{ "__type": "IngestedDoc", "__tag": 4010, "_content": { "Notes": { "__type": "Section", "__tag": 4015, "children": [ { "__type": "Paragraph", "__tag": 4045, "children": [ { "__type": "Text", "__tag": 4046, "value": "While the nonzero values can be obtained with " }, { "__type": "InlineCode", "__tag": 4051, "value": "a[nonzero(a)]" }, { "__type": "Text", "__tag": 4046, "value": ", it is recommended to use " }, { "__type": "InlineCode", "__tag": 4051, "value": "x[x.astype(bool)]" }, { "__type": "Text", "__tag": 4046, "value": " or " }, { "__type": "InlineCode", "__tag": 4051, "value": "x[x != 0]" }, { "__type": "Text", "__tag": 4046, "value": " instead, which will correctly handle 0-d arrays." } ] } ], "title": [], "level": 0, "target": null }, "Warns": { "__type": "Section", "__tag": 4015, "children": [], "title": [], "level": 0, "target": null }, "Raises": { "__type": "Section", "__tag": 4015, "children": [], "title": [], "level": 0, "target": null }, "Yields": { "__type": "Section", "__tag": 4015, "children": [], "title": [], "level": 0, "target": null }, "Methods": { "__type": "Section", "__tag": 4015, "children": [], "title": [], "level": 0, "target": null }, "Returns": { "__type": "Section", "__tag": 4015, "children": [ { "__type": "Parameters", "__tag": 4026, "children": [ { "__type": "DocParam", "__tag": 4016, "name": "tuple_of_arrays", "annotation": "tuple", "desc": [ { "__type": "Paragraph", "__tag": 4045, "children": [ { "__type": "Text", "__tag": 4046, "value": "Indices of elements that are non-zero." } ] } ] } ] } ], "title": [], "level": 0, "target": null }, "Summary": { "__type": "Section", "__tag": 4015, "children": [ { "__type": "Paragraph", "__tag": 4045, "children": [ { "__type": "Text", "__tag": 4046, "value": "Return the indices of the elements that are non-zero." } ] } ], "title": [], "level": 0, "target": null }, "Receives": { "__type": "Section", "__tag": 4015, "children": [], "title": [], "level": 0, "target": null }, "Warnings": { "__type": "Section", "__tag": 4015, "children": [], "title": [], "level": 0, "target": null }, "Attributes": { "__type": "Section", "__tag": 4015, "children": [], "title": [], "level": 0, "target": null }, "Parameters": { "__type": "Section", "__tag": 4015, "children": [ { "__type": "Parameters", "__tag": 4026, "children": [ { "__type": "DocParam", "__tag": 4016, "name": "a", "annotation": "array_like", "desc": [ { "__type": "Paragraph", "__tag": 4045, "children": [ { "__type": "Text", "__tag": 4046, "value": "Input array." } ] } ] } ] } ], "title": [], "level": 0, "target": null }, "Extended Summary": { "__type": "Section", "__tag": 4015, "children": [ { "__type": "Paragraph", "__tag": 4045, "children": [ { "__type": "Text", "__tag": 4046, "value": "Returns a tuple of arrays, one for each dimension of " }, { "__type": "ParamRef", "__tag": 4071, "name": "a" }, { "__type": "Text", "__tag": 4046, "value": ", containing the indices of the non-zero elements in that dimension. The values in " }, { "__type": "ParamRef", "__tag": 4071, "name": "a" }, { "__type": "Text", "__tag": 4046, "value": " are always tested and returned in row-major, C-style order." } ] }, { "__type": "Paragraph", "__tag": 4045, "children": [ { "__type": "Text", "__tag": 4046, "value": "To group the indices by element, rather than dimension, use " }, { "__type": "InlineRole", "__tag": 4003, "value": "argwhere", "domain": null, "role": null, "inventory": null }, { "__type": "Text", "__tag": 4046, "value": ", which returns a row for each non-zero element." } ] } ], "title": [], "level": 0, "target": null }, "Other Parameters": { "__type": "Section", "__tag": 4015, "children": [], "title": [], "level": 0, "target": null } }, "_ordered_sections": [ "Summary", "Extended Summary", "Parameters", "Attributes", "Methods", "Returns", "Yields", "Receives", "Other Parameters", "Raises", "Warns", "Warnings", "Notes" ], "item_file": "/numpy/_core/fromnumeric.py", "item_line": 1993, "item_type": "_ArrayFunctionDispatcher", "aliases": [ "numpy.nonzero" ], "example_section_data": { "__type": "Section", "__tag": 4015, "children": [ { "__type": "Code", "__tag": 4050, "value": "import numpy as np\nx = np.array([[3, 0, 0], [0, 4, 0], [5, 6, 0]])\nx\nnp.nonzero(x)\n", "execution_status": "success" }, { "__type": "Text", "__tag": 4046, "value": "\n" }, { "__type": "Code", "__tag": 4050, "value": "x[np.nonzero(x)]\nnp.transpose(np.nonzero(x))\n", "execution_status": "success" }, { "__type": "Text", "__tag": 4046, "value": "\nA common use for ``nonzero`` is to find the indices of an array, where\na condition is True. Given an array `a`, the condition `a` > 3 is a\nboolean array and since False is interpreted as 0, np.nonzero(a > 3)\nyields the indices of the `a` where the condition is true.\n\n" }, { "__type": "Code", "__tag": 4050, "value": "a = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])\na > 3\nnp.nonzero(a > 3)\n", "execution_status": "success" }, { "__type": "Text", "__tag": 4046, "value": "\nUsing this result to index `a` is equivalent to using the mask directly:\n\n" }, { "__type": "Code", "__tag": 4050, "value": "a[np.nonzero(a > 3)]\na[a > 3] # prefer this spelling\n", "execution_status": "success" }, { "__type": "Text", "__tag": 4046, "value": "\n``nonzero`` can also be called as a method of the array.\n\n" }, { "__type": "Code", "__tag": 4050, "value": "(a > 3).nonzero()\n", "execution_status": "success" } ], "title": [], "level": 0, "target": null }, "see_also": [ { "__type": "SeeAlsoItem", "__tag": 4028, "name": { "__type": "CrossRef", "__tag": 4002, "value": "count_nonzero", "reference": { "__type": "RefInfo", "__tag": 4000, "module": "current-module", "version": "current-version", "kind": "to-resolve", "path": "count_nonzero" }, "kind": "module" }, "descriptions": [ { "__type": "Paragraph", "__tag": 4045, "children": [ { "__type": "Text", "__tag": 4046, "value": "Counts the number of non-zero elements in the input array." } ] } ], "type": null }, { "__type": "SeeAlsoItem", "__tag": 4028, "name": { "__type": "CrossRef", "__tag": 4002, "value": "flatnonzero", "reference": { "__type": "RefInfo", "__tag": 4000, "module": "current-module", "version": "current-version", "kind": "to-resolve", "path": "flatnonzero" }, "kind": "module" }, "descriptions": [ { "__type": "Paragraph", "__tag": 4045, "children": [ { "__type": "Text", "__tag": 4046, "value": "Return indices that are non-zero in the flattened version of the input array." } ] } ], "type": null }, { "__type": "SeeAlsoItem", "__tag": 4028, "name": { "__type": "CrossRef", "__tag": 4002, "value": "ndarray.nonzero", "reference": { "__type": "RefInfo", "__tag": 4000, "module": "current-module", "version": "current-version", "kind": "to-resolve", "path": "ndarray.nonzero" }, "kind": "module" }, "descriptions": [ { "__type": "Paragraph", "__tag": 4045, "children": [ { "__type": "Text", "__tag": 4046, "value": "Equivalent ndarray method." } ] } ], "type": null } ], "signature": { "__type": "SignatureNode", "__tag": 4029, "kind": "function", "parameters": [ { "__type": "SigParam", "__tag": 4030, "name": "a", "annotation": { "__type": "Empty", "__tag": 4031 }, "kind": "POSITIONAL_OR_KEYWORD", "default": { "__type": "Empty", "__tag": 4031 } } ], "return_annotation": { "__type": "Empty", "__tag": 4031 }, "target_name": "nonzero" }, "references": null, "qa": "numpy:nonzero", "arbitrary": [], "local_refs": [ "a", "tuple_of_arrays" ] }