Course Content

# Data Manipulation using pandas

2. Preprocessing Data: Part II

Data Manipulation using pandas

## Challenge

You've solved the first problem with wrong column type. Let's solve the remaining one (with dots). Recall that there are 4 columns with wrong types left (`'morgh', 'valueh', 'grosrth', 'omphtotinch'`

). These columns considered to have dots as indicators for 'Not applicable'. For instance, columns `valueh`

and `grosrth`

are mutually exclusive, since the first one indicates the price of dwelling (i.e., house is owned) and the second one indicates the monthly rent.

The most appropriate way to solve this problem is to replace dots by `NA`

values. In that case, we would be able to manipulate column like a numerical one.

# Task

Perform a replacement of dot symbols `.`

by `NA`

s for `'morgh', 'valueh', 'grosrth', 'omphtotinch'`

columns. Follow the next steps:

- Import the
`NumPy`

library with`np`

alias. - Apply the
`.where()`

method to the`df`

dataframe. - Set the condition what values must remain unchanged. These must be non-dots values.
- Set the
`other`

parameter to`nan`

value from`NumPy`

.

Everything was clear?