NumPy - Array Manipulation
Several routines are available in NumPy package for manipulation of elements in ndarray object. They can be classified into the following types −
Changing Shape
In NumPy, to change shape is to alter the shape of arrays without changing their data −
| Sr.No. | Shape & Description |
|---|---|
| 1 | reshapeGives a new shape to an array without changing its data |
| 2 | flatA 1-D iterator over the array |
| 3 | flattenReturns a copy of the array collapsed into one dimension |
| 4 | ravelReturns a contiguous flattened array |
Transpose Operations
The NumPy transpose operations swap rows and columns in 2D arrays or rearrange axes in higher-dimensional arrays −
| Sr.No. | Operation & Description |
|---|---|
| 1 | transposePermutes the dimensions of an array |
| 2 | ndarray.TSame as self.transpose() |
| 3 | rollaxisRolls the specified axis backwards |
| 4 | swapaxesInterchanges the two axes of an array |
Changing Dimensions
Changing dimensions of arrays in NumPy involves reshaping or restructuring arrays to fit specific requirements without altering the data −
| Sr.No. | Dimension & Description |
|---|---|
| 1 | broadcastProduces an object that mimics broadcasting |
| 2 | broadcast_toBroadcasts an array to a new shape |
| 3 | expand_dimsExpands the shape of an array |
| 4 | squeezeRemoves single-dimensional entries from the shape of an array |
Joining Arrays
Joining arrays in NumPy concatenate multiple arrays along specified axes −
| Sr.No. | Array & Description |
|---|---|
| 1 | concatenateJoins a sequence of arrays along an existing axis |
| 2 | stackJoins a sequence of arrays along a new axis |
| 3 | hstackStacks arrays in sequence horizontally (column wise) |
| 4 | vstackStacks arrays in sequence vertically (row wise) |
Splitting Arrays
Splitting arrays in NumPy splits arrays into smaller arrays along specified axes −
| Sr.No. | Array & Description |
|---|---|
| 1 | splitSplits an array into multiple sub-arrays |
| 2 | hsplitSplits an array into multiple sub-arrays horizontally (column-wise) |
| 3 | vsplitSplits an array into multiple sub-arrays vertically (row-wise) |
Adding / Removing Elements
Adding or removing elements in NumPy append elements to arrays or remove elements −
| Sr.No. | Element & Description |
|---|---|
| 1 | resizeReturns a new array with the specified shape |
| 2 | appendAppends the values to the end of an array |
| 3 | insertInserts the values along the given axis before the given indices |
| 4 | deleteReturns a new array with sub-arrays along an axis deleted |
| 5 | uniqueFinds the unique elements of an array |