Programming Articles - Page 1108 of 3363

To rename columns in a Pandas DataFrame, we can override df.columns with the new column names.StepsCreate a two-dimensional, size-mutable, potentially heterogeneous tabular data, df.Print the input DataFrame.Override the columns with new list of column names.Print the DataFrame again with the renamed column names.Example Live Demoimport pandas as pd df = pd.DataFrame(    {       "x": [5, 2, 1, 9],       "y": [4, 1, 5, 10],       "z": [4, 1, 5, 0]    } ) print("Input DataFrame is:", df) df.columns = ["a", "b", "c"] print("After renaming, DataFrame is:", df)OutputInput DataFrame is:    x  y  z 0  5  4  4 1  2  1  1 2  1  5  5 3  9 10  0 After renaming, DataFrame is:    a  b  c 0  5  4  4 1  2  1  1 2  1  5  5 3  9 10  0

To select rows from a DataFrame based on column values, we can take the following Steps −Create a two-dimensional, size-mutable, potentially heterogeneous tabular data, df.Print the input DataFrame.Use df.loc[df["x"]==2] to print the DataFrame when x==2.Similarly, print the DataFrame when (x >= 2) and (x < 2).Example Live Demoimport pandas as pd df = pd.DataFrame(    {       "x": [5, 2, 1, 9],       "y": [4, 1, 5, 10],       "z": [4, 1, 5, 0]    } ) print "Given DataFrame is:", df print "When column x value == 2:", df.loc[df["x"] == 2] ... Read More

To iterate rows in a DataFrame in Pandas, we can use the iterrows() method, which will iterate over DataFrame rows as (index, Series) pairs.StepsCreate a two-dimensional, size-mutable, potentially heterogeneous tabular data, df.Iterate df using df.iterrows() method.Print each row with index.Example Live Demoimport pandas as pd df = pd.DataFrame(    {       "x": [5, 2, 1, 9],       "y": [4, 1, 5, 10],       "z": [4, 1, 5, 0]    } ) print "Given DataFrame:", df for index, row in df.iterrows():    print "Row ", index, "contains: "    print row["x"], row["y"], row["z"]OutputGiven DataFrame:    x   y   z 0  5   4   4 1  2   1   1 2  1   5   5 3  9  10   0 Row 0 contains: 5 4 4 Row 1 contains: 2 1 1 Row 2 contains: 1 5 5 Row 3 contains: 9 10 0

Find index of mid element (minimum element) Apply Binary Search on the subarray based on following conditions −If number lies between start element and element at mid1 position.Then find number in array start to mid-1 using binary searchElse if number lies between mid and last element, then find number in array mid to last element using binary search.Example Live Demousing System; using System.Collections.Generic; using System.Text; using System.Linq; namespace ConsoleApplication{    public class Arrays{       public int FindNumberRotated(int[] array, int start, int end, int value){          if (start > end){             return ... Read More

We have to make the knight cover all the cells of the board and it can move to a cell only once.There can be two ways of finishing the knight move - the first in which the knight is one knight's move away from the cell from where it began, so it can go to the position from where it started and form a loop, this is called closed tour, the second in which the knight finishes anywhere else, this is called open tour. A move is valid if it is inside the chessboard and if the cell is not ... Read More

Create a backtrack function that updates the current string if open brackets are less than n or close bracket are less than open bracket. When the length of current string becomes equal to 2*n, add it to the combination result array. It could be simply tracked by keeping the number of { } placed . We can start an opening bracket if we still have one left to place. And we can start a closing bracket if it would not exceed the number of opening brackets.Example Live Demousing System; using System.Collections.Generic; using System.Text; using System.Linq; namespace ConsoleApplication{    public class BackTracking{ ... Read More

Create an output list to store the valid sequences, create a current list that will store the current sequence found in the path of the recursion tree. A backtrack function that will go into the recursion until the target is achieved, otherwise, it should backtrack to the previous phase as target becomes less than 0. At any point in time, if target becomes 0 then add the candidate array to the result as the values in the candidate array must be sum up to the given target.If those are not the cases then, one by one add the elements in ... Read More

Create an output list to store the valid sequences, create a current list that will store the current sequence found in the path of the recursion tree. A backtrack function that will go into the recursion until the target is achieved, otherwise, it should backtrack to the previous phase as target becomes less than 0. At any point in time, if target becomes 0 then add the candidate array to the result as the values in the candidate array must be sum up to the given target.If those are not the cases then, one by one add the elements in ... Read More

Distinct subsets problem gives us the different combination from the given array.When the target is 2 then from the array, we take all the combination that corresponds to number 2, When the target is three then from the array, we take all the combination that corresponds to count 3. In the below example the array is [1, 2, 3] and the target is 2. So, we take all the combinations the corresponds to number 2 “1, 2 “, “2, 3”, ”1, 3””.Example Live Demousing System; using System.Collections.Generic; using System.Text; using System.Linq; namespace ConsoleApplication{    public class BackTracking{       public ... Read More

Target sum problem is the problem of finding a subset such that the sum of elements equal a given number. The backtracking approach generates all permutations in the worst case but in general, performs better than the recursive approach towards subset sum problem.A subset A of n positive integers and a value sum is given, find whether or not there exists any subset of the given set, the sum of whose elements is equal to the given value of sumSuppose we have an array [1, 2, 3] the output will be “1, 1, 1, 1 “, “1, 1, 2”, ”2, ... Read More