To replace all NaN elements of the matrix B with zero, use B(isnan(B)) = 0 For example, you could replace all the NaN elements in an array with another value by using a combination of isnan, logical indexing, and scalar expansion. Many MATLAB functions that start with is return logical arrays and are very useful for logical indexing. For example, A(A > 12) extracts all the elements of A that are greater than 12. The output is always in the form of a column vector. MATLAB extracts the matrix elements corresponding to the nonzero values of the logical array. In logical indexing, you use a single, logical array for the matrix subscript. This form of indexed assignment is called scalar expansion.Īnother indexing variation, logical indexing, has proven to be both useful and expressive. You can always, however, use a scalar on the right side: v() = 30 % Replace second and third elements by 30 Usually the number of elements on the right must be the same as the number of elements referred to by the indexing expression on the left. V(end:-1:1) % Reverse the order of elementsīy using an indexing expression on the left side of the equal sign, you can replace certain elements of the vector: v() = % Replace some elements of v You can even do arithmetic using end: v(2:end-1) % Extract the second through the next-to-last elementsĬombine the colon operator and end to achieve a variety of effects, such as extracting every k-th element or flipping the entire vector: v(1:2:end) % Extract all the odd elements The end operator can be used in a range: v(5:end) % Extract the fifth through the last elements The special end operator is an easy shorthand way to refer to the last element of v: v(end) % Extract the last element Swap the two halves of v to make a new vector: v2 = v() % Extract and swap the halves of v The colon notation in MATLAB provides an easy way to extract a range of elements from v: v(3:7) % Extract the third through the seventh elements Or the subscript can itself be another vector: v() % Extract the first, fifth, and sixth elements The subscript can be a single value: v(3) % Extract the third element Trailing rows and columns that do not contain data.Let's start with the simple case of a vector and a single subscript. The importing functionĪutomatically detects the used range by trimming any leading and The spreadsheet that actually contains data. Note: Used Range refers to the rectangular portion of If unspecified, the importing function automatically detects Named ranges exist in a spreadsheet, then the importing function can For instance, you can select a rectangular portion of In Excel, you can create names to identify ranges in the Reading from the specified first row to the end of the data or the Importing function automatically detects the extent of the data by Specify the first row containing the data using the positive The specified range must match the number specified in the The row extent by reading from the first nonempty row to the end of Specified column range, the import function automatically detects Range by identifying the beginning and ending columns using Range, the importing function automatically detects the columnĮxtent by reading from the first nonempty column to the end of theĭata, and creates one variable per column. Specify the range by identifying the beginning and ending rows Specified range are imported as missing cells. Forĭata contained in the specified range. Start-row, start-column, end-row, and end-column. Using a four element numeric vector containing Opposing corners that define the region to read in Import 10 rows of the first 5 variables from the worksheet named '2007'. Year Month DayofMonth DayOfWeek DepTime CRSDepTime ArrTime CRSArrTime UniqueCarrier FlightNum TailNum ActualElapsedTime CRSElapsedTime AirTime ArrDelay DepDelay Origin Dest Distance TaxiIn TaxiOut Cancelled CancellationCode Diverted CarrierDelay WeatherDelay SDelay SecurityDelay LateAircraftDelay
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