基本上只与pandas中的Select first row in each GROUP BY group?相同。
org 100h
jmp start
;functions area
WindowColor Macro X1,Y1,X2,Y2,Color
Mov Ax,0600h
Mov Cl,X1
Mov Ch,Y1
Mov Dl,X2
Mov Dh,Y2
Mov Bh,Color
Int 10h
EndM
printstring Macro Adr
MOV DX, OFFSET Adr
MOV AH, 9
INT 21h
EndM
goto macro x,y
MOV DH, x ;ROW
MOV DL, y ;COLUMN
MOV AH, 02H
INT 10H
EndM
curser macro x,y
MOV DH, x ;ROW
MOV DL, y ;COLUMN
MOV AH, 02H
INT 10H
EndM
printpixel macro x,y,color,p
mov bh, p
mov cx, x
mov dx, y
mov al, color
mov ah, 0ch
int 10h
EndM
delay macro time
mov cx,time
mov dx,4240h
mov ah,086h
int 15h
EndM
;----------------------------------
print_batt PROC
PRINTBATT:
MOV DX, player1top
print:
INC player1count
printpixel 10, DX, 0100B,1
INC DX
INC player1count
CMP player1count, 150
JNE print
SUB player1count, 150
RET
print_batt ENDP
print_com PROC
MOV DX, comtop
printcompo:
INC comcount
printpixel 308, DX, 0001b,1
INC DX
INC comcount
CMP comcount, 150
JNE printcompo
SUB comcount, 150
RET
print_com ENDP
print_ball PROC
printpixel ballx, bally, 00000001b,3
DEC ballx
DEC bally
printpixel ballx, bally, 00000001b,3
INC ballx
printpixel ballx, bally, 00000001b,3
sub ballx, 2
DEC bally
printpixel ballx, bally, 00000001b,3
inc ballx
printpixel ballx, bally, 00000001b,3
inc ballx
printpixel ballx, bally, 00000001b,3
inc ballx
printpixel ballx, bally, 00000001b,3
printpixel ballx, bally, 00000001b,3
DEC bally
sub ballx, 2
printpixel ballx, bally, 00000001b,3
INC ballx
printpixel ballx, bally, 00000001b,3
DEC bally
DEC bally
printpixel ballx, bally, 00000001b ,3
RET
print_ball ENDP
clearscreen proc
MOV AL, 13H ;changes the num of pixels to 640X480 with 16 colors
MOV AH, 0
INT 10H
ret
clearscreen ENDP
reprint proc
call clearscreen
call print_batt
call print_com
ret
reprint ENDP
baseprint proc
mov base, 0
printbase:
printpixel base, 0, 2, 2
INC base
CMP base, 320
JNE printbase
mov base, 0
printdownbase:
printpixel base, 199, 2, 2
INC base
CMP base, 320
JNE printdownbase
mov base, 0
printleftbase:
printpixel 0, base, 2, 2
INC base
CMP base, 199
JNE printleftbase
mov base, 0
printrightbase:
printpixel 319, base, 2, 2
INC base
CMP base, 199
JNE printrightbase
ret
baseprint EndP
;-----------------------ball movement proc-------------------
;main move
balloop macro move
call move
CALL hitcheck
JMP checkahit
EndM
;LEFT UP
bdleftup PROC
call reprint
sub ballx, 14
dec bally
CALL print_ball
MOV lastaction, bdleftup
RET
bdleftup ENDP
bdleftupreverse proc
ADD ballx, 11
INC bally
RET
bdleftupreverse ENDP
;LEFT DOWN
bdleftdown PROC
call reprint
sub ballx, 11
ADD bally, 10
CALL print_ball
MOV lastaction, bdleftdown
RET
bdleftdown ENDP
bdleftdownreverse proc
ADD ballx, 11
DEC bally
RET
bdleftdownreverse ENDP
;RIGHT UP
bdrightup PROC
call reprint
ADD ballx, 11
DEC bally
CALL print_ball
MOV lastaction, bdrightup
RET
bdrightup ENDP
bdrightupreverse proc
SUB ballx, 11
INC bally
RET
bdrightupreverse ENDP
;RIGHT DOWN
bdrightdown PROC
call reprint
ADD ballx, 10
ADD bally, 11
CALL print_ball
MOV lastaction, bdrightdown
RET
bdrightdown ENDP
bdrightdownreverse proc
SUB ballx, 11
DEC bally
RET
bdrightdownreverse ENDP
hitcheck PROC
;------batt and com check-------
MOV BH, 2H
MOV DX, ballx
MOV CX, bally
SUB CX, 2
MOV AH, 0Dh
INT 10H
