1. A method comprising: identifying a set of topics appearing in text strings included in a plurality of data sources; assigning a topic identifier to each identified topic; associating each topic identifier with a context vector, each context vector representing a frequency of a given identified topic associated with a topic identifier co-occurring in one or more text strings with a plurality of topics from the set of topics and comprising: a plurality of context confidence values, each context confidence value representing a relationship between the given identified topic and an additional identified topic that co-occurs within a text string from the plurality of data sources with the given identified topic; and where each context confidence value of the plurality of context confidence values is based upon a combination of a topic confidence value of the given identified topic and a topic confidence value of the additional identified topic that co-occurs within the text string from the plurality of data sources with the given identified topic; receiving a search query comprising a keyword; identifying one or more topic identifiers associated with the keyword included in the search query; identifying one or more text strings from the plurality of data sources that include topics associated with the identified one or more topic identifiers; and generating a search result for the search query that includes the identified text strings.