I have been working with R for several years. R is very strong in data manipulation. I'm learning python and I would like to know how to manipulate data using python. Basically my data sets are organized as data frames (e.g excel sheet). I would like to know (by example) how this kind of basic data manipulation task can be done using python?

```
1. Read csv file like the following

var1, var2, var3
1, 2, 3
4, 5, 6 
7, 8, 9

2. Subset data where var2 in ('5', '8') 
3. Make a new variable --> var4 = var3 * 3
4. Transpose this data
5. Write to csv file

```

Your help and example is most appreciated!