CMP AL, 1
JE hitmovement
CMP AL, 3
JE comhitmovement
MOV BH, 2H
MOV DX, ballx
MOV CX, bally
ADD CX, 2
MOV AH, 0Dh
INT 10H
CMP AL, 1
JE hitmovement
CMP AL, 3
JE comhitmovement
MOV BH, 2H
MOV DX, ballx
MOV CX, bally
SUB DX, 2
MOV AH, 0Dh
INT 10H
CMP AL, 1
JE hitmovement
CMP AL, 3
JE comhitmovement
MOV BH, 2H
MOV DX, ballx
MOV CX, bally
ADD DX, 2
MOV AH, 0Dh
INT 10H
CMP AL, 1
JE hitmovement
CMP AL, 3
JE comhitmovement
;------base check-------
CMP bally, 1
JB upbasehitmovement
JE upbasehitmovement
CMP ballx, 1
JB leftbasehitmovement
JE leftbasehitmovement
CMP bally, 199
JA downbasehitmovement
JE downbasehitmovement
CMP ballx, 315
JA rightbasehitmovement
JE rightbasehitmovement
JMP nonhit
hitmovement:
MOV AH, 2CH ;TIMER
INT 21H
CMP DH, 30
JA NC1
JB NC13
NC13:
balloop bdrightup ;BALLOOP CONFIGURATION
JMP checkahit
NC1:
balloop bdrightdown ;BALLOOP CONFIGURATION
JMP checkahit
comhitmovement:
MOV AH, 2CH ;TIMER
INT 21H
CMP DH, 30
JA NC2
balloop bdleftdown ;BALLOOP CONFIGURATION
NC2:
balloop bdleftup ;BALLOOP CONFIGURATION
JMP checkahit
upbasehitmovement:
balloop bdrightdown
JMP checkahit
downbasehitmovement:
balloop bdrightup
JMP checkahit
rightbasehitmovement:
JMP END
leftbasehitmovement:
JMP END
nonhit:
ret
hitcheck EndP
;----------------------------------data area-------------------------
yay DB " ,-.----. ,----.. ,--. ", 13, 10
DB " \ / \ / / \ ,--.'| ,----.. ", 13, 10
DB " | : \ / . : ,--,: : | / / \ ", 13, 10
DB " | | .\ : . / ;. \,`--.'`| ' :| : : ", 13, 10
DB " . : |: |. ; / ` ;| : : | |. | ;. / ", 13, 10
DB " | | \ :; | ; \ ; |: | \ | :. ; /--` ", 13, 10
DB " | : . /| : | ; | '| : ' '; |; | ; __ ", 13, 10
DB " ; | |`-' . | ' ' ' :' ' ;. ;| : |.' .' ", 13, 10
DB " | | ; ' ; \; / || | | \ |. | '_.' : ", 13, 10
DB " : ' | \ \ ', / ' : | ; .'' ; : \ | ", 13, 10
DB " : : : ; : / | | '`--' ' | '/ .' ", 13, 10
DB " | | : \ \ .' ' : | | : / ", 13, 10
DB " `---'.| `---` ; |.' \ \ .' ", 13, 10
DB " `---` '---' `---` ", 13, 10, '$'
startmsg DB "Click Space To Start!$"
lidor DB "Created By LidorMotai. Inspired By ATARI.$"
wrongb DB "You have clicked the wrong button!$"
c1 DB 0
c2 DB 21
player1top DW 4 ;top pixel
player1count DW 0
comtop DW 110 ;top com pixel
comcount DW 0
ballx DW 150
bally DW 90
p1score DW 0
p2score DW 0
lastaction DW bdleftup
base dw 0
start:
;----------START PAGE-------------
MOV AL, 1 ;PAGE NUMBER
MOV AH, 05H
INT 10H
WindowColor 0,0,80,25,01ch
;PRINT "PONG" TO SCREEN
MOV BH, 1
printstring yay
;SET CURSOR POSITION TO STARTMSG
goto 14,29
;PRINT STARTMSG
printstring startmsg
;SET CURSOR POSITION TO lidor
MOV BH, 1 ;PAGE
curser 20, 20
;PRINT CREATOR(LidorMotai)
MOV DX, OFFSET lidor
MOV AH, 09H
INT 21H
;SET CURSOR POSITION TO lidor
MOV BH, 0 ;PAGE
curser 15,40
;WAIT FOR PLAYER TO CLICK SPACE
MOV AH, 07H
INT 21H
CMP AL, 20H
JNE wrong
JE right
wrong:
MOV BH, 0 ;PAGE
MOV DH, 16 ;ROW
MOV DL, 23 ;COLUMN
MOV AH, 02H
INT 10H
MOV DX, OFFSET wrongb
MOV AH, 09H
INT 21H
jmp end
right:
;-------------------GAME PAGE-------------------
MOV AL, 2 ;PAGE NUMBER
MOV AH, 05H
INT 10H
MOV AX, 13H ;changes the num of pixels to 640X480 with 16 colors
INT 10H
; - - - - - - - - - - Game Code - - - - - - - -
CALL print_ball
CALL print_com
CALL print_batt
balloop bdleftup
;PLAYER1 - CLICK?
