Pandas Fundamentals

import pandas as pd
import numpy as np
from matplotlib import pyplot as plt
%matplotlib inline

Pandas Data Structures: Series

A Series represents a one-dimensional array of data. The main difference between a Series and numpy array is that a Series has an index. The index contains the labels that we use to access the data.

There are many ways to create a Series. We will just show a few.

(Data are from the NASA Planetary Fact Sheet.)

names = ['Mercury', 'Venus', 'Earth']
values = [0.3e24, 4.87e24, 5.97e24]
masses = pd.Series(values, index=names)
masses
Mercury    3.000000e+23
Venus      4.870000e+24
Earth      5.970000e+24
dtype: float64

Series have built in plotting methods.

masses.plot(kind='bar')
<AxesSubplot:>
../../_images/basic_pandas_5_1.png

Arithmetic operations and most numpy function can be applied to Series. An important point is that the Series keep their index during such operations.

np.log(masses) / masses**2
Mercury    6.006452e-46
Venus      2.396820e-48
Earth      1.600655e-48
dtype: float64

We can access the underlying index object if we need to:

masses.index
Index(['Mercury', 'Venus', 'Earth'], dtype='object')

Indexing

We can get values back out using the index via the .loc attribute

masses.loc['Earth']
5.97e+24

Or by raw position using .iloc

masses.iloc[2]
5.97e+24

We can pass a list or array to loc to get multiple rows back:

masses.loc[['Venus', 'Earth']]
Venus    4.870000e+24
Earth    5.970000e+24
dtype: float64

And we can even use slice notation

masses.loc['Mercury':'Earth']
Mercury    3.000000e+23
Venus      4.870000e+24
Earth      5.970000e+24
dtype: float64
masses.iloc[:2]
Mercury    3.000000e+23
Venus      4.870000e+24
dtype: float64

If we need to, we can always get the raw data back out as well

masses.values # a numpy array
array([3.00e+23, 4.87e+24, 5.97e+24])
masses.index # a pandas Index object
Index(['Mercury', 'Venus', 'Earth'], dtype='object')

Pandas Data Structures: DataFrame

There is a lot more to Series, but they are limit to a single “column”. A more useful Pandas data structure is the DataFrame. A DataFrame is basically a bunch of series that share the same index. It’s a lot like a table in a spreadsheet.

Below we create a DataFrame.

# first we create a dictionary
data = {'mass': [0.3e24, 4.87e24, 5.97e24],       # kg
        'diameter': [4879e3, 12_104e3, 12_756e3], # m
        'rotation_period': [1407.6, np.nan, 23.9] # h
       }
df = pd.DataFrame(data, index=['Mercury', 'Venus', 'Earth'])
df
mass diameter rotation_period
Mercury 3.000000e+23 4879000.0 1407.6
Venus 4.870000e+24 12104000.0 NaN
Earth 5.970000e+24 12756000.0 23.9

Pandas handles missing data very elegantly, keeping track of it through all calculations.

df.info()
<class 'pandas.core.frame.DataFrame'>
Index: 3 entries, Mercury to Earth
Data columns (total 3 columns):
 #   Column           Non-Null Count  Dtype  
---  ------           --------------  -----  
 0   mass             3 non-null      float64
 1   diameter         3 non-null      float64
 2   rotation_period  2 non-null      float64
dtypes: float64(3)
memory usage: 96.0+ bytes

A wide range of statistical functions are available on both Series and DataFrames.

df.min()
mass               3.000000e+23
diameter           4.879000e+06
rotation_period    2.390000e+01
dtype: float64
df.mean()
mass               3.713333e+24
diameter           9.913000e+06
rotation_period    7.157500e+02
dtype: float64
df.std()
mass               3.006765e+24
diameter           4.371744e+06
rotation_period    9.784237e+02
dtype: float64
df.describe()
mass diameter rotation_period
count 3.000000e+00 3.000000e+00 2.000000
mean 3.713333e+24 9.913000e+06 715.750000
std 3.006765e+24 4.371744e+06 978.423653
min 3.000000e+23 4.879000e+06 23.900000
25% 2.585000e+24 8.491500e+06 369.825000
50% 4.870000e+24 1.210400e+07 715.750000
75% 5.420000e+24 1.243000e+07 1061.675000
max 5.970000e+24 1.275600e+07 1407.600000

We can get a single column as a Series using python’s getitem syntax on the DataFrame object.

df['mass']
Mercury    3.000000e+23
Venus      4.870000e+24
Earth      5.970000e+24
Name: mass, dtype: float64

…or using attribute syntax.

df.mass
Mercury    3.000000e+23
Venus      4.870000e+24
Earth      5.970000e+24
Name: mass, dtype: float64

Indexing works very similar to series

df.loc['Earth']
mass               5.970000e+24
diameter           1.275600e+07
rotation_period    2.390000e+01
Name: Earth, dtype: float64
df.iloc[2]
mass               5.970000e+24
diameter           1.275600e+07
rotation_period    2.390000e+01
Name: Earth, dtype: float64

But we can also specify the column we want to access

df.loc['Earth', 'mass']
5.97e+24
df.iloc[:2, 0]
Mercury    3.000000e+23
Venus      4.870000e+24
Name: mass, dtype: float64

If we make a calculation using columns from the DataFrame, it will keep the same index:

volume =  4/3 * np.pi * (df.diameter/2)**3
df.mass / volume
Mercury    4933.216530
Venus      5244.977070
Earth      5493.285577
dtype: float64

