I trust you are doing well. I am using a data frame in which there are two columns screens and it's frequency. I am trying to find out the relationship between the screen and the frequency of the appearance of the screens. Now I want to know, for all screens what are all of the frequencies as sort of a summary graph. Imagine putting all of those frequencies into an array, and wanting to study the distribution in that array. Below is my code that I have tried so far:
data = pd.read_csv('frequency_list.csv')
new_columns = data.columns.values
new_columns[1] = 'frequency'
data.columns = new_columns
import matplotlib.pyplot as plt
%matplotlib inline
dataset = data.head(10)
dataset.plot(x = "screen", y = "frequency", kind = "bar")
plt.show()
col_one_list = unpickled_df['screen'].tolist()
col_one_arr = unpickled_df['screen'].head(10).to_numpy()
plt.hist(col_one_arr) #gives you a histogram of your array 'a'
plt.show() #finishes out the plot
Below is the screenshot of my data frame containing screen as one column and frequency as another. Can you help me to find out a way to plot a frequency distribution graph? Thanks in advance.
Will a bar plot work? Here's an example:
import pandas as pd
import matplotlib.pyplot as plt
freq = [102,98,56,117]
screen = ['A','B','C','D']
df = pd.DataFrame(list(zip(screen, freq)), columns=['screen', 'freq'])
plt.bar(df.screen,df.freq)
plt.xlabel('x')
plt.ylabel('count')
plt.show()
Related
Am trying to find hist()'s figsize and layout parameter for sns.pairplot().
I have a pairplot that gives me nice scatterplots between the X's and y. However, it is oriented horizontally and there is no equivalent layout parameter to make them vertical to my knowledge. 4 plots per row would be great.
This is my current sns.pairplot():
sns.pairplot(X_train,
x_vars = X_train.select_dtypes(exclude=['object']).columns,
y_vars = ["SalePrice"])
This is what I would like it to look like: Source
num_mask = train_df.dtypes != object
num_cols = train_df.loc[:, num_mask[num_mask == True].keys()]
num_cols.hist(figsize = (30,15), layout = (4,10))
plt.show()
What you want to achieve isn't currently supported by sns.pairplot, but you can use one of the other figure-level functions (sns.displot, sns.catplot, ...). sns.lmplot creates a grid of scatter plots. For this to work, the dataframe needs to be in "long form".
Here is a simple example. sns.lmplot has parameters to leave out the regression line (fit_reg=False), to set the height of the individual subplots (height=...), to set its aspect ratio (aspect=..., where the subplot width will be height times aspect ratio), and many more. If all y ranges are similar, you can use the default sharey=True.
import matplotlib.pyplot as plt
import seaborn as sns
import pandas as pd
import numpy as np
# create some test data with different y-ranges
np.random.seed(20230209)
X_train = pd.DataFrame({"".join(np.random.choice([*'uvwxyz'], np.random.randint(3, 8))):
np.random.randn(100).cumsum() + np.random.randint(100, 1000) for _ in range(10)})
X_train['SalePrice'] = np.random.randint(10000, 100000, 100)
# convert the dataframe to long form
# 'SalePrice' will get excluded automatically via `melt`
compare_columns = X_train.select_dtypes(exclude=['object']).columns
long_df = X_train.melt(id_vars='SalePrice', value_vars=compare_columns)
# create a grid of scatter plots
g = sns.lmplot(data=long_df, x='SalePrice', y='value', col='variable', col_wrap=4, sharey=False)
g.set(ylabel='')
plt.show()
Here is another example, with histograms of the mpg dataset:
import matplotlib.pyplot as plt
import seaborn as sns
mpg = sns.load_dataset('mpg')
compare_columns = mpg.select_dtypes(exclude=['object']).columns
mpg_long = mpg.melt(value_vars=compare_columns)
g = sns.displot(data=mpg_long, kde=True, x='value', common_bins=False, col='variable', col_wrap=4, color='crimson',
facet_kws={'sharex': False, 'sharey': False})
g.set(xlabel='')
plt.show()
I'd like to add text beneath a plot, which includes the source of the used data.
It should be positioned at the edge of the image, so beneath the longest ytick and if possible at a fixed vertical distance to the x-axis.
My approach:
import matplotlib.pyplot as plt
country = ['Portugal','Spain','Austria','Italy','France','Federal Republic of Germany']
value = [6,8,10,12,14,25]
plt.figure(figsize=(4,4))
plt.barh(country,value)
plt.xlabel('x-axis')
plt.text(-18,-2.5,'Source: blablablablablablablablablablablablablablablablabla',ha='left')
Plot of the code
I used plt.text(). My problem with the command is, that I have to manually try x and y values (in the code: -18,-2.5) for different plots.
Is there a better way?
Thanks in advance.
