I have a dataset that I want to plot with FacetGrids using the seaborn library. The problem is my data is "sparse"; some of the individual subplots don't exist (ie. there are zero data points). I would like those cells to either not show up, or just show up and be blank, but still see the subplots that have data. Here's a simple example:
import pandas as pd
import seaborn as sns
import matplotlib.pyplot as plt
df = pd.DataFrame(columns=['a','b','c','d'],
data=[[1,1,1,4],[1,2,2,8],[2,1,2,12],[2,1,3,14]])
print df
g = sns.FacetGrid(df, col='a', row='b', hue='c')
g.map(plt.scatter, 'c', 'd', marker='o')
Unfortunately, when I plot this, I just get four empty plots instead of 3 filled plots and one empty one. If I change the last row of data to [2,2,3,14] instead, then all four plots appear as expected. Is this a bug in seaborn? Can I work around it somehow?
Related
The plot below shows the correlation for one column. The problem is that the numbers are not readable, because there are many columns in it.
How is it possible to show only 5 or 6 most important columns and not all of them with very low importance?
plt.figure(figsize=(20,3))
sns.heatmap(df.corr()[['price']].sort_values('price', ascending=False).iloc[1:].T, annot=True,
cmap='Spectral_r', vmax=0.9, vmin=-0.31)
You can limit the cells shown via .iloc[1:7]. If you also want to show the highest negative values, you could create a second plot with .iloc[-6:]. To have both together, you could use numpy's slicing function and write .iloc[np.r_[1:4, -3:0]].
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns
df = pd.DataFrame(np.random.rand(7, 27), columns=['price'] + [*'abcdefghijklmnopqrstuvwxyz'])
plt.figure(figsize=(20, 3))
sns.heatmap(df.corr()[['price']].sort_values('price', ascending=False).iloc[1:7].T,
annot=True, annot_kws={'rotation':90, 'size': 20},
cmap='Spectral_r', vmax=0.9, vmin=-0.31)
plt.show()
annot can also be a list of labels. Using this, you can define a string matrix that you use to display the desired numbers and set the others to an empty string.
import matplotlib.pyplot as plt
import numpy as np; np.random.seed(0)
import seaborn as sns; sns.set_theme()
import pandas as pd
from string import ascii_letters
# generate random data
rs = np.random.RandomState(33)
df = pd.DataFrame(data=rs.normal(size=(100, 26)),
columns=list(ascii_letters[26:]))
importance_index = 5 # until which idx to hide values
data = df.corr()[['A']].sort_values('A', ascending=False).iloc[1:].T
labels = data.astype(str) # make a str-copy
labels.iloc[0,:importance_index] = ' ' # mask columns that you want to hide
sns.heatmap(data, annot=labels, cmap='Spectral_r', vmax=0.9, vmin=-0.31, fmt='', annot_kws={'rotation':90})
plt.show()
The output on some random data:
This works but it has its limits, particulary with setting fmt='' (can't use it to conveniently format decimals anymore, need to do it manually now). I would also question whether your approach is even the best one to take here. I think consistency in plots is quite important. I would rather evaluate if we can't rotate the heatmap labels (I've included it above) or leave them out completely since it is technically redundant due to the color-coding. Alternatively, you could only plot the cells with the "important" values.
I have the following Dataset and I wanna create a plot, which to columns compares with each other.
import pandas as pd
import matplotlib.pyplot as plt
import numpy as np
ds=pd.read_csv('h-t-t-p-:bit.ly/uforeports') #My DataSet
ds.head(5) # Only the fist 5 rows to show
ds1= ds.head(4).drop(['Colors Reported','State'],axis=1) # Droping of unnecesssary rows
print(ds1)
Now I wanna compare "City" and "Shape Reported" with help of plotting. I found something with Pandas but this is not so elegant!
x=ds.loc[0:100,['State']]
y=ds.loc[0:100,['Shape Reported']]
x.apply(pd.value_counts).plot(kind='bar', subplots=True)
y.apply(pd.value_counts).plot(kind='bar', subplots=True)
Do you know a better solution with Matplotlib to this problem?
This is what I want
It's not exactly clear how you want to compare them.
The simplest way of drawing a bar chart is:
df['State'].value_counts().plot.bar()
df['Shape Reported'].value_counts().plot.bar()
If you just want to do it for the first 100 rows as in your example, just add head(100):
df['State'].head(100).value_counts().plot.bar()
df['Shape Reported'].head(100).value_counts().plot.bar()
EDIT:
To compare the two values you can plot a bivariate distribution plot. This is easily done with seaborn:
import seaborn
sns.displot(df,x='State', y='Shape Reported', height=6, aspect=1.33)
Result:
From my excel imported file, I want to plot specific entries i.e.rows and columns but plt.plot command does not display the data, only a blank frame is shown. please see the attached picture.