Which we can easily add as another column to the DataFrame:

df['density'] = df.mass / volume
df
mass diameter rotation_period density
Mercury 3.000000e+23 4879000.0 1407.6 4933.216530
Venus 4.870000e+24 12104000.0 NaN 5244.977070
Earth 5.970000e+24 12756000.0 23.9 5493.285577

Merging Data

Pandas supports a wide range of methods for merging different datasets. These are described extensively in the documentation. Here we just give a few examples.

temperature = pd.Series([167, 464, 15, -65],
                     index=['Mercury', 'Venus', 'Earth', 'Mars'],
                     name='temperature')
temperature
Mercury    167
Venus      464
Earth       15
Mars       -65
Name: temperature, dtype: int64
# returns a new DataFrame
df.join(temperature)
mass diameter rotation_period density temperature
Mercury 3.000000e+23 4879000.0 1407.6 4933.216530 167
Venus 4.870000e+24 12104000.0 NaN 5244.977070 464
Earth 5.970000e+24 12756000.0 23.9 5493.285577 15
# returns a new DataFrame
df.join(temperature, how='right')
mass diameter rotation_period density temperature
Mercury 3.000000e+23 4879000.0 1407.6 4933.216530 167
Venus 4.870000e+24 12104000.0 NaN 5244.977070 464
Earth 5.970000e+24 12756000.0 23.9 5493.285577 15
Mars NaN NaN NaN NaN -65
# returns a new DataFrame
everyone = df.reindex(['Mercury', 'Venus', 'Earth', 'Mars'])
everyone
mass diameter rotation_period density
Mercury 3.000000e+23 4879000.0 1407.6 4933.216530
Venus 4.870000e+24 12104000.0 NaN 5244.977070
Earth 5.970000e+24 12756000.0 23.9 5493.285577
Mars NaN NaN NaN NaN

We can also index using a boolean series. This is very useful

adults = df[df.mass > 4e24]
adults
mass diameter rotation_period density
Venus 4.870000e+24 12104000.0 NaN 5244.977070
Earth 5.970000e+24 12756000.0 23.9 5493.285577
df['is_big'] = df.mass > 4e24
df
mass diameter rotation_period density is_big
Mercury 3.000000e+23 4879000.0 1407.6 4933.216530 False
Venus 4.870000e+24 12104000.0 NaN 5244.977070 True
Earth 5.970000e+24 12756000.0 23.9 5493.285577 True

Modifying Values

We often want to modify values in a dataframe based on some rule. To modify values, we need to use .loc or .iloc

df.loc['Earth', 'mass'] = 5.98+24
df.loc['Venus', 'diameter'] += 1
df
mass diameter rotation_period density is_big
Mercury 3.000000e+23 4879000.0 1407.6 4933.216530 False
Venus 4.870000e+24 12104001.0 NaN 5244.977070 True
Earth 2.998000e+01 12756000.0 23.9 5493.285577 True

Plotting

DataFrames have all kinds of useful plotting built in.

df.plot(kind='scatter', x='mass', y='diameter', grid=True)
<AxesSubplot:xlabel='mass', ylabel='diameter'>
../../_images/basic_pandas_56_1.png
df.plot(kind='bar')
<AxesSubplot:>
../../_images/basic_pandas_57_1.png

Time Indexes

Indexes are very powerful. They are a big part of why Pandas is so useful. There are different indices for different types of data. Time Indexes are especially great!

two_years = pd.date_range(start='2014-01-01', end='2016-01-01', freq='D')
timeseries = pd.Series(np.sin(2 *np.pi *two_years.dayofyear / 365),
                       index=two_years)
timeseries.plot()
<AxesSubplot:>
../../_images/basic_pandas_59_1.png

We can use python’s slicing notation inside .loc to select a date range.

timeseries.loc['2015-01-01':'2015-07-01'].plot()
<AxesSubplot:>
../../_images/basic_pandas_61_1.png

The TimeIndex object has lots of useful attributes

timeseries.index.month
Int64Index([ 1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
            ...
            12, 12, 12, 12, 12, 12, 12, 12, 12,  1],
           dtype='int64', length=731)
timeseries.index.day
Int64Index([ 1,  2,  3,  4,  5,  6,  7,  8,  9, 10,
            ...
            23, 24, 25, 26, 27, 28, 29, 30, 31,  1],
           dtype='int64', length=731)

Reading Data Files: Weather Station Data

In this example, we will use NOAA weather station data from https://www.ncdc.noaa.gov/data-access/land-based-station-data.

The details of files we are going to read are described in this README file.

