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How to calculate the mean over a dataframe column with pandas in python ?

Article
Daidalos June 18, 2020

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Examples of how to calculate the mean over a dataframe column with pandas in python: [TOC] ### 1 -- Create a dataframe Lets consider the following dataframe: import pandas as pd data = {'Name':['Ben','Anna','Zoe','Tom','John','Steve'], 'Age':[20,27,43,30,12,21]} df = pd.DataFrame(data) returns Name Age 0 Ben 20 1 Anna 27 2 Zoe 43 3 Tom 30 4 John 12 5 Steve 21 ### 2 -- Calculate ...

How to replace NaN values in a pandas dataframe ?

Article
Daidalos June 17, 2020

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Examples of how to replace NaN values in a pandas dataframe [TOC] ### 1 -- Create a dataframe Lets consider the following dataframe: import pandas as pd import numpy as np data = {'Name':['Ben','Anna','Zoe','Tom','John','Steve'], 'Age':[20,27,43,30,np.nan,np.nan], 'Gender':['M',np.nan,'F','M','M','M']} df = pd.DataFrame(data) returns Name Age Gender 0 Ben 20.0 M 1 Anna 27.0 NaN 2 Zoe ...

How to convert a dataframe column of date of birth DOB to column of age with pandas in python ?

Article
Daidalos June 17, 2020

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Examples of how to convert a dataframe column of date of birth DOB to column of age with pandas in python: [TOC] ### 1 -- Create a dataframe Lets consider the following dataframe for example import pandas as pd data = {'Name':['Ben','Anna','Zoe','Tom','John','Steve'], 'dob':['1982-07-08 00:00:00', '1987-03-01 00:00:00', '2016-02-12 00:00:00', '2002-08-14 00:00:00', '2011-01-19 00: ...

How to get the age from a date of birth (DOB) in python ?

Article
Daidalos June 17, 2020

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Examples of how to get the age from a date of birth (DOB) in python: [TOC] ### 1 -- Calculate the age from a DOB (example 1) Lets consider the following date of birth: July 8, 1982: import datetime dob = datetime.date(1982,8,7) to get the age of that person at the present day (June 16, 2020), a solution is to defined a function: def from_dob_to_age(born): today = datetime.date.today() return today.year - born.year - ((today.month, today.day) < ( ...

How to remove duplicates rows in a pandas dataframe in python ?

Article
Daidalos June 16, 2020

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Examples of how to emove duplicates rows in a pandas dataframe in python: [TOC] ### 1 -- Create a dataframe Lets create first for example the following dataframe import pandas as pd data = {'Name':['Ben','Anna','Anna','Anna','Zoe','Zoe','Tom','John','Steve'], 'Age':[20,27,27,27,43,43,30,12,21], 'Sex':[1,0,0,0,0,0,1,1,1]} df = pd.DataFrame(data) print(df) returns here Name Age Sex 0 Ben 20 1 1 A ...

How to remove dataframe rows where a condition is true with pandas in python ?

Article
Daidalos June 16, 2020

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Examples of how to drop dataframe rows where a condition is true with pandas in python [TOC] ### 1 -- Create a dataframe Lets consider for example the following dataframe: >>> import pandas as pd >>> data = {'Name':['Ben','Anna','Zow','Tom','John','Steve'], 'Age':[20,27,43,30,12,21], 'Sex':[1,0,0,1,1,1]} >>> df = pd.DataFrame(data) returns here: >>> df Age Name Sex 0 20 Ben 1 1 27 Anna 0 2 43 Zoe 0 3 30 Tom 1 4 12 John ...

How to remove (filter) the duplicates in a python list ?

Article
Daidalos June 01, 2020

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Examples of how remove (filter) the duplicates in a python list: [TOC] ### 1 -- Create a list Let's consider the following list: >>> l = ['a','a','b','c','d','d','d'] the goal here is to remove the duplicates in the list. ### 2 -- Remove the duplicates using a for loop A first solution is to use a for loop, example: >>> lwd = [] >>> for i in l: ... if i not in lwd: lwd.append(i) ... >>> lwd ['a', 'b', 'c', 'd'] ### 2 -- Remove the duplicates using a d ...

