____________
_______________________________
___________
_______
____________
"0908154235"
2-STORY 1946 & NEWER
313
63887
Edwards
"0908154195"
1-STORY 1946 & NEWER ALL STYLES
128
39290
Edwards
There is another issue. These two houses were sold in late 2007, as shown in the LastSoldDate
variable. But the corresponding value in YearBuilt is 2008. It might be that for these houses, the
years in YearBuilt were recorded in early 2008 (another assumption needing confirmation). Update
the YearBuilt variable, this time by using dot notation to assign to two rows.
housing.YearBuilt(checkRows) = 2007;
Clean Up Missing Data
The next step in cleaning the data is to check for missing data in the numeric and categorical
variables. The one logical variable in housing does not support missing values. The ismissing
function indicates which elements of the table have missing values.
missingElements = ismissing(housing)
missingElements = 2930×24 logical array
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
⋮
The ismissing function returns a logical matrix that is the same size as the table. Summing the
columns of that matrix gives the number of missing values in each of the variables of the table.
numMissing = sum(missingElements,1)
numMissing = 1×24
0
0
490
0
0
0
0
0
0
0
0
0
0
0
0
0
Only three of the variables have missing data, but without the variable names it is not easy to tell
which variables they are. One way to tell is to index into the VariableNames property of the table to
find the names that correspond to the variables with missing values.
housing.Properties.VariableNames(numMissing > 0)
ans = 1×3 cell
{'LotFrontage'}
{'BsmtFullBath'}
{'BsmtHalfBath'}
Deciding what to do about missing data is a challenge. If the data is missing at random, and there are
only a few missing values, one strategy is to remove those rows from the table. The four missing
Data Cleaning and Calculations in Tables
9-75