import pooch
POOCH = pooch.create(
    path=pooch.os_cache("noaa-data"),
    base_url="doi:10.5281/zenodo.5564850/",
    registry={
        "data.txt": "md5:5129dcfd19300eb8d4d8d1673fcfbcb4",
    },
)
datafile = POOCH.fetch("data.txt")
datafile
'/home/jovyan/.cache/noaa-data/data.txt'
! head '/home/jovyan/.cache/noaa-data/data.txt'
WBANNO LST_DATE CRX_VN LONGITUDE LATITUDE T_DAILY_MAX T_DAILY_MIN T_DAILY_MEAN T_DAILY_AVG P_DAILY_CALC SOLARAD_DAILY SUR_TEMP_DAILY_TYPE SUR_TEMP_DAILY_MAX SUR_TEMP_DAILY_MIN SUR_TEMP_DAILY_AVG RH_DAILY_MAX RH_DAILY_MIN RH_DAILY_AVG SOIL_MOISTURE_5_DAILY SOIL_MOISTURE_10_DAILY SOIL_MOISTURE_20_DAILY SOIL_MOISTURE_50_DAILY SOIL_MOISTURE_100_DAILY SOIL_TEMP_5_DAILY SOIL_TEMP_10_DAILY SOIL_TEMP_20_DAILY SOIL_TEMP_50_DAILY SOIL_TEMP_100_DAILY 
64756 20170101  2.422  -73.74   41.79     6.6    -5.4     0.6     2.2     0.0     8.68 C     7.9    -6.6    -0.5    84.8    30.7    53.7 -99.000 -99.000   0.207   0.152   0.175    -0.1     0.0     0.6     1.5     3.4
64756 20170102  2.422  -73.74   41.79     4.0    -6.8    -1.4    -1.2     0.0     2.08 C     4.1    -7.1    -1.6    91.1    49.1    77.4 -99.000 -99.000   0.205   0.151   0.173    -0.2     0.0     0.6     1.5     3.3
64756 20170103  2.422  -73.74   41.79     4.9     0.7     2.8     2.7    13.1     0.68 C     3.9     0.1     1.6    96.5    80.1    91.5 -99.000 -99.000   0.205   0.150   0.173    -0.1     0.0     0.5     1.5     3.3
64756 20170104  2.422  -73.74   41.79     8.7    -1.6     3.6     3.5     1.3     2.85 C     9.4    -4.5     1.3    97.4    34.0    73.1 -99.000 -99.000   0.215   0.153   0.174    -0.1     0.0     0.5     1.5     3.2
64756 20170105  2.422  -73.74   41.79    -0.5    -4.6    -2.5    -2.8     0.0     4.90 C     5.0    -7.6    -3.3    51.0    34.4    42.5 -99.000 -99.000   0.215   0.154   0.177    -0.1     0.0     0.5     1.4     3.1
64756 20170106  2.422  -73.74   41.79    -2.5   -10.1    -6.3    -4.7     1.3     5.17 C     1.8   -12.9    -5.2    89.8    40.0    60.8 -99.000 -99.000   0.210   0.153   0.177    -0.2     0.0     0.5     1.4     3.1
64756 20170107  2.422  -73.74   41.79    -7.3   -11.7    -9.5    -8.7     3.1     1.19 C    -5.0   -19.0    -8.5    84.4    50.9    71.2 -99.000 -99.000   0.204   0.152   0.175    -0.4    -0.1     0.5     1.4     3.0
64756 20170108  2.422  -73.74   41.79    -5.9   -14.5   -10.2    -9.4     0.0     6.15 C    -5.5   -23.1   -14.0    76.9    40.3    59.8 -99.000 -99.000   0.206   0.150   0.175    -0.4    -0.2     0.4     1.4     3.0
64756 20170109  2.422  -73.74   41.79    -6.5   -20.2   -13.3   -12.5     0.0     5.86 C    -6.4   -23.4   -16.2    82.5    45.1    65.8 -99.000 -99.000   0.223   0.148   0.175    -0.7    -0.4     0.4     1.3     3.0

We now have a text file on our hard drive called data.txt. Examine it.

To read it into pandas, we will use the read_csv function. This function is incredibly complex and powerful. You can use it to extract data from almost any text file. However, you need to understand how to use its various options.

With no options, this is what we get.

df = pd.read_csv(datafile)
df.head()
WBANNO LST_DATE CRX_VN LONGITUDE LATITUDE T_DAILY_MAX T_DAILY_MIN T_DAILY_MEAN T_DAILY_AVG P_DAILY_CALC SOLARAD_DAILY SUR_TEMP_DAILY_TYPE SUR_TEMP_DAILY_MAX SUR_TEMP_DAILY_MIN SUR_TEMP_DAILY_AVG RH_DAILY_MAX RH_DAILY_MIN RH_DAILY_AVG SOIL_MOISTURE_5_DAILY SOIL_MOISTURE_10_DAILY SOIL_MOISTURE_20_DAILY SOIL_MOISTURE_50_DAILY SOIL_MOISTURE_100_DAILY SOIL_TEMP_5_DAILY SOIL_TEMP_10_DAILY SOIL_TEMP_20_DAILY SOIL_TEMP_50_DAILY SOIL_TEMP_100_DAILY
0 64756 20170101 2.422 -73.74 41.79 6.6 ...
1 64756 20170102 2.422 -73.74 41.79 4.0 ...
2 64756 20170103 2.422 -73.74 41.79 4.9 ...
3 64756 20170104 2.422 -73.74 41.79 8.7 ...
4 64756 20170105 2.422 -73.74 41.79 -0.5 ...

Pandas failed to identify the different columns. This is because it was expecting standard CSV (comma-separated values) file. In our file, instead, the values are separated by whitespace. And not a single whilespace–the amount of whitespace between values varies. We can tell pandas this using the sep keyword.

