4.15. DataFrame Statistics¶
.count().value_counts().nunique().sum().cumsum().prod().cumprod().min().idxmin().cummin().max().idxmax().cummax().mean().median().mode().rolling(window=3).mean().abs().std().mad()- Mean absolute deviation.sem()- Standard Error of the Mean (SEM).skew()- Skewness (3rd moment).kurt()- Kurtosis (4th moment).quantile(.33)- Sample quantile (value at %). Quantile also known as Percentile.quantile([.25, .5, .75]).var().corr().describe().nsmallest().values().rank()
4.15.1. SetUp¶
>>> import pandas as pd
>>> import numpy as np
>>> np.random.seed(0)
>>>
>>>
>>> df = pd.DataFrame(
... columns = ['Morning', 'Noon', 'Evening', 'Midnight'],
... index = pd.date_range('1999-12-30', periods=7),
... data = np.random.randn(7, 4))
>>>
>>> df
Morning Noon Evening Midnight
1999-12-30 1.764052 0.400157 0.978738 2.240893
1999-12-31 1.867558 -0.977278 0.950088 -0.151357
2000-01-01 -0.103219 0.410599 0.144044 1.454274
2000-01-02 0.761038 0.121675 0.443863 0.333674
2000-01-03 1.494079 -0.205158 0.313068 -0.854096
2000-01-04 -2.552990 0.653619 0.864436 -0.742165
2000-01-05 2.269755 -1.454366 0.045759 -0.187184
4.15.2. Count¶
Number of non-null observations:
>>> df.count()
Morning 7
Noon 7
Evening 7
Midnight 7
dtype: int64
>>> df.value_counts()
Morning Noon Evening Midnight
-2.552990 0.653619 0.864436 -0.742165 1
-0.103219 0.410599 0.144044 1.454274 1
0.761038 0.121675 0.443863 0.333674 1
1.494079 -0.205158 0.313068 -0.854096 1
1.764052 0.400157 0.978738 2.240893 1
1.867558 -0.977278 0.950088 -0.151357 1
2.269755 -1.454366 0.045759 -0.187184 1
dtype: int64
>>> df.nunique()
Morning 7
Noon 7
Evening 7
Midnight 7
dtype: int64
4.15.3. Sum¶
Sum of values:
df.sum() Morning 5.500273 Noon -1.050752 Evening 3.739996 Midnight 2.094039 dtype: float64
Cumulative sum:
>>> df.cumsum()
Morning Noon Evening Midnight
1999-12-30 1.764052 0.400157 0.978738 2.240893
1999-12-31 3.631610 -0.577121 1.928826 2.089536
2000-01-01 3.528391 -0.166522 2.072870 3.543809
2000-01-02 4.289429 -0.044847 2.516733 3.877484
2000-01-03 5.783508 -0.250005 2.829801 3.023388
2000-01-04 3.230518 0.403613 3.694237 2.281223
2000-01-05 5.500273 -1.050752 3.739996 2.094039
4.15.4. Product¶
Product of values:
>>> df.prod()
Morning 2.240538
Noon -0.003810
Evening 0.000736
Midnight 0.019528
dtype: float64
Cumulative product:
>>> df.cumprod()
Morning Noon Evening Midnight
1999-12-30 1.764052 0.400157 0.978738 2.240893
1999-12-31 3.294470 -0.391065 0.929888 -0.339175
2000-01-01 -0.340051 -0.160571 0.133944 -0.493254
2000-01-02 -0.258792 -0.019537 0.059453 -0.164586
2000-01-03 -0.386656 0.004008 0.018613 0.140572
2000-01-04 0.987128 0.002620 0.016090 -0.104328
2000-01-05 2.240538 -0.003810 0.000736 0.019528
4.15.5. Extremes¶
Minimum, index of minimum and cumulative minimum:
>>> df.min()
Morning -2.552990
Noon -1.454366
Evening 0.045759
Midnight -0.854096
dtype: float64
>>> df.idxmin()
Morning 2000-01-04
Noon 2000-01-05
Evening 2000-01-05
Midnight 2000-01-03
dtype: datetime64[ns]
>>> df.cummin()
Morning Noon Evening Midnight
1999-12-30 1.764052 0.400157 0.978738 2.240893
1999-12-31 1.764052 -0.977278 0.950088 -0.151357
2000-01-01 -0.103219 -0.977278 0.144044 -0.151357
2000-01-02 -0.103219 -0.977278 0.144044 -0.151357
2000-01-03 -0.103219 -0.977278 0.144044 -0.854096
2000-01-04 -2.552990 -0.977278 0.144044 -0.854096
2000-01-05 -2.552990 -1.454366 0.045759 -0.854096
Maximum, index of maximum and cumulative maximum:
>>> df.max()
Morning 2.269755
Noon 0.653619
Evening 0.978738
Midnight 2.240893
dtype: float64
>>> df.idxmax()
Morning 2000-01-05
Noon 2000-01-04
Evening 1999-12-30
Midnight 1999-12-30
dtype: datetime64[ns]
>>> df.cummax()
Morning Noon Evening Midnight
1999-12-30 1.764052 0.400157 0.978738 2.240893
1999-12-31 1.867558 0.400157 0.978738 2.240893
2000-01-01 1.867558 0.410599 0.978738 2.240893
2000-01-02 1.867558 0.410599 0.978738 2.240893
2000-01-03 1.867558 0.410599 0.978738 2.240893
2000-01-04 1.867558 0.653619 0.978738 2.240893
2000-01-05 2.269755 0.653619 0.978738 2.240893
4.15.6. Average¶
Arithmetic mean of values:
>>> df.mean()