Firstly, I got the box info of yticklabels, and then got the leftmost x location for all the yticklabels. Finally, the blended transform method was used to add text with some location adjustments.
import matplotlib.pyplot as plt
from matplotlib.transforms import IdentityTransform
import matplotlib.transforms as transforms
country = ['Portugal','Spain','Austria','Italy','France','Federal Republic of Germany']
value = [6,8,10,12,14,25]
plt.figure(figsize=(4,4))
plt.barh(country,value)
plt.xlabel('x-axis')
ax = plt.gca()
fig =plt.gcf()
fig.tight_layout()
fig.canvas.draw()
labs = ax.get_yticklabels()
xlocs = []
for ilab in labs:
xlocs.append(ilab.get_window_extent().x0)
print(xlocs)
x0 = min(xlocs)
trans = transforms.blended_transform_factory(IdentityTransform(), ax.transAxes)
plt.text(x0-2.5,-0.2,'Source: blablablablablablablablablablablablablablablablabla',ha='left',transform=trans)
plt.savefig("flush.png",bbox_inches="tight")
I have a catplot drawing using:
s = sns.catplot(x="level", y="value", hue="cond", kind=graph_type, data=df)
However, the size of the groups is not equal:
"Minimal" has n=12 samples , and "Moderate" has n=18 samples.
How can I add this info to the graph?
Manually calculate the sizes and add them to xticklabels, something like this
import matplotlib.pyplot as plt
import seaborn as sns
exercise = sns.load_dataset("exercise")
cnts = dict(exercise['time'].value_counts())
key = list(cnts.keys())
vals = list(cnts.values())
g = sns.catplot(x="time", y="pulse", hue="kind",order=key,
data=exercise, kind="box")
g.set_axis_labels("", "pulse")
g.set_xticklabels([(key[i]+'\n('+str(vals[i])+')') for i in range(len(key))])
plt.show()
So I want my image look like this
But now my image look like this
How do I reduce the space between bars without making the bar width into 1?
Here is my code:
plot=repeat.loc['mean'].plot(kind='bar',rot=0,alpha=1,cmap='Reds',
yerr=repeat.loc['std'],error_kw=dict(elinewitdh=0.02,ecolor='grey'),
align='center',width=0.2,grid=None)
plt.ylabel('')
plt.grid(False)
plt.title(cell,ha='center')
plt.xticks([])
plt.yticks([])
plt.ylim(0,120)
plt.tight_layout()`
make the plot from scratch if the toplevel functions from pandas or seaborn do not give you the desired result! :)
import seaborn.apionly as sns
import scipy as sp
import matplotlib.pyplot as plt
# some fake data
data = sp.randn(10,10) + 1
data = data[sp.argsort(sp.average(data,axis=1))[::-1],:]
avg = sp.average(data,axis=1)
std = sp.std(data,axis=1)
# a practical helper from seaborn to quickly generate the colors
colors = sns.color_palette('Reds',n_colors = data.shape[0])
fig, ax = plt.subplots()
pos = range(10)
ax.bar(pos,avg,width=1)
for col,patch in zip(colors,ax.patches):
patch.set_facecolor(col)
patch.set_edgecolor('k')
for i,p in enumerate(pos):
ax.plot([p,p],[avg[i],avg[i]+std[i]],color='k',lw=2, zorder=-1)
I have created a histogram with matplotlib using the pyplot.hist() function. I would like to add a Poison error square root of bin height (sqrt(binheight)) to the bars. How can I do this?
The return tuple of .hist() includes return[2] -> a list of 1 Patch objects. I could only find out that it is possible to add errors to bars created via pyplot.bar().
Indeed you need to use bar. You can use to output of hist and plot it as a bar:
import numpy as np
import pylab as plt
data = np.array(np.random.rand(1000))
y,binEdges = np.histogram(data,bins=10)
bincenters = 0.5*(binEdges[1:]+binEdges[:-1])
menStd = np.sqrt(y)
width = 0.05
plt.bar(bincenters, y, width=width, color='r', yerr=menStd)
plt.show()
Alternative Solution
You can also use a combination of pyplot.errorbar() and drawstyle keyword argument. The code below creates a plot of the histogram using a stepped line plot. There is a marker in the center of each bin and each bin has the requisite Poisson errorbar.
import numpy
import pyplot
x = numpy.random.rand(1000)
y, bin_edges = numpy.histogram(x, bins=10)
bin_centers = 0.5*(bin_edges[1:] + bin_edges[:-1])
pyplot.errorbar(
bin_centers,
y,
yerr = y**0.5,
marker = '.',
drawstyle = 'steps-mid-'
)
pyplot.show()
My personal opinion
When plotting the results of multiple histograms on the the same figure, line plots are easier to distinguish. In addition, they look nicer when plotting with a yscale='log'.