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learnp
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update nditer tutorial
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‎numpy/nditer.ipynb

+172-22
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@@ -1,8 +1,15 @@
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{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<h1 style=\"color:green\" align='center'>Numpy tutorial: iterate numpy array using nditer</h1>"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 1,
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"execution_count": 27,
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"metadata": {
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"collapsed": true
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},
@@ -13,8 +20,10 @@
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},
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{
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"cell_type": "code",
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"execution_count": 26,
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"metadata": {},
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"execution_count": 28,
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"metadata": {
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"scrolled": true
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},
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"outputs": [
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{
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"data": {
@@ -24,7 +33,7 @@
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" [ 8, 9, 10, 11]])"
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]
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},
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"execution_count": 26,
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"execution_count": 28,
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"metadata": {},
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"output_type": "execute_result"
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}
@@ -38,12 +47,94 @@
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<h2 style=\"color:purple\">C style ordering</h2>"
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"<h3 style=\"color:purple\">Using normal for loop iteration</h3>"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 27,
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"execution_count": 29,
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"metadata": {
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"scrolled": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"0\n",
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"1\n",
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"2\n",
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"3\n",
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"4\n",
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"5\n",
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"8\n",
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"9\n",
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"10\n",
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"11\n"
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]
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}
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],
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"source": [
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"for row in a:\n",
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" for cell in row:\n",
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" print(cell)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<h3 style=\"color:purple\">For loop with flatten</h3>"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 30,
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"metadata": {},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"0\n",
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"9\n",
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"10\n",
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"11\n"
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]
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}
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],
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"source": [
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"for cell in a.flatten():\n",
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" print(cell)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<h1 style=\"color:blue\" align=\"center\">nditer</h1>"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<h3 style=\"color:purple\">C style ordering</h3>"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 31,
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"metadata": {
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"scrolled": true
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},
@@ -81,9 +172,9 @@
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},
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{
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"cell_type": "code",
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"execution_count": 28,
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"execution_count": 32,
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"metadata": {
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"scrolled": true
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"scrolled": false
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},
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"outputs": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<h2 style=\"color:purple\">Modify array values while iterating</h2>"
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"<h3 style=\"color:purple\">external_loop</h3>"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 33,
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"metadata": {
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"scrolled": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"[0 4 8]\n",
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"[1 5 9]\n",
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"[ 2 6 10]\n",
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"[ 3 7 11]\n"
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]
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}
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],
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"source": [
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"for x in np.nditer(a, flags=['external_loop'],order='F'):\n",
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" print(x)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<h2 style=\"color:purple\">Modify array values while iterating</h2>"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 34,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"for x in np.nditer(a, op_flags=['readwrite']):\n",
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" x[...] = x + 1"
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" x[...] = x * x"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 34,
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"execution_count": 35,
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"metadata": {
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"scrolled": true
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},
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"outputs": [
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{
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"data": {
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"text/plain": [
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"array([[ 1, 2, 3, 4],\n",
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" [ 5, 6, 7, 8],\n",
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" [ 9, 10, 11, 12]])"
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"array([[ 0, 1, 4, 9],\n",
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" [ 16, 25, 36, 49],\n",
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" [ 64, 81, 100, 121]])"
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]
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},
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"execution_count": 34,
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"execution_count": 35,
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"metadata": {},
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"output_type": "execute_result"
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}
@@ -162,26 +283,55 @@
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},
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{
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"cell_type": "code",
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"execution_count": 35,
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"execution_count": 36,
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"metadata": {},
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"outputs": [
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{
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"data": {
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"text/plain": [
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"array([[ 0, 1, 2, 3],\n",
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" [ 4, 5, 6, 7],\n",
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" [ 8, 9, 10, 11]])"
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"array([[ 3],\n",
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" [ 7],\n",
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" [11]])"
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]
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},
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"execution_count": 35,
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"execution_count": 36,
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"metadata": {},
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"output_type": "execute_result"
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}
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],
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"source": [
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"b = np.arange(12).reshape(3,4)\n",
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"b = np.arange(3, 15, 4).reshape(3,1)\n",
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"b"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 37,
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"metadata": {},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"0 3\n",
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"1 3\n",
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"4 3\n",
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"9 3\n",
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"16 7\n",
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"64 11\n",
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"121 11\n"
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]
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}
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],
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"source": [
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"for x, y in np.nditer([a,b]):\n",
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" print (x,y)"
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]
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}
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],
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"metadata": {
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.6.1"
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"version": "3.6.3"
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}
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},
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"nbformat": 4,

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