Python: Pandas library

read_csv()

read CSV file into DataFrame

read_excel()

read Excel file

read_sql()

read from SQL database

read_json()

read JSON file

read_html()

read HTML tables

read_clipboard()

read data from clipboard

read_parquet()

read Parquet file

read_feather()

read Feather file

read_orc()

read ORC file

read_hdf()

read HDF5 file

read_sas()

read SAS file

read_stata()

read Stata file

read_xml()

read XML data

to_datetime()

convert to datetime

to_numeric()

convert to numeric

to_timedelta()

convert to timedelta

concat()

concatenate DataFrames/Series

merge()

merge/join DataFrames

join()

join DataFrames by index

crosstab()

cross-tabulation of two factors

pivot()

create pivot table

pivot_table()

create pivot table with aggregation

melt()

unpivot a DataFrame

get_dummies()

convert categorical variables to dummy indicators

isna() / isnull()

detect missing values

notna() / notnull()

detect non-missing values

cut()

bin values into discrete intervals

qcut()

quantile-based discretization

unique()

return unique values

value_counts()

count occurrences of unique values

date_range()

create a range of dates

bdate_range()

business date range

period_range()

range of periods

interval_range()

range of intervals

index

row labels

columns

column labels

dtypes

data types of columns

shape

(rows, columns)

size

total elements

ndim

number of dimensions (always 2)

axes

list of row and column indexes

values

Numpy representation of data

head()

return first n rows

tail()

return last n rows

info()

summary of DataFrame

describe()

statistical summary

sample()

random rows

loc[]

label-based selection

iloc[]

integer-location selection

at[]

single value by label

iat[]

single value by position

xs()

cross-section

assign()

assign new columns

drop()

drop rows or columns

dropna()

remove missing values

fillna()

fill missing values

replace()

replace values

rename()

rename labels

set_index()

set index

reset_index()

reset index

sort_index()

sort by index

sort_values()

sort by values

sum()

column/row sum

mean()

average

median()

median

std()

standard deviation

var()

variance

min()

minimum

max()

maximum

count()

count non-null values

mode()

most frequent value

cumsum()

cumulative sum

cumprod()

cumulative product

groupby()

group by values

agg()

aggregate using custom functions

transform()

apply function element-wise

merge()

merge DataFrames

join()

join on index

concat()

concatenate along axis

append()

append rows (deprecated, use concat)

rolling()

rolling window calculations

expanding()

expanding window calculations

ewm()

exponential weighted functions

lower()

lowercase

upper()

uppercase

len()

length of each string

contains()

check substring

replace()

string replacement

split()

split strings

strip()

trim whitespace

get()

get element at position

startswith() / endswith()

check start/end

year

extract year

month

extract month

day

extract day

weekday

day of week

hour / minute / second

extract time

date

extract date part

strftime()

format dates

to_period()

convert to Period