark,ueshin/apache-spark,chuckchen/spark,big-pegasus/spark,BryanCutler/spark,kissmetrics/spark,nlalevee/spark,jkbradley/spark,JerryLead/spark,nilsgrabbert/spark,ron8hu/spark,dhruve/spark,rikima/spark,gioenn/xSpark,aokolnychyi/spark,bOOm-X/spark,mzl9039/spark,kiszk/spark,WindCanDie/spark,LantaoJin/spark,wzhfy/spark,kiszk/spark,WeichenXu123/spark,xuanyuanking/spark,ron8hu/spark,xflin/spark,rezasafi/spark,big-pegasus/spark,hvanhovell/spark,Aegeaner/spark,michalsenkyr/spark,szhem/spark,kissmetrics/spark,big-pegasus/spark,zuotingbing/spark,mdespriee/spark,SnappyDataInc/spark,wangyum/spark,eyalfa/spark,facaiy/spark,kiszk/spark,mzl9039/spark,milliman/spark,WindCanDie/spark,saturday-shi/spark,ddna1021/spark,UndeadBaneGitHub/spark,ueshin/apache-spark,facaiy/spark,zzcclp/spark,nchammas/spark,UndeadBaneGitHub/spark,joseph-torres/spark,huang1900/spark,highfei2011/spark,srowen/spark,joseph-torres/spark,patrick-nicholson/spark,pgandhi999/spark,skonto/spark,loneknightpy/spark,big-pegasus/spark,JoshRosen/spark,ajaysaini725/spark,bravo-zhang/spark,liutang123/spark,caneGuy/spark,liyichao/spark,apache-spark-on-k8s/spark,tejasapatil/spark,bdrillard/spark,vinodkc/spark,kissmetrics/spark,akopich/spark,liutang123/spark,stanzhai/spark,mike0sv/spark,kissmetrics/spark,LantaoJin/spark,yanboliang/spark,chuckchen/spark,darionyaphet/spark,szhem/spark,narahari92/spark,goldmedal/spark,minixalpha/spark,adrian-ionescu/apache-spark,zzcclp/spark,esi-mineset/spark,dbtsai/spark,joseph-torres/spark,nchammas/spark,shubhamchopra/spark,JoshRosen/spark,adrian-ionescu/apache-spark,SHASHANKB/spark,stanzhai/spark,spark-test/spark,gengliangwang/spark,wangmiao1981/spark,icexelloss/spark,icexelloss/spark,ron8hu/spark,markhamstra/spark,someorz/spark,minixalpha/spark,chuckchen/spark,cin/spark,kissmetrics/spark,JoshRosen/spark,maropu/spark,BryanCutler/spark,eyalfa/spark,jkbradley/spark,metamx/spark,sachintyagi22/spark,shaneknapp/spark,ron8hu/spark,srowen/spark,sahilTakiar/spark,WeichenXu123/spark,narahari92/spar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tgo/spark,hhbyyh/spark,jiangxb1987/spark,rekhajoshm/spark,brad-kaiser/spark,dongjoon-hyun/spark,eyalfa/spark,WindCanDie/spark,tejasapatil/spark,loneknightpy/spark,mike0sv/spark,cloud-fan/spark,aokolnychyi/spark,liyichao/spark,aray/spark,ibm-research-ireland/sparkoscope,cloud-fan/spark,sahilTakiar/spark,cin/spark,gengliangwang/spark,techaddict/spark,rikima/spark,gioenn/xSpark,rednaxelafx/apache-spark,caneGuy/spark,ioana-delaney/spark,zzcclp/spark,brad-kaiser/spark,ioana-delaney/spark,cin/spark,patrick-nicholson/spark,hhbyyh/spark,ptkool/spark,JerryLead/spark,jlopezmalla/spark,liutang123/spark,zhouyejoe/spark,sahilTakiar/spark,shaneknapp/spark,ConeyLiu/spark,goldmedal/spark,szhem/spark,saturday-shi/spark,aokolnychyi/spark