df = pd.read_csv(datafile, sep='\s+')
df.head()
WBANNO LST_DATE CRX_VN LONGITUDE LATITUDE T_DAILY_MAX T_DAILY_MIN T_DAILY_MEAN T_DAILY_AVG P_DAILY_CALC ... SOIL_MOISTURE_5_DAILY SOIL_MOISTURE_10_DAILY SOIL_MOISTURE_20_DAILY SOIL_MOISTURE_50_DAILY SOIL_MOISTURE_100_DAILY SOIL_TEMP_5_DAILY SOIL_TEMP_10_DAILY SOIL_TEMP_20_DAILY SOIL_TEMP_50_DAILY SOIL_TEMP_100_DAILY
0 64756 20170101 2.422 -73.74 41.79 6.6 -5.4 0.6 2.2 0.0 ... -99.0 -99.0 0.207 0.152 0.175 -0.1 0.0 0.6 1.5 3.4
1 64756 20170102 2.422 -73.74 41.79 4.0 -6.8 -1.4 -1.2 0.0 ... -99.0 -99.0 0.205 0.151 0.173 -0.2 0.0 0.6 1.5 3.3
2 64756 20170103 2.422 -73.74 41.79 4.9 0.7 2.8 2.7 13.1 ... -99.0 -99.0 0.205 0.150 0.173 -0.1 0.0 0.5 1.5 3.3
3 64756 20170104 2.422 -73.74 41.79 8.7 -1.6 3.6 3.5 1.3 ... -99.0 -99.0 0.215 0.153 0.174 -0.1 0.0 0.5 1.5 3.2
4 64756 20170105 2.422 -73.74 41.79 -0.5 -4.6 -2.5 -2.8 0.0 ... -99.0 -99.0 0.215 0.154 0.177 -0.1 0.0 0.5 1.4 3.1

5 rows × 28 columns

Great! It worked.

If we look closely, we will see there are lots of -99 and -9999 values in the file. The README file tells us that these are values used to represent missing data. Let’s tell this to pandas.

df = pd.read_csv(datafile, sep='\s+', na_values=[-9999.0, -99.0])
df.head()
WBANNO LST_DATE CRX_VN LONGITUDE LATITUDE T_DAILY_MAX T_DAILY_MIN T_DAILY_MEAN T_DAILY_AVG P_DAILY_CALC ... SOIL_MOISTURE_5_DAILY SOIL_MOISTURE_10_DAILY SOIL_MOISTURE_20_DAILY SOIL_MOISTURE_50_DAILY SOIL_MOISTURE_100_DAILY SOIL_TEMP_5_DAILY SOIL_TEMP_10_DAILY SOIL_TEMP_20_DAILY SOIL_TEMP_50_DAILY SOIL_TEMP_100_DAILY
0 64756 20170101 2.422 -73.74 41.79 6.6 -5.4 0.6 2.2 0.0 ... NaN NaN 0.207 0.152 0.175 -0.1 0.0 0.6 1.5 3.4
1 64756 20170102 2.422 -73.74 41.79 4.0 -6.8 -1.4 -1.2 0.0 ... NaN NaN 0.205 0.151 0.173 -0.2 0.0 0.6 1.5 3.3
2 64756 20170103 2.422 -73.74 41.79 4.9 0.7 2.8 2.7 13.1 ... NaN NaN 0.205 0.150 0.173 -0.1 0.0 0.5 1.5 3.3
3 64756 20170104 2.422 -73.74 41.79 8.7 -1.6 3.6 3.5 1.3 ... NaN NaN 0.215 0.153 0.174 -0.1 0.0 0.5 1.5 3.2
4 64756 20170105 2.422 -73.74 41.79 -0.5 -4.6 -2.5 -2.8 0.0 ... NaN NaN 0.215 0.154 0.177 -0.1 0.0 0.5 1.4 3.1

5 rows × 28 columns

Great. The missing data is now represented by NaN.

What data types did pandas infer?

df.info()
<class 'pandas.core.frame.DataFrame'>
RangeIndex: 365 entries, 0 to 364
Data columns (total 28 columns):
 #   Column                   Non-Null Count  Dtype  
---  ------                   --------------  -----  
 0   WBANNO                   365 non-null    int64  
 1   LST_DATE                 365 non-null    int64  
 2   CRX_VN                   365 non-null    float64
 3   LONGITUDE                365 non-null    float64
 4   LATITUDE                 365 non-null    float64
 5   T_DAILY_MAX              364 non-null    float64
 6   T_DAILY_MIN              364 non-null    float64
 7   T_DAILY_MEAN             364 non-null    float64
 8   T_DAILY_AVG              364 non-null    float64
 9   P_DAILY_CALC             364 non-null    float64
 10  SOLARAD_DAILY            364 non-null    float64
 11  SUR_TEMP_DAILY_TYPE      365 non-null    object 
 12  SUR_TEMP_DAILY_MAX       364 non-null    float64
 13  SUR_TEMP_DAILY_MIN       364 non-null    float64
 14  SUR_TEMP_DAILY_AVG       364 non-null    float64
 15  RH_DAILY_MAX             364 non-null    float64
 16  RH_DAILY_MIN             364 non-null    float64
 17  RH_DAILY_AVG             364 non-null    float64
 18  SOIL_MOISTURE_5_DAILY    317 non-null    float64
 19  SOIL_MOISTURE_10_DAILY   317 non-null    float64
 20  SOIL_MOISTURE_20_DAILY   336 non-null    float64
 21  SOIL_MOISTURE_50_DAILY   364 non-null    float64
 22  SOIL_MOISTURE_100_DAILY  359 non-null    float64
 23  SOIL_TEMP_5_DAILY        364 non-null    float64
 24  SOIL_TEMP_10_DAILY       364 non-null    float64
 25  SOIL_TEMP_20_DAILY       364 non-null    float64
 26  SOIL_TEMP_50_DAILY       364 non-null    float64
 27  SOIL_TEMP_100_DAILY      364 non-null    float64
dtypes: float64(25), int64(2), object(1)
memory usage: 80.0+ KB

One problem here is that pandas did not recognize the LDT_DATE column as a date. Let’s help it.

