DataFrame operation

Arithmetic

• Object adder -series .add (value)
• Object subtraction -series .sub (value / object)

Logical operation symbol <,>, |, &

1. Logical operation symbol <,>, |, & - equivalent to the sql statement where
   • It is equivalent to the logic operation numpy
   • It returns a Boolean objects (series / df)
2. Logical operation function
   • df.query () - the equivalent of inquiry
   • series.isin (list) --- returns a Boolean series -sql in the in keyword

Statistics operation

describe ()
Comprehensive analysis: the ability to directly draw a lot of statistics, count, mean, std, min , max , etc.

# 计算平均值、标准差、最大值、最小值
data.describe()

Statistics function
min (minimum value), max (maximum), mean (average), median (median), var (variance), std (standard deviation), mode (a mode) Results

Time for a single function to statistics, the axes of these default or according to "columns" (axis = 0, default), if you want to row "index" to specify (axis = 1)

• df.max (axis = 0/1) 0- min sum row column 1-
• df.idxmax (axis = 0/1) - where the maximum value of the index

Cumulative statistical functions

• Observation of the original data is not readily observable information
• series.cumsum-- result is not a return value
  

Custom operation
df.apply (func, axis)

1. func- function
2. Calculation of the shaft axis designated

data[['open', 'close']].apply(lambda x: x.max() - x.min(), axis=0)

open     22.74
close    22.85
dtype: float64