How to check if an element is in a list or not in python ?

Article
Daidalos June 01, 2020

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Examples of how to check if an element is in a list or not in python: [TOC] ### 1 -- Create a liste Lets create for instance the following list: >>> l ['a', 'b', 'c', 'd', 'e', 'f'] ### 2 -- Check if an element is in the list To check if the element 'c' is in the list called here l, a solution is to use the following logical expression: >>> 'c' in l True check now if 'g' is in the list >>> 'g' in l returns here: False Can then be used with if, illustra ...

How to get a list of names (variables) of data stored in a HDF5 file using pandas in python ?

Article
Daidalos May 27, 2020

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Example of how to get a list of names (variables) of data stored in a HDF5 file using pandas in python [TOC] ### 1 -- Read the file First, to read an HDF5 file using pandas, we can do: store = pd.HDFStore('data.hdf5') or with pd.HDFStore('data.hdf5') as store: ... ... ### 2-- Get a list of names (variables) of data stored in a HDF5 file using pandas To get the name of all data stored in the hdf5 file, a solution is to use keys() : sto ...

How to find in a list the elements starting by *** in python ?

Article
Daidalos May 26, 2020

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Example of how to find in a list the elements starting by *** in python: [TOC] ### 1 - - Create a simple list in python Lets create a liste with words: l = ['name', 'address_01', 'address_02', 'address_03', 'job', 'income'] ### 2 - - Select words that starts by *** For example, lets select only the words that start by 'address' using a list comprehension and the python method [startswith()](https://www.tutorialspoint.com/python/string_startswith.htm): sub_l = [i for ...

How to find the smallest positive value in a list in python

Article
Daidalos May 26, 2020

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Examples of how to find the smallest positive value in a list in python ? [TOC] ### 1 -- Find the minimum value Let's consider the following list l = [ 7, 3, 6, 9, 2, -1, -5, -4, -3] to find the smallest value, a solution is to use the function min(): min(l) which returns here: -1 ### 2 -- Find the smallest positive value Now to find the smallest positive value a solution is to use a list comprehension and then min(): min([i for i in l if i > 0]) ...

How to find the difference in minutes between two dates in python ?

Article
Daidalos May 26, 2020

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Examples of how to find the difference in minutes between two dates in python: [TOC] ### 1 -- Create two dates Let's create two dates objects in python using the module datetime: import datetime year = 2008 month = 7 day = 8 hour = 12 minute = 47 second = 0 time1 = datetime.datetime(year,month,day,hour,minute,second) hour = 14 minute = 20 time2 = datetime.datetime(year,month,day,hour,minute,second) ### 2 -- Example 1 u ...

How to select randomly (sample) the rows of a dataframe using pandas in python ?

Article
Daidalos May 24, 2020

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Example of how to select randomly (sample) the rows of a dataframe using pandas in python: [TOC] ### 1 -- Create a simple dataframe Créons une simple dataframe avec 5 colonnes et 20 lignes: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,101) >>> data = data.reshape(20,5) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d','e']) >>> df a b c d e 0 1 2 3 4 5 1 6 7 8 9 10 2 11 12 13 14 15 3 16 ...

How to edit a pandas dataframe column values where a condition is verified in python ?

Article
Daidalos May 24, 2020

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Examples of how to edit a pandas dataframe column values where a condition is verified in python: [TOC] ### 1 -- Create a simple dataframe with pandas Lets' start by creating a simple dataframe with 5 columns and 20 rows: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,101) >>> data = data.reshape(20,5) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d','e']) returns >>> df a b c d e 0 1 2 3 4 5 1 6 7 8 ...

How to select dataframe rows using a condition with pandas in python ?

