How to adjust x axis labels in a seaborn plot? - python

I am trying to plot histogram similar to this:Actual plot
However, I am unable to customize the x axis labels similar to the above figure.
My seaborn plot looks something like this,
my plot
I want the same x-axis labels ranging from 0 to 25000 with equal interval of 5000. It would be great if anyone can guide me in the right direction?
Code for my figure:
sns.set_style('darkgrid')
kws = dict(linewidth=.3, edgecolor='k')
g = sns.FacetGrid(college, hue='Private',size=6, aspect=2, palette = 'coolwarm')
g = g.map(plt.hist, 'Outstate', bins=24,alpha = 0.7,**kws).add_legend()

You should be able to do that by simply add:
plt.xticks(np.linspace(start=0, stop=25000, num=6))

Related

How to affect a list of colors to histogram index bar in matplotlib?

I have the the folowing dataframe "freqs2" with index (SD to SD17) and associated values (frequencies) :
freqs
SD 101
SD2 128
...
SD17 65
I would like to affect a list of precise colors (in order) for each index. I've tried the following code :
colors=['#e5243b','#DDA63A', '#4C9F38','#C5192D','#FF3A21','#26BDE2','#FCC30B','#A21942','#FD6925','#DD1367','#FD9D24','#BF8B2E','#3F7E44','#0A97D9','#56C02B','#00689D','#19486A']
freqs2.plot.bar(freqs2.index, legend=False,rot=45,width=0.85, figsize=(12, 6),fontsize=(14),color=colors )
plt.ylabel('Frequency',fontsize=(17))
As result I obtain all my chart bars in red color (first color of the list).
Based on similar questions, I've tried to integrate "freqs2.index" to stipulate that the list of colors concern index but the problem stay the same.
It looks like a bug in pandas, plotting directly in matplotlib or using seaborn (which I recommend) works:
import seaborn as sns
colors=['#e5243b','#dda63a', '#4C9F38','#C5192D','#FF3A21','#26BDE2','#FCC30B','#A21942','#FD6925','#DD1367','#FD9D24','#BF8B2E','#3F7E44','#0A97D9','#56C02B','#00689D','#19486A']
# # plotting directly with matplotlib works too:
# fig = plt.figure()
# ax = fig.add_axes([0,0,1,1])
# ax.bar(x=df.index, height=df['freqs'], color=colors)
ax = sns.barplot(data=df, x= df.index, y='freqs', palette=colors)
ax.tick_params(axis='x', labelrotation=45)
plt.ylabel('Frequency',fontsize=17)
plt.show()
Edit: an issue already exists on Github

How to use a 3rd dataframe column as x axis ticks/labels in matplotlib scatter

I'm struggling to wrap my head around matplotlib with dataframes today. I see lots of solutions but I'm struggling to relate them to my needs. I think I may need to start over. Let's see what you think.
I have a dataframe (ephem) with 4 columns - Time, Date, Altitude & Azimuth.
I produce a scatter for alt & az using:
chart = plt.scatter(ephem.Azimuth, ephem.Altitude, marker='x', color='black', s=8)
What's the most efficient way to set the values in the Time column as the labels/ticks on the x axis?
So:
the scale/gridlines etc all remain the same
the chart still plots alt and az
the y axis ticks/labels remain as is
only the x axis ticks/labels are changed to the Time column.
Thanks
This isn't by any means the cleanest piece of code but the following works for me:
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.scatter(ephem.Azimuth, ephem.Altitude, marker='x', color='black', s=8)
labels = list(ephem.Time)
ax.set_xticklabels(labels)
plt.show()
Here you will explicitly force the set_xticklabels to the dataframe Time column which you have.
In other words, you want to change the x-axis tick labels using a list of values.
labels = ephem.Time.tolist()
# make your plot and before calling plt.show()
# insert the following two lines
ax = plt.gca()
ax.set_xticklabels(labels = labels)
plt.show()

