Make DataFrame's schema valid for importing to BigQuery.
Builds BigQuery input JSON schema based on DataFrame.
Builds BigQuery input JSON schema based on DataFrame. Example schema can be found here: https://cloud.google.com/bigquery/docs/personsDataSchema.json
Make DataFrame's schema valid for importing to BigQuery. The rules are:
1) Valid characters are: letters, digits and underscores 2) All letters must be lowercase