Article
Daidalos May 24, 2020

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Examples of how to select a dataframe rows using a condition with pandas in python: [TOC] ### 1 -- Create a simple dataframe Lets start by creating a simple dataframe with pandas: >>> import pandas as pd >>> data = {'Name':['Ben','Anna','Zow','Tom','John','Steve'], 'Age':[20,27,43,30,12,21], 'Sex':[1,0,0,1,1,1]} >>> df = pd.DataFrame(data) returns >>> df Age Name Sex 0 20 Ben 1 1 27 Anna 0 2 43 Zow 0 3 30 Tom 1 4 12 Joh ...

How to select dataframe columns that start with *** using pandas in python ?

Article
Daidalos May 24, 2020

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Examples of how to select dataframe columns that start with *** using pandas in python: [TOC] ### 1 -- Create a dataframe Lets start by creating a simple dataframe with 8 columns: import pandas as pd import numpy as np data = np.arange(1,33) data = data.reshape(4,8) df = pd.DataFrame(data=data,columns=['name','add_01','add_02','add_03', 'counrty','streed','zip code','county']) print(df) returns name ...

How to calculate and plot a cumulative distribution function with matplotlib in python ?

Article
Daidalos May 10, 2020

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Examples of how to calculate and plot a cumulative distribution function in python [TOC] ### 1 -- Generate random numbers Let's for example generate random numbers from a normal distribution: import numpy as np import matplotlib.pyplot as plt N = 100000 data = np.random.randn(N) ### 2 -- Create an histogram with matplotlib hx, hy, _ = plt.hist(data, bins=50, normed=1,color="lightblue") plt.ylim(0.0,max(hx)+0.05) plt.title('Generate random numbers \n from a ...

How to calculate a log-likelihood in python (example with a normal distribution) ?

Article
Daidalos May 10, 2020

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Example of how to calculate a log-likelihood using a normal distribution in python: [TOC] See the note: [How to estimate the mean with a truncated dataset using python ?](https://www.science-emergence.com/Articles/How-to-estimate-the-mean-with-a-truncated-dataset-using-python-/) to understand the interest of calculating a log-likelihood using a normal distribution in python. ### 1 -- Generate random numbers from a normal distribution Let's for example create a sample of 100000 rando ...

How to add text (units, %, etc) in a heatmap cell annotations using seaborn in python ?

Article
Daidalos May 09, 2020

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Example of how to add text (units, %, etc) in a heatmap cell annotations using seaborn in python: [TOC] ### 1 -- Create a simple heatmap with seaborn Let's create a heatmap with seaborn: import seaborn as sns import numpy as np import pandas as pd import matplotlib.pyplot as plt data = np.array([[25.55535942, 1.99598017, 9.78107706], [ 4.95758736, 39.68268716, 16.78109873], [ 0.45401194, 0.10003128, 0.6921669 ]]) df = pd.DataFrame(data=data) fig = plt.fig ...

How to estimate the mean with a truncated dataset using python ?

Article
Daidalos May 09, 2020

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Examples of how to estimate the mean with a truncated dataset using python for data generated from a normal distribution: [TOC] ### 1 -- Create a dataset of random numbers from a normal distribution Create a set of random numbers distributed according to a normal distribution: import scipy.stats import numpy as np import matplotlib.pyplot as plt mu_0 = 2.0 srd_0 = 4.0 data = np.random.randn(100000) data = data * srd_0 + mu_0 data = data.reshape(-1, 1) ### 2 -- ...

How to use a Gaussian mixture model (GMM) with sklearn in python ?

Article
Daidalos May 09, 2020

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Examples of how to use a Gaussian mixture model (GMM) with sklearn in python: [TOC] from sklearn import mixture import numpy as np import matplotlib.pyplot as plt ### 1 -- Example with one Gaussian Let's generate random numbers from a normal distribution with a mean $\mu_0 = 5$ and standard deviation $\sigma_0 = 2$ mu_0 = 5.0 srd_0 = 2.0 data = np.random.randn(100000) data = data * srd_0 + mu_0 data = data.reshape(-1, 1) Plot the data ...