Morning 0.785753
Noon -0.150107
Evening 0.534285
Midnight 0.299148
dtype: float64
Arithmetic median of values:
>>> df.median()
Morning 1.494079
Noon 0.121675
Evening 0.443863
Midnight -0.151357
dtype: float64
Mode:
>>> df.mode()
Morning Noon Evening Midnight
0 -2.552990 -1.454366 0.045759 -0.854096
1 -0.103219 -0.977278 0.144044 -0.742165
2 0.761038 -0.205158 0.313068 -0.187184
3 1.494079 0.121675 0.443863 -0.151357
4 1.764052 0.400157 0.864436 0.333674
5 1.867558 0.410599 0.950088 1.454274
6 2.269755 0.653619 0.978738 2.240893
Rolling Average:
>>> df.rolling(window=30)
Rolling [window=30,center=False,axis=0,method=single]
>>>
>>> df.rolling(window=3).mean()
Morning Noon Evening Midnight
1999-12-30 NaN NaN NaN NaN
1999-12-31 NaN NaN NaN NaN
2000-01-01 1.176130 -0.055507 0.690957 1.181270
2000-01-02 0.841792 -0.148335 0.512665 0.545530
2000-01-03 0.717299 0.109038 0.300325 0.311284
2000-01-04 -0.099291 0.190045 0.540456 -0.420862
2000-01-05 0.403615 -0.335302 0.407754 -0.594482
Figure 4.9. Rolling Average¶
4.15.7. Distribution¶
Absolute value:
>>> df.abs()
Morning Noon Evening Midnight
1999-12-30 1.764052 0.400157 0.978738 2.240893
1999-12-31 1.867558 0.977278 0.950088 0.151357
2000-01-01 0.103219 0.410599 0.144044 1.454274
2000-01-02 0.761038 0.121675 0.443863 0.333674
2000-01-03 1.494079 0.205158 0.313068 0.854096
2000-01-04 2.552990 0.653619 0.864436 0.742165
2000-01-05 2.269755 1.454366 0.045759 0.187184
Standard deviation:
>>> df.std()
Morning 1.671798
Noon 0.787967
Evening 0.393169
Midnight 1.151785
dtype: float64
Figure 4.10. Standard Deviation¶
Mean absolute deviation:
>>> df.mad()
Morning 1.214980
Noon 0.624708
Evening 0.340116
Midnight 0.894684
dtype: float64
Standard Error of the Mean (SEM):
>>> df.sem()
Morning 0.631880
Noon 0.297824
Evening 0.148604
Midnight 0.435334
dtype: float64
Figure 4.11. Standard Error of the Mean (SEM)¶
Skewness (3rd moment):
>>> df.skew()
Morning -1.602706
Noon -0.907414
Evening 0.031047
Midnight 0.915190
dtype: float64
Figure 4.12. Skewness¶
Kurtosis (4th moment):
>>> df.kurt()
Morning 2.502051
Noon -0.588010
Evening -2.208781
Midnight -0.351782
dtype: float64
Figure 4.13. Kurtosis¶
Sample quantile (value at %). Quantile also known as Percentile:
>>> df.quantile(.33)
Morning 0.743753
Noon -0.220601
Evening 0.309687
Midnight -0.198283
Name: 0.33, dtype: float64
>>> df.quantile([.25, .5, .75])
Morning Noon Evening Midnight
0.25 0.328909 -0.591218 0.228556 -0.464674
0.50 1.494079 0.121675 0.443863 -0.151357
0.75 1.815805 0.405378 0.907262 0.893974
Variance:
>>> df.var()
Morning 2.794907
Noon 0.620892
Evening 0.154582
Midnight 1.326610
dtype: float64
Correlation Coefficient:
>>> df.corr()
Morning Noon Evening Midnight
Morning 1.000000 -0.698340 -0.190219 0.201034
Noon -0.698340 1.000000 0.307686 0.359761
Evening -0.190219 0.307686 1.000000 0.136436
Midnight 0.201034 0.359761 0.136436 1.000000
Figure 4.14. Correlation Coefficient¶
4.15.8. Describe¶
>>> df.describe()
Morning Noon Evening Midnight
count 7.000000 7.000000 7.000000 7.000000
mean 0.785753 -0.150107 0.534285 0.299148
std 1.671798 0.787967 0.393169 1.151785
min -2.552990 -1.454366 0.045759 -0.854096
25% 0.328909 -0.591218 0.228556 -0.464674
50% 1.494079 0.121675 0.443863 -0.151357
75% 1.815805 0.405378 0.907262 0.893974
max 2.269755 0.653619 0.978738 2.240893
4.15.9. Examples¶
>>> import pandas as pd
>>>
>>>
>>> DATA = 'https://python.astrotech.io/_static/phones-en.csv'
>>>
>>> df = pd.read_csv(DATA, parse_dates=['date'])
>>> df.drop(columns='index', inplace=True)
- date
The date and time of the entry
- duration
The duration (in seconds) for each call, the amount of data (in MB) for each data entry, and the number of texts sent (usually 1) for each sms entry
- item
A description of the event occurring – can be one of call, sms, or data
- month
The billing month that each entry belongs to – of form
YYYY-MM- network
The mobile network that was called/texted for each entry
- network_type
Whether the number being called was a mobile, international ('world'), voicemail, landline, or other ('special') number.