df = pd.read_csv(datafile, sep='\s+',
                 na_values=[-9999.0, -99.0],
                 parse_dates=[1])
df.info()
<class 'pandas.core.frame.DataFrame'>
RangeIndex: 365 entries, 0 to 364
Data columns (total 28 columns):
 #   Column                   Non-Null Count  Dtype         
---  ------                   --------------  -----         
 0   WBANNO                   365 non-null    int64         
 1   LST_DATE                 365 non-null    datetime64[ns]
 2   CRX_VN                   365 non-null    float64       
 3   LONGITUDE                365 non-null    float64       
 4   LATITUDE                 365 non-null    float64       
 5   T_DAILY_MAX              364 non-null    float64       
 6   T_DAILY_MIN              364 non-null    float64       
 7   T_DAILY_MEAN             364 non-null    float64       
 8   T_DAILY_AVG              364 non-null    float64       
 9   P_DAILY_CALC             364 non-null    float64       
 10  SOLARAD_DAILY            364 non-null    float64       
 11  SUR_TEMP_DAILY_TYPE      365 non-null    object        
 12  SUR_TEMP_DAILY_MAX       364 non-null    float64       
 13  SUR_TEMP_DAILY_MIN       364 non-null    float64       
 14  SUR_TEMP_DAILY_AVG       364 non-null    float64       
 15  RH_DAILY_MAX             364 non-null    float64       
 16  RH_DAILY_MIN             364 non-null    float64       
 17  RH_DAILY_AVG             364 non-null    float64       
 18  SOIL_MOISTURE_5_DAILY    317 non-null    float64       
 19  SOIL_MOISTURE_10_DAILY   317 non-null    float64       
 20  SOIL_MOISTURE_20_DAILY   336 non-null    float64       
 21  SOIL_MOISTURE_50_DAILY   364 non-null    float64       
 22  SOIL_MOISTURE_100_DAILY  359 non-null    float64       
 23  SOIL_TEMP_5_DAILY        364 non-null    float64       
 24  SOIL_TEMP_10_DAILY       364 non-null    float64       
 25  SOIL_TEMP_20_DAILY       364 non-null    float64       
 26  SOIL_TEMP_50_DAILY       364 non-null    float64       
 27  SOIL_TEMP_100_DAILY      364 non-null    float64       
dtypes: datetime64[ns](1), float64(25), int64(1), object(1)
memory usage: 80.0+ KB

It worked! Finally, let’s tell pandas to use the date column as the index.

df = df.set_index('LST_DATE')
df.head()
WBANNO CRX_VN LONGITUDE LATITUDE T_DAILY_MAX T_DAILY_MIN T_DAILY_MEAN T_DAILY_AVG P_DAILY_CALC SOLARAD_DAILY ... SOIL_MOISTURE_5_DAILY SOIL_MOISTURE_10_DAILY SOIL_MOISTURE_20_DAILY SOIL_MOISTURE_50_DAILY SOIL_MOISTURE_100_DAILY SOIL_TEMP_5_DAILY SOIL_TEMP_10_DAILY SOIL_TEMP_20_DAILY SOIL_TEMP_50_DAILY SOIL_TEMP_100_DAILY
LST_DATE
2017-01-01 64756 2.422 -73.74 41.79 6.6 -5.4 0.6 2.2 0.0 8.68 ... NaN NaN 0.207 0.152 0.175 -0.1 0.0 0.6 1.5 3.4
2017-01-02 64756 2.422 -73.74 41.79 4.0 -6.8 -1.4 -1.2 0.0 2.08 ... NaN NaN 0.205 0.151 0.173 -0.2 0.0 0.6 1.5 3.3
2017-01-03 64756 2.422 -73.74 41.79 4.9 0.7 2.8 2.7 13.1 0.68 ... NaN NaN 0.205 0.150 0.173 -0.1 0.0 0.5 1.5 3.3
2017-01-04 64756 2.422 -73.74 41.79 8.7 -1.6 3.6 3.5 1.3 2.85 ... NaN NaN 0.215 0.153 0.174 -0.1 0.0 0.5 1.5 3.2
2017-01-05 64756 2.422 -73.74 41.79 -0.5 -4.6 -2.5 -2.8 0.0 4.90 ... NaN NaN 0.215 0.154 0.177 -0.1 0.0 0.5 1.4 3.1

5 rows × 27 columns

We can now access values by time:

df.loc['2017-08-07']
WBANNO                     64756
CRX_VN                     2.422
LONGITUDE                 -73.74
LATITUDE                   41.79
T_DAILY_MAX                 19.3
T_DAILY_MIN                 12.3
T_DAILY_MEAN                15.8
T_DAILY_AVG                 16.3
P_DAILY_CALC                 4.9
SOLARAD_DAILY               3.93
SUR_TEMP_DAILY_TYPE            C
SUR_TEMP_DAILY_MAX          22.3
SUR_TEMP_DAILY_MIN          11.9
SUR_TEMP_DAILY_AVG          17.7
RH_DAILY_MAX                94.7
RH_DAILY_MIN                76.4
RH_DAILY_AVG                89.5
SOIL_MOISTURE_5_DAILY      0.148
SOIL_MOISTURE_10_DAILY     0.113
SOIL_MOISTURE_20_DAILY     0.094
SOIL_MOISTURE_50_DAILY     0.114
SOIL_MOISTURE_100_DAILY    0.151
SOIL_TEMP_5_DAILY           21.4
SOIL_TEMP_10_DAILY          21.7
SOIL_TEMP_20_DAILY          22.1
SOIL_TEMP_50_DAILY          22.2
SOIL_TEMP_100_DAILY         21.5
Name: 2017-08-07 00:00:00, dtype: object

