Data plotting

• See Python for Data Analysis, Chapter 9

Anatomy of a plot in matplotlib

1. figure: The graphical area for one figure
2. axis: Labeled axis for XY, can be superimposed or tiled
3. plot: Individual shapes (lines, rectangles, etc) drawn on an axis

Types of Plots

• line and scatter graphs
• bar graphs and distributions (histogram vs density)
• other statistics (boxplots)
• image plots (matplotlib commands )
• surface plots (matplotlib commands )

(see plotting in pandas using matplotlib )

Data wrangling

• See Python for Data Analysis, Chapter 8

Hierarchical indexing:

• partial indexing
• unstack() method converts to DataFrame
• stack() is the reverse
• swaplevel() for reordering hierarchical indices
• sort_index() for sorting by one index
• Summary statistics with vector operators, such as sum(level=, axis=)

Combining and merging

• merge() by using keys (indices) like the SQL join operator
  • inner, left, right, and outer joins possible
• concat() for stacking objects

Reshape and pivot

• stack/ vs unstack
• reshape
• “long” vs “wide” format
  • pivot vs melt

Data aggregation

• See Python for Data Analysis, Chapter 10

Groupby: split-apply-combine

• selecting column(s) and index levels
• aggregation functions
• apply() arbitrary functions

Pivot tables and cross-tabulation

• pivot_table
• crosstab