seaborn distplot different bar width on each figure

Sorry for giving an image however I think it is the best way to show my problem.
As you can see all of the bin width are different, from my understanding it shows range of rent_hours. I am not sure why different figure have different bin width even though I didn't set any.
My code looks is as follows:
figure, axes = plt.subplots(nrows=4, ncols=3)
figure.set_size_inches(18,14)
plt.subplots_adjust(hspace=0.5)
for ax, age_g in zip(axes.ravel(), age_cat):
group = total_usage_df.loc[(total_usage_df.age_group == age_g) & (total_usage_df.day_of_week <= 4)]
sns.distplot(group.rent_hour, ax=ax, kde=False)
ax.set(title=age_g)
ax.set_xlim([0, 24])
figure.suptitle("Weekday usage pattern", size=25);
additional question:
Seaborn : How to get the count in y axis for distplot using PairGrid for here it says that kde=False makes y-axis count however http://seaborn.pydata.org/generated/seaborn.distplot.html in the doc, it uses kde=False and still seems to show something else. How can I set y-axis to show count?
I've tried
sns.distplot(group.rent_hour, ax=ax, norm_hist=True) and it still seems to give something else rather than count.
sns.distplot(group.rent_hour, ax=ax, kde=False) gives me count however I don't know why it is giving me count.
Answer 1:
From the documentation:
norm_hist : bool, optional
If True, the histogram height shows a density rather than a count.
This is implied if a KDE or fitted density is plotted.
So you need to take into account your bin width as well, i.e. compute the area under the curve and not just the sum of the bin heights.
Answer 2:
# Plotting hist without kde
ax = sns.distplot(your_data, kde=False)
# Creating another Y axis
second_ax = ax.twinx()
#Plotting kde without hist on the second Y axis
sns.distplot(your_data, ax=second_ax, kde=True, hist=False)
#Removing Y ticks from the second axis
second_ax.set_yticks([])

How to prevent overlapping x-axis labels in sns.countplot

For the plot
sns.countplot(x="HostRamSize",data=df)
I got the following graph with x-axis label mixing together, how do I avoid this? Should I change the size of the graph to solve this problem?
Having a Series ds like this
import pandas as pd
import seaborn as sns
import matplotlib.pyplot as plt
import numpy as np; np.random.seed(136)
l = "1234567890123"
categories = [ l[i:i+5]+" - "+l[i+1:i+6] for i in range(6)]
x = np.random.choice(categories, size=1000,
p=np.diff(np.array([0,0.7,2.8,6.5,8.5,9.3,10])/10.))
ds = pd.Series({"Column" : x})
there are several options to make the axis labels more readable.
Change figure size
plt.figure(figsize=(8,4)) # this creates a figure 8 inch wide, 4 inch high
sns.countplot(x="Column", data=ds)
plt.show()
Rotate the ticklabels
ax = sns.countplot(x="Column", data=ds)
ax.set_xticklabels(ax.get_xticklabels(), rotation=40, ha="right")
plt.tight_layout()
plt.show()
Decrease Fontsize
ax = sns.countplot(x="Column", data=ds)
ax.set_xticklabels(ax.get_xticklabels(), fontsize=7)
plt.tight_layout()
plt.show()
Of course any combination of those would work equally well.
Setting rcParams
The figure size and the xlabel fontsize can be set globally using rcParams
plt.rcParams["figure.figsize"] = (8, 4)
plt.rcParams["xtick.labelsize"] = 7
This might be useful to put on top of a juypter notebook such that those settings apply for any figure generated within. Unfortunately rotating the xticklabels is not possible using rcParams.
I guess it's worth noting that the same strategies would naturally also apply for seaborn barplot, matplotlib bar plot or pandas.bar.
You can rotate the x_labels and increase their font size using the xticks methods of pandas.pyplot.
For Example:
import matplotlib.pyplot as plt
plt.figure(figsize=(10,5))
chart = sns.countplot(x="HostRamSize",data=df)
plt.xticks(
rotation=45,
horizontalalignment='right',
fontweight='light',
fontsize='x-large'
)
For more such modifications you can refer this link:
Drawing from Data
If you just want to make sure xticks labels are not squeezed together, you can set a proper fig size and try fig.autofmt_xdate().
This function will automatically align and rotate the labels.
plt.figure(figsize=(15,10)) #adjust the size of plot
ax=sns.countplot(x=df['Location'],data=df,hue='label',palette='mako')
ax.set_xticklabels(ax.get_xticklabels(), rotation=40, ha="right") #it will rotate text on x axis
plt.tight_layout()
plt.show()
you can try this code & change size & rotation according to your need.
I don't know whether it is an option for you but maybe turning the graphic could be a solution (instead of plotting on x=, do it on y=), such that:
sns.countplot(y="HostRamSize",data=df)