How to generate random numbers from a log-normal distribution in python ?

Article
Daidalos May 09, 2020

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Example of how to generate random numbers from a log-normal distribution in python ? [TOC] Log-normal distribution: \begin{equation} \frac{1}{x \sigma \sqrt{2\pi}}.exp(-\frac{(len(x)-\mu)^2}{2\sigma^2}) \end{equation} ### 2 -- Using scipy lognorm Example of how to generate random numbers from a log-normal distribution with $\mu=0$ and $\sigma=0.5$ using scipty function lognorm: from scipy.stats import lognorm import numpy as np import matplotlib.pyplot as plt st ...

How to add text on an image using pillow in python ?

Article
Daidalos May 09, 2020

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Example of how to add text on an image using pillow in python: [TOC] ### 1 -- Create an image with pillow and add text on it Example 1: let's for example create a simple image with a red background: from PIL import Image img = Image.new('RGB', (600, 400), color = 'red') img.save('pil_red.png') [image:pilred02 size:50 caption:How to add text on an image using pillow in python ?] To add text, you must first download a 'font' file locally to your machine, for example f ...

How to increase the size of the cells text (annotations) of a seaborn heatmap in python ?

Article
Daidalos May 09, 2020

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Example of how to increase the size of the cells text (annotations) of a seaborn heatmap in python: [TOC] ### 1 -- Create a simple heatmap using seaborn Let's first create a simple heatmap using seaborn: import seaborn as sns import numpy as np import pandas as pd import matplotlib.pyplot as plt data = np.array([[25.55535942, 1.99598017, 9.78107706], [ 4.95758736, 39.68268716, 16.78109873], [ 0.45401194, 0.10003128, 0.6921669 ]]) df = pd.DataFrame(data=data ...

How to increase the size of axes labels on a seaborn heatmap in python ?

Article
Daidalos May 09, 2020

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Examples of how to increase the size of axes labels on a seaborn heatmap in python: [TOC] ### 1 -- Create a simple heatmap using seaborn Let's create a first simple heatmap using seaborn: import seaborn as sns import numpy as np import pandas as pd import matplotlib.pyplot as plt data = np.array([[25.55535942, 1.99598017, 9.78107706], [ 4.95758736, 39.68268716, 16.78109873], [ 0.45401194, 0.10003128, 0.6921669 ]]) df = pd.DataFrame(data=data,columns=['C1',' ...

How to remove lines from a to b in a text file using the editor vi ?

Article
Daidalos May 08, 2020

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Example of how to remove lines from a to b using vi editor ? [TOC] ### 1 -- Remove lines from a to b (with b>a) To delete lines from a to b, a solution is to use the command: :m,nd Note: to remove from the current line to line n: :,nd ### 2 -- Remove all lines Note: to remove all content in the file: :1,$d ### 3 -- References - [Delete from the current cursor position to a given line number in vi editor](https://stackoverflow.com/questions/6384561/d ...

How to calculate a Gaussian density probability function at a given point in python ?

Article
Daidalos April 30, 2020

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Let's consider the normal (Gaussian) distribution with mean equal to 8 and standard deviation equal to 2: [image:probability-normal-distribution size:75 caption:How to calculate a Gaussian density probability function at a given point in python ?] To calculate a Gaussian density probability function at a given point in python, a solution is to do: scipy.stats.norm.pdf(6,8,2) returns: 0.13 Source code to create the plot: import matplotlib.pyplot as plt import sc ...

How to create a global variable in python ?

Article
Daidalos April 29, 2020

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Example of how to create a global variable in python: [TOC] ### 1 -- Using global To declare for example a as a global variable: global a ### 2 -- Illustration with a function Using global variables in a function: >>> global a,b >>> a = 0.5 >>> b = 2 >>> def function( x ): ... return a * x + b ... >>> function(1) 2.5 >>> b = 4 >>> function(1) 4.5 ### 3 -- References - [Python function global variab ...