Or use slicing to get a range:

df.loc['2017-07-01':'2017-07-31']
WBANNO CRX_VN LONGITUDE LATITUDE T_DAILY_MAX T_DAILY_MIN T_DAILY_MEAN T_DAILY_AVG P_DAILY_CALC SOLARAD_DAILY ... SOIL_MOISTURE_5_DAILY SOIL_MOISTURE_10_DAILY SOIL_MOISTURE_20_DAILY SOIL_MOISTURE_50_DAILY SOIL_MOISTURE_100_DAILY SOIL_TEMP_5_DAILY SOIL_TEMP_10_DAILY SOIL_TEMP_20_DAILY SOIL_TEMP_50_DAILY SOIL_TEMP_100_DAILY
LST_DATE
2017-07-01 64756 2.422 -73.74 41.79 28.0 19.7 23.9 23.8 0.2 19.28 ... 0.157 0.136 0.144 0.129 0.163 25.7 25.4 23.7 21.9 19.9
2017-07-02 64756 2.422 -73.74 41.79 29.8 18.4 24.1 23.7 4.0 27.67 ... 0.146 0.135 0.143 0.129 0.162 26.8 26.4 24.5 22.3 20.1
2017-07-03 64756 2.422 -73.74 41.79 28.3 15.0 21.7 21.4 0.0 27.08 ... 0.141 0.132 0.139 0.128 0.162 26.4 26.3 24.8 22.8 20.3
2017-07-04 64756 2.422 -73.74 41.79 26.8 12.6 19.7 20.0 0.0 29.45 ... 0.131 0.126 0.136 0.126 0.161 25.9 25.8 24.6 22.9 20.6
2017-07-05 64756 2.422 -73.74 41.79 28.0 11.9 20.0 20.7 0.0 26.90 ... 0.116 0.114 0.131 0.125 0.161 25.3 25.3 24.2 22.8 20.7
2017-07-06 64756 2.422 -73.74 41.79 25.7 14.3 20.0 20.3 0.0 19.03 ... 0.105 0.104 0.126 0.124 0.160 24.7 24.7 23.9 22.7 20.9
2017-07-07 64756 2.422 -73.74 41.79 25.8 16.8 21.3 20.0 11.5 13.88 ... 0.114 0.100 0.123 0.123 0.160 24.2 24.2 23.4 22.4 20.8
2017-07-08 64756 2.422 -73.74 41.79 29.0 15.3 22.1 21.5 0.0 21.92 ... 0.130 0.106 0.122 0.123 0.159 25.5 25.3 23.9 22.4 20.8
2017-07-09 64756 2.422 -73.74 41.79 26.3 10.9 18.6 19.4 0.0 29.72 ... 0.119 0.103 0.119 0.121 0.158 24.8 24.8 23.8 22.5 20.8
2017-07-10 64756 2.422 -73.74 41.79 27.6 11.8 19.7 21.3 0.0 23.67 ... 0.105 0.096 0.113 0.120 0.158 24.7 24.7 23.6 22.5 20.9
2017-07-11 64756 2.422 -73.74 41.79 27.4 19.2 23.3 22.6 8.5 17.79 ... 0.106 0.093 0.110 0.120 0.157 25.6 25.4 24.1 22.6 20.9
2017-07-12 64756 2.422 -73.74 41.79 29.4 18.5 23.9 23.1 1.9 16.27 ... 0.108 0.094 0.108 0.118 0.157 25.8 25.6 24.2 22.8 21.0
2017-07-13 64756 2.422 -73.74 41.79 29.5 18.3 23.9 23.4 23.3 13.61 ... 0.134 0.110 0.108 0.118 0.156 25.7 25.7 24.4 23.0 21.0
2017-07-14 64756 2.422 -73.74 41.79 18.5 15.9 17.2 17.5 4.1 5.36 ... 0.194 0.151 0.114 0.120 0.155 23.0 23.3 23.4 22.9 21.2
2017-07-15 64756 2.422 -73.74 41.79 26.6 16.5 21.5 21.0 0.8 21.13 ... 0.190 0.163 0.119 0.122 0.155 24.6 24.4 23.2 22.2 21.2
2017-07-16 64756 2.422 -73.74 41.79 27.9 13.3 20.6 21.0 0.0 27.03 ... 0.171 0.154 0.123 0.123 0.155 25.4 25.3 23.9 22.6 21.1
2017-07-17 64756 2.422 -73.74 41.79 29.2 16.1 22.6 22.9 0.0 20.47 ... 0.155 0.143 0.124 0.122 0.156 25.7 25.6 24.4 22.9 21.2
2017-07-18 64756 2.422 -73.74 41.79 30.3 19.3 24.8 24.7 0.0 24.99 ... 0.142 0.132 0.122 0.122 0.156 27.0 26.7 24.9 23.2 21.3
2017-07-19 64756 2.422 -73.74 41.79 31.2 19.1 25.1 25.0 0.0 27.69 ... 0.126 0.118 0.118 0.122 0.156 27.6 27.4 25.6 23.7 21.5
2017-07-20 64756 2.422 -73.74 41.79 31.8 16.6 24.2 23.4 0.7 21.53 ... 0.111 0.103 0.114 0.121 0.156 27.0 27.0 25.6 24.0 21.7
2017-07-21 64756 2.422 -73.74 41.79 30.6 16.6 23.6 23.6 0.0 25.55 ... 0.100 0.093 0.108 0.120 0.155 27.1 27.0 25.5 24.0 21.9
2017-07-22 64756 2.422 -73.74 41.79 27.7 15.6 21.7 21.2 0.5 16.04 ... 0.092 0.086 0.104 0.119 0.156 25.9 26.1 25.3 24.1 22.0
2017-07-23 64756 2.422 -73.74 41.79 26.4 18.5 22.5 22.2 0.0 19.03 ... 0.087 0.082 0.100 0.118 0.155 26.0 26.0 24.9 23.8 22.1
2017-07-24 64756 2.422 -73.74 41.79 19.4 14.8 17.1 16.7 29.2 9.10 ... 0.145 0.118 0.102 0.117 0.154 23.1 23.6 23.9 23.5 22.1
2017-07-25 64756 2.422 -73.74 41.79 18.6 13.7 16.2 16.2 0.0 7.35 ... 0.167 0.133 0.107 0.116 0.153 21.9 22.2 22.4 22.5 21.9
2017-07-26 64756 2.422 -73.74 41.79 24.7 11.2 18.0 18.3 0.0 22.22 ... 0.155 0.128 0.108 0.118 0.152 22.9 23.0 22.3 22.0 21.7
2017-07-27 64756 2.422 -73.74 41.79 24.2 15.2 19.7 19.5 0.0 8.28 ... 0.144 0.122 0.109 0.118 0.154 22.5 22.7 22.4 22.0 21.4
2017-07-28 64756 2.422 -73.74 41.79 26.5 16.9 21.7 20.9 0.0 21.06 ... 0.137 0.117 0.110 0.119 0.154 24.1 24.1 22.8 22.0 21.3
2017-07-29 64756 2.422 -73.74 41.79 24.2 10.4 17.3 18.1 0.0 21.28 ... 0.126 0.108 0.108 0.118 0.154 23.3 23.6 23.0 22.2 21.3
2017-07-30 64756 2.422 -73.74 41.79 25.5 8.2 16.8 17.3 0.0 27.68 ... 0.113 0.099 0.104 0.117 0.154 22.8 23.0 22.4 22.0 21.3
2017-07-31 64756 2.422 -73.74 41.79 29.4 10.1 19.7 20.1 0.0 25.49 ... 0.101 0.090 0.099 0.116 0.153 23.8 23.8 22.7 21.9 21.2