matplotlib pyplot 2 plots with different axes in same figure

I have a small issue with matplotlib.pyplot and I hope someone might have come across it before.
I have data that contain X,Y,e values that are the X, Y measurements of a variable and e are the errors of the measurements in Y. I need to plot them in a log log scale.
I use the plt.errorbars function to plot them and then set yscale and xscale to log and this works fine. But I need to also plot a line on the same graph that needs to be in linear scale.
I am able to have the plots done separately just fine but I would like to have them in the same image if possible. Do you have any ideas? I am posting what I have done for now.
Cheers,
Kimon
tdlist = np.array([0.01,0.02,0.05,0.1,0.2,0.3,0.4,0.5,0.8,1,2,5,10,15,20,25,30,40,60,80,100,150,200,250,300,400])
freqlist=np.array([30,40,50,60,70,80,90,100,110,120,140,160,180,200,220,250,300,350,400,450])
filename=opts.filename
data = reader(filename)
data2 = logconv(data)
#x,y,e the data. Calculating usefull sums
x = data2[0]
y = data2[1]
e = data2[2]
xoe2 = np.sum(x/e**2)
yoe2 = np.sum(y/e**2)
xyoe2 = np.sum(x*y/e**2)
oe2 = np.sum(1/e**2)
x2oe2 = np.sum(x**2/e**2)
aslope = (xoe2*yoe2-xyoe2*oe2)/(xoe2**2-x2oe2*oe2)
binter = (xyoe2-aslope*x2oe2)/xoe2
aerr = np.sqrt(oe2/(x2oe2*oe2-xoe2**2))
berr = np.sqrt(x2oe2/(x2oe2*oe2-xoe2**2))
print('slope is ',aslope,' +- ', aerr)
print('inter is ',binter,' +- ', berr)
fig = plt.figure()
ax1 = fig.add_subplot(1,1,1)
ax2 = fig.add_axes(ax1.get_position(), frameon=False)
ax1.errorbar(data[0],data[1],yerr=data[2],fmt='o')
ax1.set_xscale('log',basex=10)
ax1.set_yscale('log',basey=10)
ax1.set_yticks([])
ax1.set_xticks([])
ax2.plot(x,aslope*x+binter,'r')
ax2.plot(x,(aslope-aerr)*x+(binter+berr),'--')
ax2.plot(x,(aslope+aerr)*x+(binter-berr),'--')
ax2.set_xscale('linear')
ax2.set_yscale('linear')
plt.xticks(np.log10(freqlist),freqlist.astype('int'))
plt.yticks(np.log10(tdlist),tdlist.astype('float'))
plt.xlabel('Frequency (MHz)')
plt.ylabel('t_s (msec)')
fitndx1 = 'Fit slope '+"{0:.2f}".format(aslope)+u"\u00B1"+"{0:.2f}".format(aerr)
plt.legend(('Data',fitndx1))
plt.show()
Following Molly's suggestion I managed to get closer to my goal but still not there. I am adding a bit more info for what I am trying to do and it might clarify things a bit.
I am setting ax1 to the errobar plot that uses loglog scale. I need to use errorbar and not loglog plot so that I can display the errors with my points.
I am using ax2 to plot the linear fit in linealinear scale.
Moreover I do not want the x and y axes to display values that are 10,100,1000 powers of ten but my own axes labels that have the spacing I want therefore I am using the plt.xticks. I tried ax1.set_yticks and ax1.set_yticklabes but with no success. Below is the image I am getting.
I do not have enough reputation to post an image but here is the link of it uploaded
http://postimg.org/image/uojanigab/
The values of my points should be x range = 40 - 80 and y range = 5 -200 as the fit lines are now.
You can create two overlapping axes using the add_suplot method of figure. Here's an example:
from matplotlib import pyplot as plt
fig = plt.figure()
ax1 = fig.add_subplot(1,1,1)
ax2 = fig.add_axes(ax1.get_position(), frameon=False)
ax1.loglog([1,10,100,1000],[1000,1,100,10])
ax2.plot([5,10,11,13],'r')
plt.show()
You can then turn off the x and y ticks for the linear scale plot like this:
ax2.set_xticks([])
ax2.set_yticks([])
I was not able to get two sets of axis working with the errorbar function so I had to convert everything to log scale including my linear plot. Below is the code I use to get it might be useful to someone.
plt.errorbar(data[0],data[1],yerr=data[2],fmt='o')
plt.xscale('log',basex=10)
plt.yscale('log',basey=10)
plt.plot(data[0],data[0]**aslope*10**binter,'r')
plt.plot(data[0],data[0]**(aslope-aerr)*10**(binter+berr),'--')
plt.plot(data[0],data[0]**(aslope+aerr)*10**(binter-berr),'--')
plt.xticks(freqlist,freqlist.astype('int'))
plt.yticks(tdlist,tdlist.astype('float'))
plt.xlabel('Frequency (MHz)')
plt.ylabel('t_s (msec)')
fitndx1 = 'Fit slope '+"{0:.2f}".format(aslope)+u"\u00B1"+"{0:.2f}".format(aerr)
plt.legend(('Data',fitndx1))
plt.show()
And here is the link to the final image
http://postimg.org/image/bevj2k6nf/

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