这篇文章主要介绍了 numpy中ndarray数组对象怎么用，具有一定借鉴价值，感兴趣的朋友可以参考下，希望大家阅读完这篇文章之后大有收获，下面让小编带着大家一起了解一下。 1.创建数组
1.1 自动生成数组 | name | describe |
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| empty(shape[, dtype, order]) | Return a new array of given shape and type, without initializing entries. | | empty_like(a[, dtype, order, subok]) | Return a new array with the same shape and type as a given array. | | eye(N[, M, k, dtype]) | Return a 2-D array with ones on the diagonal and zeros elsewhere. | | identity(n[, dtype]) | Return the identity array. | | ones(shape[, dtype, order]) | Return a new array of given shape and type, filled with ones. | | ones_like(a[, dtype, order, subok]) | Return an array of ones with the same shape and type as a given array. | | zeros(shape[, dtype, order]) | Return a new array of given shape and type, filled with zeros. | | zeros_like(a[, dtype, order, subok]) | Return an array of zeros with the same shape and type as a given array. | | full(shape, fill_value[, dtype, order]) | Return a new array of given shape and type, filled with fill_value. | | full_like(a, fill_value[, dtype, order, subok]) | Return a full array with the same shape and type as a given array. | | arange([start,] stop[, step,][, dtype]) | Return evenly spaced values within a given interval. | | linspace(start, stop[, num, endpoint, …]) | Return evenly spaced numbers over a specified interval. | | logspace(start, stop[, num, endpoint, base, …]) | Return numbers spaced evenly on a log scale. | | geomspace(start, stop[, num, endpoint, dtype]) | Return numbers spaced evenly on a log scale (a geometric progression). | | meshgrid(*xi, **kwargs) | Return coordinate matrices from coordinate vectors. | | mgrid | nd_grid instance which returns a dense multi-dimensional “meshgrid”.) | | ogrid | nd_grid instance which returns an open multi-dimensional “meshgrid”.) |
1.2 从已有数据转化为数组 | name | describe |
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| array(object[, dtype, copy, order, subok, ndmin]) | Create an array. | | asarray(a[, dtype, order]) | Convert the input to an array. | | asanyarray(a[, dtype, order]) | Convert the input to an ndarray, but pass ndarray subclasses through. | | ascontiguousarray(a[, dtype]) | Return a contiguous array in memory (C order). | | asmatrix(data[, dtype]) | Interpret the input as a matrix. | | copy(a[, order]) | Return an array copy of the given object. | | frombuffer(buffer[, dtype, count, offset]) | Interpret a buffer as a 1-dimensional array. | | fromfile(file[, dtype, count, sep]) | Construct an array from data in a text or binary file. | | fromfunction(function, shape, **kwargs) | Construct an array by executing a function over each coordinate. | | fromiter(iterable, dtype[, count]) | Create a new 1-dimensional array from an iterable object. | | fromstring(string[, dtype, count, sep]) | A new 1-D array initialized from raw binary or text data in a string. | | loadtxt(fname[, dtype, comments, delimiter, …]) | Load data from a text file. |
2 数组属性与描述 | name | describe |
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| T | Same as self.transpose(), except that self is returned if self.ndim < 2. | | data | Python buffer object pointing to the start of the array’s data. | | dtype | Data-type of the array’s elements. | | flags | Information about the memory layout of the array. | | flat | A 1-D iterator over the array. | | imag | The imaginary part of the array. | | real | The real part of the array. | | size | Number of elements in the array. | | itemsize | Length of one array element in bytes. | | nbytes | Total bytes consumed by the elements of the array. | | ndim | Number of array dimensions. | | shape | Tuple of array dimensions. | | strides | Tuple of bytes to step in each dimension when traversing an array. | | ctypes | An object to simplify the interaction of the array with the ctypes module. | | base | Base object if memory is from some other object. |
3 数组方法与描述 | name | describe |
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| all([axis, out, keepdims]) | Returns True if all elements evaluate to True. | | any([axis, out, keepdims]) | Returns True if any of the elements of a evaluate to True. | | argmax([axis, out]) | Return indices of the maximum values along the given axis. | | argmin([axis, out]) | Return indices of the minimum values along the given axis of a. | | argpartition(kth[, axis, kind, order]) | Returns the indices that would partition this array. | | argsort([axis, kind, order]) | Returns the indices that would sort this array. | | astype(dtype[, order, casting, subok, copy]) | Copy of the array, cast to a specified type. | | byteswap(inplace) | Swap the bytes of the array elements | | choose(choices[, out, mode]) | Use an index array to construct a new array from a set of choices. | | clip([min, max, out]) | Return an array whose values are limited to [min, max]. | | compress(condition[, axis, out]) | Return selected slices of this array along given axis. | | conj() | Complex-conjugate all elements. | | conjugate() | Return the complex conjugate, element-wise. | | copy([order]) | Return a copy of the array. | | cumprod([axis, dtype, out]) | Return the cumulative product of the elements along the given axis. | | cumsum([axis, dtype, out]) | Return the cumulative sum of the elements along the given axis. | | diagonal([offset, axis1, axis2]) | Return specified diagonals. | | dot(b[, out]) | Dot product of two arrays. | | dump(file) | Dump a pickle of the array to the specified file. | | dumps() | Returns the pickle of the array as a string. | | fill(value) | Fill the array with a scalar value. | | flatten([order]) | Return a copy of the array collapsed into one dimension. | | getfield(dtype[, offset]) | Returns a field of the given array as a certain type. | | item(*args) | Copy an element of an array to a standard Python scalar and return it. | | itemset(*args) | Insert scalar into an array (scalar is cast to array’s dtype, if possible) | | max([axis, out]) | Return the maximum along a given axis. | | mean([axis, dtype, out, keepdims]) | Returns the average of the array elements along given axis. | | min([axis, out, keepdims]) | Return the minimum along a given axis. | | newbyteorder([new_order]) | Return the array with the same data viewed with a different byte order. | | nonzero() | Return the indices of the elements that are non-zero. | | partition(kth[, axis, kind, order]) | Rearranges the elements in the array in such a way that value of the element in kth position prod([axis, dtype, out, keepdims]) Return the product of the array elements over the given axis | | ptp([axis, out]) | Peak to peak (maximum - minimum) value along a given axis. | | put(indices, values[, mode]) | Set a.flat[n] = values[n] for all n in indices. | | ravel([order]) | Return a flattened array. | | repeat(repeats[, axis]) | Repeat elements of an array. | | reshape(shape[, order]) | Returns an array containing the same data with a new shape. | | resize(new_shape[, refcheck]) | Change shape and size of array in-place. | | round([decimals, out]) | Return a with each element rounded to the given number of decimals. | | searchsorted(v[, side, sorter]) | Find indices where elements of v should be inserted in a to maintain order. | | setfield(val, dtype[, offset]) | Put a value into a specified place in a field defined by a data-type. | | setflags([write, align, uic]) | Set array flags WRITEABLE, ALIGNED, and UPDATEIFCOPY, respectively. | | sort([axis, kind, order]) | Sort an array, in-place. | | squeeze([axis]) | Remove single-dimensional entries from the shape of a. | | std([axis, dtype, out, ddof, keepdims]) | Returns the standard deviation of the array elements along given axis. | | sum([axis, dtype, out, keepdims]) | Return the sum of the array elements over the given axis. | | swapaxes(axis1, axis2) | Return a view of the array with axis1 and axis2 interchanged. | | take(indices[, axis, out, mode]) | Return an array formed from the elements of a at the given indices. | | tobytes([order]) | Construct Python bytes containing the raw data bytes in the array. | | tofile(fid[, sep, format]) | Write array to a file as text or binary (default). | | tolist() | Return the array as a (possibly nested) list. | | tostring([order]) | Construct Python bytes containing the raw data bytes in the array. | | trace([offset, axis1, axis2, dtype, out]) | Return the sum along diagonals of the array. | | transpose(*axes) | Returns a view of the array with axes transposed. | | var([axis, dtype, out, ddof, keepdims]) | Returns the variance of the array elements, along given axis. | | view([dtype, type]) | New view of array with the same data. |
4 数组形态控制 | name | describe |
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| ndarray.reshape(shape[, order]) | Returns an array containing the same data with a new shape. | | ndarray.resize(new_shape[, refcheck]) | Change shape and size of array in-place. | | ndarray.transpose(*axes) | Returns a view of the array with axes transposed. | | ndarray.swapaxes(axis1, axis2) | Return a view of the array with axis1 and axis2 interchanged. | | ndarray.flatten([order]) | Return a copy of the array collapsed into one dimension. | | ndarray.ravel([order]) | Return a flattened array. | | ndarray.squeeze([axis]) | Remove single-dimensional entries from the shape of a. |
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