Source 1
How many rows the dataset:
>>> df['item'].count()
830
What was the longest phone call / data entry?:
>>> df['duration'].max()
10528.0
How many seconds of phone calls are recorded in total?:
>>> df.loc[ df['item'] == 'call' ]['duration'].sum()
92321.0
How many entries are there for each month?:
>>> df['month'].value_counts()
2014-11 230
2015-01 205
2014-12 157
2015-02 137
2015-03 101
Name: month, dtype: int64
Number of non-null unique network entries:
>>> df['network'].nunique()
9
4.15.10. Other¶
.nsmallest()
.values()
.rank()
4.15.11. References¶
- 1
Lynn, Shane. Summarising, Aggregating, and Grouping data in Python Pandas. https://www.shanelynn.ie/summarising-aggregation-and-grouping-data-in-python-pandas/ Access date: 2019-12-03. 2019.
4.15.12. Assignments¶
"""
* Assignment: DataFrame Statistics
* Complexity: medium
* Lines of code: 15 lines
* Time: 21 min
English:
TODO: English Translation
X. Run doctests - all must succeed
Polish:
1. Ustaw ziarno losowości na zero
2. Stwórz `df: pd.DataFrame` z 50 wierszami:
a. kolumna `mileage` - losowe `int` [0, 200_000)
b. kolumna `consumption` - losowe `int` [0, 20)
3. Dodaj kolumnę `status` o wartościach:
a. `old` jeżeli `mileage` powyżej 100_000 km
b. `young` jeżeli `mileage` od 10_000 km do 50_000 km
c. `new` jeżeli `mileage` od 0 do 10_000 km
4. Używając `pd.cut` dodaj kolumnę `type`:
a. jeżeli `consumption` [0, 1] `type` to `electric`
b. jeżeli `consumption` [2, 10] `type` to `car`
c. jeżeli `consumption` 11 i więcej, `type` to `truck`
5. Przeanalizuj dane statystycznie:
a. Zapisz podstawowe statystyki opisowe (`DataFrame.describe()`) do `result: pd.DataFrame`
b. Sprawdź liczność grup (`DataFrame.count()`, `Series.value_counts()`)
6. Uruchom doctesty - wszystkie muszą się powieść
Extra Task:
1. (wymaga wiedzy z przyszłych rozdziałów)
2. Narysuj histogram dla `consumption`
3. Pogrupuj dane po `type` i `status` a następnie wypisz statystyki opisowe
4. Pogrupuj dane po `type` i `status`, wypisz statystyki opisowe a następnie je transponuj
Tests:
>>> import sys; sys.tracebacklimit = 0
>>> pd.set_option('display.width', 500)
>>> pd.set_option('display.max_columns', 10)
>>> pd.set_option('display.max_rows', 10)
>>> assert result is not Ellipsis, \
'Assign result to variable: `result`'
>>> assert type(result) is pd.DataFrame, \
'Variable `result` must be a `pd.DataFrame` type'
>>> result # doctest: +NORMALIZE_WHITESPACE
mileage consumption
count 50.00000 50.000000
mean 110421.02000 9.320000
std 53170.24328 6.244802
min 7877.00000 0.000000
25% 71239.75000 4.000000
50% 115186.00000 9.000000
75% 154889.00000 14.750000
max 199827.00000 20.000000
"""
import pandas as pd
import numpy as np
np.random.seed(0)
df = pd.DataFrame({
'mileage': np.random.randint(0, 200_000, size=50),
'consumption': np.random.randint(0, 21, size=50),
})
# type: pd.DataFrame
result = ...