update

slides/01_intro_python.md

@@ -902,6 +902,33 @@ The basic indexable objects are
      ```
      \normalsize
 
+## 
+
+\setbeamertemplate{itemize item}{\color{red}\tiny$\blacksquare$}
+
+* Selecting data of pandas objects continued
+
+   \vspace{0.5cm}
+
+   * More operations 
+
+     \footnotesize
+
+     ```python
+     df.drop(['col1', 'col2'], axis=1)  # removes columns 'col1' and 'col2'
+     df.fillna(0)                       # fills missing values with 0
+     df.fillna(method='ffill')          # fills missing values with previous 
+                                        # non-missing value in the column
+     df.replace('old_val', 'new_val')   # replaces 'old_val' with 'new_val'
+     df.groupby('col1').mean()          # groups by 'col1' and computes
+                                        # the mean of each group
+     pd.merge(df1, df2, on='column1')   # merges df1 and df2 on 'column1'
+     df['column1'].value_counts()       # counts the number of occurrences
+                                        # of each unique value in 'column'
+     ```
+     \normalsize
+
+   \vspace{3cm}
 
 ##  Pandas - plotting data