this book would have definitely not been reality without the help and support from some excellent people and organizations that have helped us along this journey first and foremosta big thank you to all our readers for not only reading our books but also supporting us with valuable feedback and insights trulywe have learnt lot from all of you and still continue to do so we would like to acknowledge the entire team at apress for working tirelessly behind the scenes to create and publish quality content for everyone big shout-out goes to the entire python developer communityespecially to the developers of frameworks like numpyscipyscikit-learnspacynltkpandasstatsmodelskerasand tensorflow thanks also to organizations like anacondafor making the lives of data scientists easier and for fostering an amazing ecosystem around data science and machine learning that has been growing exponentially with time we also thank our friendscolleaguesteachersmanagersand well-wishers for supporting us with excellent challengesstrong motivationand good thoughts special mention goes to ram varra for not only being great mentor and guide to usbut also teaching us how to leverage data science as an effective tool from technical aspects as well as from the business and domain perspectives for adding real impact and value we would also like to express our gratitude to our managers and mentorsboth past and presentincluding nagendra venkateshsanjeev reddytamoghna ghosh and sailaja parthasarathy lot of the content in this book wouldn' have been possible without the help from several people and some excellent resources we would like to thank christopher olah for providing some excellent depictions and explanation for lstm models (depiction for lstm models in his blog (excellent pointers on feature engineering techniquesian london for his resources on the visual bag of words model (ian swansonand aaron kramerfor helping us cover lot of ground in model interpretation with skater (information pertaining to wine quality analysis (amazing content especially with regard to time series analysis and recommendation enginesamar lalwani for giving us some vital inputs around time series forecasting with deep learningharish narayanan for an excellent article on neural style transfer (not the leastfrancois chollet for creating keras and writing an excellent book on deep learning would also like to acknowledge and express my gratitude to my parentsdigbijoy and sampamy partner durba and my family and well-wishers for their constant lovesupportand encouragement that drive me to strive to achieve more special thanks to my fellow colleaguesfriendsand co-authors raghav and tushar for slogging many days and nights with me and making this experience worthwhilefinallyonce again would like to thank the entire team at apressespecially sanchita mandalcelestin johnmatthew moodieand our technical reviewerjojo moolayilfor being part of this wonderful journey --dipanjan sarkar xxi