May be it has something to do with my code.
%matplotlib inline
import pandas as pd
import matplotlib.pyplot as plt
hpge = pd.read_excel('mypath\\filename.xlsx','Sheet3', skiprows=1,usecols='C:G,I,J')
x=[]
y=[]
x.append(hpge.E_KeV[2700:2900])# E_KeV is a column
y.append(hpge.Fcounts[2700:2900])# Fcounts is a column
x1=[]
y1=[]
x1.append(hpge.E[2700:2900])
y1.append(hpge.C[2700:2900])
#print(y1)
#print(x)
#plt.xlim(590,710)
#plt.yscale('log')
plt.plot(x, y, label='Cs')
plt.plot(x1,y1)
plt.show()
The following code when graphed looks really messy at the moment. The reason is I have too many values for 'fare'. 'Fare' ranges from [0-500] with most of the values within the first 100.
import pandas as pd
import numpy as np
import seaborn as sns
import matplotlib.pyplot as plt
titanic = sns.load_dataset("titanic")
y =titanic.groupby([titanic.fare//1,'sex']).survived.mean().reset_index()
sns.set(style="whitegrid")
g = sns.factorplot(x='fare', y= 'survived', col = 'sex', kind ='bar' ,data= y,
size=4, aspect =2.5 , palette="muted")
g.despine(left=True)
g.set_ylabels("Survival Probability")
g.set_xlabels('Fare')
plt.show()
I would like to try slicing up the 'fare' of the plots into subsets but would like to see all the graphs at the same time on one screen. I was wondering it this is possible without having to resort to groupby.
I will have to play around with the values of 'fare' to see what I would want each graph to represent, but for a sample let's use break up the graph into these 'fare' values.
[0-18]
[18-35]
[35-70]
[70-300]
[300-500]
So the total would be 10 graphs on one page, because of the juxtaposition with the opposite sex.
Is it possible with Seaborn? Do I need to do a lot of configuring with matplotlib? Thanks.
Actually I wrote a little blog post about this a while ago. If you are plotting histograms you can use the by keyword:
import matplotlib.pyplot as plt
import seaborn.apionly as sns
sns.set() #rescue matplotlib's styles from the early '90s
data = sns.load_dataset('titanic')
data.hist(by='class', column = 'fare')
plt.show()
Otherwise if you're just plotting value-counts, you have to roll your own grid:
def categorical_hist(self,column,by,layout=None,legend=None,**params):
from math import sqrt, ceil
if layout==None:
s = ceil(sqrt(self[column].unique().size))
layout = (s,s)
return self.groupby(by)[column]\
.value_counts()\
.sort_index()\
.unstack()\
.plot.bar(subplots=True,layout=layout,legend=None,**params)
categorical_hist(data, by='class', column='embark_town')
Edit If you want survival rate by fare range, you could do something like this
data.groupby(pd.cut(data.fare,10)).apply(lambda x.survived.sum(): x./len(x))
I am trying to plot bar chart using seaborn. Sample data:
x=[1,1000,1001]
y=[200,300,400]
cat=['first','second','third']
df = pd.DataFrame(dict(x=x, y=y,cat=cat))
When I use:
sns.factorplot("x","y", data=df,kind="bar",palette="Blues",size=6,aspect=2,legend_out=False);
The figure produced is
When I add the legend
sns.factorplot("x","y", data=df,hue="cat",kind="bar",palette="Blues",size=6,aspect=2,legend_out=False);
The resulting figure looks like this
As you can see, the bar is shifted from the value. I don't know how to get the same layout as I had in the first figure and add the legend.
I am not necessarily tied to seaborn, I like the color palette, but any other approach is fine with me. The only requirement is that the figure looks like the first one and has the legend.
It looks like this issue arises here - from the docs searborn.factorplot
hue : string, optional
Variable name in data for splitting the plot by color. In the case of ``kind=”bar”, this also influences the placement on the x axis.
So, since seaborn uses matplotlib, you can do it like this:
import matplotlib.pyplot as plt
import numpy as np
import seaborn as sns
x=[1,1000,1001]
y=[200,300,400]
sns.set_context(rc={"figure.figsize": (8, 4)})
nd = np.arange(3)
width=0.8
plt.xticks(nd+width/2., ('1','1000','1001'))
plt.xlim(-0.15,3)
fig = plt.bar(nd, y, color=sns.color_palette("Blues",3))
plt.legend(fig, ['First','Second','Third'], loc = "upper left", title = "cat")
plt.show()
Added #mwaskom's method to get the three sns colors.