How to multiply two complex numbers in python ?

Article
Daidalos April 15, 2020

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Example of how to multiply two complex numbers in python [TOC] ### Create two complex numbers in python Let's import the module python cmath that is used to work with complex numbers >>> import cmath Create a first complex number z1: >>> z1 = 1.0 + 2.0j >>> z1 (1+2j) of real part >>> z1.real 1.0 and imaginary part >>> z1.imag 2.0 Let's also create another complex number z2: >>> z2 = 3.0 + 5.0j >>> z2 (3+5j) ...

How to create an empty data frame with pandas and add new entries row by row ?

Article
Daidalos April 15, 2020

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Example of how to create an empty data frame with pandas and add new entries row by row in python: [TOC] ### Create an empty data frame Let's create an empty data frame with pandas: >>> import pandas as pd >>> df1 = pd.DataFrame(columns=['a','b','c','d']) >>> df1 Empty DataFrame Columns: [a, b, c, d] Index: [] Check the number of rows: >>> len(df1) 0 Check the number of columns: >>> len(df1.columns) 4 ### Add new row with ...

How to count the number of occurrences of elements in a pandas data frame column in python ?

Article
Daidalos April 15, 2020

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Examples of how to count the number of occurrences of elements in a pandas data frame column in python [TOC] ### Create a simple date frame with pandas Let's create a simple data frame called df: >>> import pandas as pd >>> import numpy as np >>> df = pd.DataFrame(columns=['target','a','b']) >>> df = df.append({"target": 0, "a": "no", "b": "M"}, ignore_index=True) >>> df = df.append({"target": 1, "a": "yes", "b": "F"}, ignore_index=True) >>> df = df.append({"target ...

How to add a frame to a seaborn heatmap figure in python ?

Article
Daidalos April 15, 2020

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Example of how to add a frame to a seaborn heatmap figure in python [TOC] ### Plot a figure with seaborn heatmap Example of how to plot a figure with seaborn heatmap import seaborn as sns import numpy as np import pandas as pd import matplotlib.pyplot as plt data = np.array([[25.55535942, 1.99598017, 9.78107706], [ 4.95758736, 39.68268716, 16.78109873], [ 0.45401194, 0.10003128, 0.6921669 ]]) df = pd.DataFrame(data=data) fig = plt.figure(num=None, figsi ...

How to change the colorbar size of a seaborn heatmap figure in python ?

Article
Daidalos April 15, 2020

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Example of how to change the colorbar size of a seaborn heatmap figure in python: [TOC] ### Create a seaborn heatmap figure import seaborn as sns import numpy as np import pandas as pd import matplotlib.pyplot as plt data = np.array([[25.55535942, 1.99598017, 9.78107706], [ 4.95758736, 39.68268716, 16.78109873], [ 0.45401194, 0.10003128, 0.6921669 ]]) df = pd.DataFrame(data=data) fig = plt.figure(num=None, figsize=(10, 10), dpi=80, facecolor='w', edgecol ...

How to check if a directory exists in python ?

Article
Daidalos April 15, 2020

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Example of how to check if a directory exists in python: [TOC] ### Using the os function isdir() To check if a file (called for example "images") exists, a solution in python is to use the function [isdir](https://docs.python.org/3/library/os.path.html#os.path.isdir) : >>> import os >>> os.path.isdir('images') that returns a boolean (True or False) is the directory 'images' exists or not. = To test if the directory is available with the path /users/john/images: ...

How to check if a file exists in python ?

Article
Daidalos April 15, 2020

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Example of how to check if a file exists in python: [TOC] ### Using the os function isfile() To check if a file (called for example "photo_001.png") exists, a solution in python is to use the function[isfile](https://docs.python.org/3/library/os.path.html#os.path.isfile): >>> import os >>> os.path.isfile('photo_001.png') that returns a boolean (True or False) is the file 'photo_001.png' exists or not. = To test if the file is available with the path /users/john/photo ...