31 rows × 27 columns

Quick Statistics

df.describe()
WBANNO CRX_VN LONGITUDE LATITUDE T_DAILY_MAX T_DAILY_MIN T_DAILY_MEAN T_DAILY_AVG P_DAILY_CALC SOLARAD_DAILY ... SOIL_MOISTURE_5_DAILY SOIL_MOISTURE_10_DAILY SOIL_MOISTURE_20_DAILY SOIL_MOISTURE_50_DAILY SOIL_MOISTURE_100_DAILY SOIL_TEMP_5_DAILY SOIL_TEMP_10_DAILY SOIL_TEMP_20_DAILY SOIL_TEMP_50_DAILY SOIL_TEMP_100_DAILY
count 365.0 365.000000 3.650000e+02 3.650000e+02 364.000000 364.000000 364.000000 364.000000 364.000000 364.000000 ... 317.000000 317.000000 336.000000 364.000000 359.000000 364.000000 364.000000 364.000000 364.000000 364.000000
mean 64756.0 2.470767 -7.374000e+01 4.179000e+01 15.720055 4.037912 9.876374 9.990110 2.797802 13.068187 ... 0.189498 0.183991 0.165470 0.140192 0.160630 12.312637 12.320604 12.060165 11.978022 11.915659
std 0.0 0.085997 5.265234e-13 3.842198e-13 10.502087 9.460676 9.727451 9.619168 7.238628 7.953074 ... 0.052031 0.054113 0.043989 0.020495 0.016011 9.390034 9.338176 8.767752 8.078346 7.187317
min 64756.0 2.422000 -7.374000e+01 4.179000e+01 -12.300000 -21.800000 -17.000000 -16.700000 0.000000 0.100000 ... 0.075000 0.078000 0.087000 0.101000 0.117000 -0.700000 -0.400000 0.200000 0.900000 1.900000
25% 64756.0 2.422000 -7.374000e+01 4.179000e+01 6.900000 -2.775000 2.100000 2.275000 0.000000 6.225000 ... 0.152000 0.139000 0.118750 0.118000 0.154000 2.225000 2.000000 2.475000 3.300000 4.100000
50% 64756.0 2.422000 -7.374000e+01 4.179000e+01 17.450000 4.350000 10.850000 11.050000 0.000000 12.865000 ... 0.192000 0.198000 0.183000 0.147500 0.165000 13.300000 13.350000 13.100000 12.850000 11.600000
75% 64756.0 2.422000 -7.374000e+01 4.179000e+01 24.850000 11.900000 18.150000 18.450000 1.400000 19.740000 ... 0.234000 0.227000 0.203000 0.157000 0.173000 21.025000 21.125000 20.400000 19.800000 19.325000
max 64756.0 2.622000 -7.374000e+01 4.179000e+01 33.400000 20.700000 25.700000 26.700000 65.700000 29.910000 ... 0.296000 0.321000 0.235000 0.182000 0.192000 27.600000 27.400000 25.600000 24.100000 22.100000

8 rows × 26 columns

Plotting Values

We can now quickly make plots of the data

fig, ax = plt.subplots(ncols=2, nrows=2, figsize=(14,14))

df.iloc[:, 4:8].boxplot(ax=ax[0,0])
df.iloc[:, 10:14].boxplot(ax=ax[0,1])
df.iloc[:, 14:17].boxplot(ax=ax[1,0])
df.iloc[:, 18:22].boxplot(ax=ax[1,1])


ax[1, 1].set_xticklabels(ax[1, 1].get_xticklabels(), rotation=90);
../../_images/basic_pandas_87_0.png

