Merging

Note: PANDAS MERGE IS ALWAYS SMART ABOUT MATCHING COLUMN NAMES

Inner Joins - Default merge

df_join=pd.merge(df_student, df_gpa)

In no columns to merge are specified, merge identifies columns with matching names.
Inner join preserves the order of the left keys.

Left Joins + Right Joins:

df_join=pd.merge(df_student, df_gpa, how='left')

df_join=pd.merge(df_student, df_gpa, how='right')

Creates one big data frame where it adds the columns of df_gpa either to the left or right of the columns of df_student. It uses index to do so.

Outer Join:

Keeps all parts of your data, fills in the rest with NaN, sort keys lexicographically.

df_join=pd.merge(df_student, df_gpa, how='outer')

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