How to create a table of contents in a jupyter notebook ?

Article
Daidalos April 14, 2020

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Example of how to create a table of contents in a jupyter notebook [TOC] ### Create a table of contents To start, lets create two markdown cells (see image below) [image:jupyter-notebook-toc-01 size:75 caption:How to create a table of contents in a jupyter notebook ?] then, to create a table of contents, a solution is to create a markdown link to an anchor: ### Table of Contents * [Chapter 1](#chapter1) * [Section 1.1](#section_1_1) * [Section 1.2](sSection_1_2) ...

How to center a matplotlib figure in a Jupyter notebook ?

Article
Daidalos April 14, 2020

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Example of how to center a matplotlib figure in a Jupyter notebook: [TOC] ### Plot a matplotlib figure in a Jupyter notebook Let's create a simple matplotlib figure: import matplotlib.pyplot as plt plt.scatter([1,2,3,4,5,6,7,8],[4,1,3,6,1,3,5,2]) plt.title('Nuage de points avec Matplotlib') plt.xlabel('x') plt.ylabel('y') To show the figure in the Jupyter notebook just add: plt.show() by default will be align on the left: [image:jupyter-not ...

How to generate a random number between 0 and 1 in python ?

Article
Daidalos April 14, 2020

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Examples of how to generate a random number between 0 and 1 in python [TOC] ### Using function random.uniform() To generate a random number between 0 and 1, there are several solutions for example using the random module with uniform(): >>> import random >>> x = random.uniform(0,1) >>> x 0.24773029475050623 Generate a list of random numbers between 0 and 1: >>> list_rx = [random.uniform(0,1) for i in range(10000)] and plot: >>> import matplotlib ...

How to divide by a number the elements of a pandas data frame column in python ?

Article
Daidalos April 14, 2020

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Example of how to divide by a number the elements of a pandas data frame column in python ? [TOC] ### Create a simple Data frame Let's create a data frame with pandas called df: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,13) >>> data = data.reshape(3,4) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d']) >>> df a b c d 0 1 2 3 4 1 5 6 7 8 2 9 10 11 12 ### Divide by a number the elements of a given colu ...

How to subtract by a number the elements of a datafame column with pandas in python ?

Article
Daidalos April 14, 2020

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Example of how to subtract by a number the elements of a datafame column with pandas in python: [TOC] ### Create a simple Data frame Let's create a data frame with pandas called df: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,13) >>> data = data.reshape(3,4) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d']) >>> df a b c d 0 1 2 3 4 1 5 6 7 8 2 9 10 11 12 ### Subtract by a number the elements of a give ...

How to multiply by a number the elements of a DataFrame column with pandas in python ?

Article
Daidalos April 14, 2020

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Example of how to multiply by a number the elements of a DataFrame column with pandas in python [TOC] ### Create a simple Data frame Let's create a data frame with pandas called df: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,13) >>> data = data.reshape(3,4) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d']) >>> df a b c d 0 1 2 3 4 1 5 6 7 8 2 9 10 11 12 ### Multiply by a number the elements of a give ...

How to add a constant number to a DataFrame column with pandas in python ?

Article
Daidalos April 14, 2020

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Example of how to add a constant number to a DataFrame column with pandas in python [TOC] ### Create a simple Data frame Let's create a data frame with pandas called df: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,13) >>> data = data.reshape(3,4) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d']) >>> df a b c d 0 1 2 3 4 1 5 6 7 8 2 9 10 11 12 ### Add a constant number to each column elements Let's ...

How to merge / concatenate two DataFrames with pandas in python ?