Pandas is very “time aware”:

df.T_DAILY_MEAN.plot()
<AxesSubplot:xlabel='LST_DATE'>
../../_images/basic_pandas_89_1.png

Note: we could also manually create an axis and plot into it.

fig, ax = plt.subplots()
df.T_DAILY_MEAN.plot(ax=ax)
ax.set_title('Pandas Made This!')
Text(0.5, 1.0, 'Pandas Made This!')
../../_images/basic_pandas_91_1.png
df[['T_DAILY_MIN', 'T_DAILY_MEAN', 'T_DAILY_MAX']].plot()
<AxesSubplot:xlabel='LST_DATE'>
../../_images/basic_pandas_92_1.png

Resampling

Since pandas understands time, we can use it to do resampling.

# monthly reampler object
rs_obj = df.resample('MS')
rs_obj
<pandas.core.resample.DatetimeIndexResampler object at 0x7f1f14a1d5e0>
rs_obj.mean()
WBANNO CRX_VN LONGITUDE LATITUDE T_DAILY_MAX T_DAILY_MIN T_DAILY_MEAN T_DAILY_AVG P_DAILY_CALC SOLARAD_DAILY ... SOIL_MOISTURE_5_DAILY SOIL_MOISTURE_10_DAILY SOIL_MOISTURE_20_DAILY SOIL_MOISTURE_50_DAILY SOIL_MOISTURE_100_DAILY SOIL_TEMP_5_DAILY SOIL_TEMP_10_DAILY SOIL_TEMP_20_DAILY SOIL_TEMP_50_DAILY SOIL_TEMP_100_DAILY
LST_DATE
2017-01-01 64756.0 2.422000 -73.74 41.79 3.945161 -3.993548 -0.025806 0.038710 3.090323 4.690000 ... 0.236900 0.248300 0.204550 0.152806 0.175194 0.209677 0.267742 0.696774 1.438710 2.877419
2017-02-01 64756.0 2.422000 -73.74 41.79 7.246429 -4.360714 1.442857 1.839286 2.414286 10.364286 ... 0.226333 0.243000 0.207545 0.152857 0.175786 1.125000 1.100000 1.192857 1.492857 2.367857
2017-03-01 64756.0 2.422000 -73.74 41.79 5.164516 -5.335484 -0.090323 0.167742 3.970968 13.113548 ... 0.218033 0.229267 0.196258 0.153484 0.174548 2.122581 2.161290 2.345161 2.700000 3.387097
2017-04-01 64756.0 2.422000 -73.74 41.79 17.813333 5.170000 11.493333 11.540000 2.300000 14.645000 ... 0.199733 0.210300 0.190667 0.151000 0.172400 11.066667 10.666667 9.636667 8.426667 6.903333
2017-05-01 64756.0 2.422000 -73.74 41.79 19.151613 7.338710 13.229032 13.638710 4.141935 16.519677 ... 0.206613 0.210935 0.185613 0.147710 0.170000 16.454839 16.290323 15.361290 14.270968 12.696774
2017-06-01 64756.0 2.422000 -73.74 41.79 25.423333 12.176667 18.796667 18.986667 3.743333 21.655000 ... 0.185167 0.184300 0.173167 0.142533 0.167000 22.350000 22.166667 20.880000 19.370000 17.333333
2017-07-01 64756.0 2.422000 -73.74 41.79 26.912903 15.183871 21.048387 20.993548 2.732258 20.566129 ... 0.131226 0.115774 0.116613 0.121032 0.156677 24.993548 24.980645 23.925806 22.745161 21.164516
2017-08-01 64756.0 2.422000 -73.74 41.79 25.741935 12.954839 19.351613 19.477419 2.758065 18.360000 ... 0.143871 0.122258 0.105452 0.115290 0.151034 23.374194 23.519355 22.848387 22.193548 21.377419
2017-09-01 64756.0 2.422000 -73.74 41.79 24.186667 11.300000 17.746667 17.463333 1.893333 15.154667 ... 0.145167 0.139633 0.117267 0.112167 0.141926 20.256667 20.386667 19.966667 19.766667 19.530000
2017-10-01 64756.0 2.602645 -73.74 41.79 21.043333 7.150000 14.100000 13.976667 3.500000 10.395000 ... 0.151767 0.137767 0.111900 0.108900 0.122067 16.086667 16.193333 16.370000 16.893333 17.386667
2017-11-01 64756.0 2.622000 -73.74 41.79 10.346667 -2.093333 4.120000 4.336667 0.826667 6.723333 ... 0.241633 0.224467 0.203367 0.159500 0.155233 7.056667 7.273333 8.043333 9.633333 11.440000
2017-12-01 64756.0 2.622000 -73.74 41.79 1.496774 -7.412903 -2.967742 -2.838710 2.109677 4.474194 ... 0.255929 0.239071 0.213258 0.165387 0.163290 2.064516 2.241935 2.874194 4.248387 6.019355

12 rows × 26 columns

We can chain all of that together

df_mm = df.resample('MS').mean()
df_mm[['T_DAILY_MIN', 'T_DAILY_MEAN', 'T_DAILY_MAX']].plot()
<AxesSubplot:xlabel='LST_DATE'>
../../_images/basic_pandas_97_1.png

Next time we will dig deeper into resampling, rolling means, and grouping operations (groupby).