title: rbind loop in R
body: <p>I have data with 2 million rows and 7 columns. There are also thousands of different companies and indicators. </p>
  
  <p>A sample of the data is:</p>
  
  <pre><code>company_id                                                             indicator_id     X2011
  1    1000045                 AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent   6612429
  2    1000045 AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment        NA
  3    1000045                                                AdjustmentForAmortization        NA
  4    1000045                                                                   Assets 257236034
  5    1000045                                         AssetsHeldForSaleAtCarryingValue   1373001
  6    1000045                      AssetsOfDisposalGroupIncludingDiscontinuedOperation        NA
        X2012     X2013     X2014     X2015
  1   7405579   8924919   7841070   5839000
  2   2111343   2242703   2236449   2462000
  3 -11482251 -13490892 -13852305 -13811000
  4 263835468 283429579 302528591 325309000
  5   1203664   1696330        NA        NA
  6        NA        NA   1746887   2148000
  </code></pre>
  
  <p>and some of the indicators I want are:</p>
  
  <pre><code>    asset_indicators
  [1] "DeferredIncomeTaxExpenseBenefit"                                         
  [2] "CashAndCashEquivalentsAtCarryingValue"                                   
  [3] "CashAndCashEquivalentsPeriodIncreaseDecrease"                            
  [4] "NetCashProvidedByUsedInOperatingActivities"                              
  [5] "NetCashProvidedByUsedInFinancingActivities"                              
  [6] "NetCashProvidedByUsedInInvestingActivities"                              
  [7] "PropertyPlantAndEquipmentNet"                                            
  </code></pre>
  
  <p>I am trying to get a new dataframe with just certain rows. Currently, I have this code:</p>
  
  <pre><code>year &lt;-rbind(statement[which(statement$indicator_id==asset_indicators[1]),],
           statement[which(statement$indicator_id==asset_indicators[2]),],
           statement[which(statement$indicator_id==asset_indicators[3]),],
           statement[which(statement$indicator_id==asset_indicators[4]),],
           statement[which(statement$indicator_id==asset_indicators[5]),],
           statement[which(statement$indicator_id==asset_indicators[6]),],
           statement[which(statement$indicator_id==asset_indicators[7]),] )
  </code></pre>
  
  <p>I'm wondering if there's a way to do this more efficiently? I tried making a for loop but it took hours to run while this takes just a few seconds. It would be nice if it updated automatically if I changed the number of indicators to use.</p>
  
  <p>Does anyone have any ideas how to do this?</p>