Article
Daidalos April 14, 2020

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Basic examples of how to merge / concatenate two DataFrames with pandas in python: [TOC] ### Create two data frames Let's create a first data frame called df1 with pandas >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,13) >>> data = data.reshape(3,4) >>> df1 = pd.DataFrame(data=data,columns=['a','b','c','d']) >>> df1 a b c d 0 1 2 3 4 1 5 6 7 8 2 9 10 11 12 Create a second data frame df2 >>> df2 = pd.DataFram ...

How to solve a quadratic equation in python using numpy ?

Article
Daidalos April 11, 2020

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Examples of how to solve a quadratic degree equation in python using numpy: [TOC] ### Example 1 With python we can find the roots of a polynomial equation of degree 2 ($ ax ^ 2 + bx + c $) using the function numpy: [roots](http://docs.scipy.org/doc/numpy/reference/generated/numpy.roots.html#numpy-roots). Consider for example the following polynomial equation of degree 2 $ x ^ 2 + 3x-0 $ with the coefficients $ a = 1 $, $ b = 3 $ and $ c = -4 $, we then find: >>> import nump ...

How to get the number of columns in a pandas DataFrame in python ?

Article
Daidalos April 11, 2020

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Example of how to get the number of columns in a pandas DataFrame in python: [TOC] ### Create a simple dataframe with pandas Let's start by creating a simple dataframe df: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,13) >>> data = data.reshape(3,4) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d']) >>> df a b c d 0 1 2 3 4 1 5 6 7 8 2 9 10 11 12 ### Get the number of columns To obtain the number of ...

How to get the number of rows in a pandas DataFrame in python ?

Article
Daidalos April 11, 2020

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Example of how to get the number of rows in a pandas DataFrame in python: [TOC] ### Create a simple dataframe with pandas Let's start by creating a simple dataframe df: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,13) >>> data = data.reshape(3,4) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d']) >>> df a b c d 0 1 2 3 4 1 5 6 7 8 2 9 10 11 12 ### Get the number of rows To obtain the number of rows o ...

How to add a column to a pandas DataFrame in python ?

Article
Daidalos April 11, 2020

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Example of how to add a column to a pandas DataFrame in python: [TOC] ### Create a simple dataframe with pandas Let's start by creating a simple dataframe df: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,13) >>> data = data.reshape(3,4) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d']) >>> df a b c d 0 1 2 3 4 1 5 6 7 8 2 9 10 11 12 ### Add a column to a dataframe dataframe To add a column we can ...

How to add a new row at the end of a pandas DataFrame in pandas ?

Article
Daidalos April 11, 2020

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Example of how to add a new row at the end of a pandas DataFrame in pandas [TOC] ### Create a simple dataframe with pandas Let's start by creating a simple dataframe df: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,13) >>> data = data.reshape(3,4) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d']) >>> df a b c d 0 1 2 3 4 1 5 6 7 8 2 9 10 11 12 ### Add a row to a dataframe To add a line to the df dat ...

How to apply a function to a DataFrame row with pandas in python ?

Article
Daidalos April 11, 2020

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Example of how to apply a function to a DataFrame row with pandas in python: [TOC] ### Create a simple dataframe with pandas Let's start by creating a simple dataframe df: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,13) >>> data = data.reshape(3,4) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d']) >>> df a b c d 0 1 2 3 4 1 5 6 7 8 2 9 10 11 12 ### Apply a function on a given row So let's try to mo ...

How to apply a function to a DataFrame column with pandas in python ?

Article
Daidalos April 11, 2020

Creative Commons License

Example of how to apply a function to a DataFrame column with pandas in python: [TOC] ### Create a simple dataframe with pandas Let's start by creating a simple dataframe df: >>> import pandas as pd >>> import numpy as np >>> data = np.arange(1,13) >>> data = data.reshape(3,4) >>> df = pd.DataFrame(data=data,columns=['a','b','c','d']) >>> df a b c d 0 1 2 3 4 1 5 6 7 8 2 9 10 11 12 ### Apply a function on a given column So let's try ...

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