question: private Map < String , Double > findMaxMetricValues ( List < Map < String , String > > dataLines , int start , int end ) { assert ( start < end ) ; Map < String , Double > maxValuesMap = new HashMap < > ( ) ; for ( int index = start ; index < end ; index ++ ) { Map < String , String > data = dataLines . get ( index ) ; for ( String metricKey : data . keySet ( ) ) { String dataValueString = data . get ( metricKey ) ; if ( dataValueString . equals ( NO_DATA ) || ! dataValueString . matches ( DOUBLE_DATA_PATTERN ) ) { continue ; } Double currentMaxValue = maxValuesMap . get ( metricKey ) ; Double dataValue = Double . valueOf ( dataValueString ) ; if ( currentMaxValue == null ) { maxValuesMap . put ( metricKey , dataValue ) ; } else { if ( dataValue > currentMaxValue ) { maxValuesMap . put ( metricKey , dataValue ) ; } } } } return maxValuesMap ; }
target:  Given the data for a file, starting from 'start' index until 'end' index, calculate the maximum value for all metrics found. Only numeric values are calculated.