checkahit:
p1movecheck:
; PRINT BASE
CALL baseprint
delay 00000001b
;
;CMP p1score, 1
;JE score
MOV AL, 0
MOV AH, 01H
INT 16H
JZ noclick
MOV AH, 00H
INT 16H
CMP AH, 48H
JE P1UP
CMP AH, 50H
JE P1DOWN
P1UP:
CMP player1top, 4
JE checkahit
MOV AL, 13H ;changes the num of pixels to 640X480 with 16 colors
MOV AH, 0
INT 10H
CALL print_com
MOV AX, player1top
SUB AX, 4
MOV player1top, AX
balloop lastaction
JMP hitcheck
CALL print_batt
JMP checkahit
P1DOWN:
CMP player1top, 120
JE checkahit
MOV AL, 13H
MOV AH, 0
INT 10H
CALL print_com
MOV AX, player1top
ADD AX, 4
MOV player1top, AX
CALL print_batt
balloop lastaction
JMP hitcheck
JMP checkahit
noclick:
balloop lastaction
JMP hitcheck
score:
call clearscreen
END:
;MOV AH, 2CH ;TIMER
;INT 21H
;
;CMP DH, 30
;JA NC1
;balloop bdrightup ;BALLOOP CONFIGURATION
;NC1:
;balloop bdrightdown ;BALLOOP CONFIGURATION
排序看起来很有希望：
df = pd.DataFrame({'A' : ['foo', 'foo', 'foo', 'foo', 'bar', 'bar', 'bar', 'bar'],
'B' : ['3', '1', '2', '4','2', '4', '1', '3'],
})
但首先不会给出理想的结果...... df.groupby（ 'A'）。第一个（）
df.sort('B')
A B
1 foo 1
6 bar 1
2 foo 2
4 bar 2
0 foo 3
7 bar 3
3 foo 4
5 bar 4
答案 0 :(得分：10)
pandas groupby函数可以用于你想要的东西，但它真正用于聚合。这是一个简单的“先行”操作。
你真正想要的是pandas drop_duplicates函数，它默认会返回第一行。您通常会考虑groupby键，您应该作为subset = variable
传递df.drop_duplicates(subset='A')
应该做你想做的事。
此外，df.sort('A')不对DataFrame df进行排序，它返回一个已排序的副本。如果要对其进行排序，则必须添加inplace=True参数。
df.sort('A', inplace=True)
答案 1 :(得分：8)
通常，如果您希望您的数据在分组中排序，但它不是要分组的列之一，那么在执行groupby之前最好sort df：
In [5]:
df.sort_values('B').groupby('A').first()
Out[5]:
B
A
bar 1
foo 1
答案 2 :(得分：5)
以下是使用groupby().rank()的替代方法：
df[ df.groupby('A')['B'].rank() == 1 ]
A B
1 foo 1
6 bar 1
对于OP的示例数据帧，这给出了与@ EdChum相同的答案，但如果您在排序期间有任何关系，可以给出不同的答案，例如，使用这样的数据：
df = pd.DataFrame({'A': ['foo', 'foo', 'bar', 'bar'],
'B': ['2', '1', '1', '1'] })
在这种情况下，您可以使用可选的method参数进行选择，具体取决于您希望如何处理排序关系：
df[ df.groupby('A')['B'].rank(method='average') == 1 ] # the default
df[ df.groupby('A')['B'].rank(method='min') == 1 ]
df[ df.groupby('A')['B'].rank(method='first') == 1 ] # doesn't work, not sure why
答案 3 :(得分：3)
EdChum's answer可能并不总是按预期工作。代替first()，请使用nth(0)。
方法first()受this bug的影响，该方法已经解决了很多年。 first()会返回每个组中各列中第一个不丢失的元素，而不是预期的行为，即忽略NaN值。例如，假设您有第三列缺少一些值：
df = pd.DataFrame({'A' : ['foo', 'foo', 'bar', 'bar', 'bar'],
'B' : ['1', '2','2', '4', '1'],
'C' : [np.nan, 'X', 'Y', 'Y', 'Y']})
A B C
0 foo 1 NaN
2 foo 2 X
3 bar 2 Y
4 bar 4 Y
5 bar 1 Y
在此处使用first()（排序之后，就像在答案中正确评估了EdChum一样）将跳过缺少的值（请注意它是如何混合来自不同行的值）：
df.sort_values('B').groupby('A').first()
B C
A
bar 1 Y
foo 1 X
获取完整行（包括缺失值）的正确方法是使用nth(0)，它执行预期的操作：
df.sort_values('B').groupby('A').nth(0)
B C
A
bar 1 Y
foo 1 NaN
为完整性起见，此错误也影响last()，其正确替代词为nth(-1)。
将其发布在答案中，因为评论太长了。不确定这是否在问题范围之内，但我认为它与寻找该答案的许多人有关（就像写此书之前的我一样），而且非常容易错过。
答案 4 :(得分：1)
通常，如果需要在每个组上运行计算，请使用GroupBy（请参阅：split-apply-combine）。
如果您只想保留一列（或列的唯一组合）的每个唯一值的第一行，则可以使用.sort_values()（或.sort_index()）进行排序，然后保留每个第一次出现的值使用.drop_duplicates()。
df.sort_values('A', ascending=True).drop_duplicates('A', keep='first')
这将为您提供非破坏性的结果，其中将保留初始DataFrame结构和索引：
A B
4 bar 2
0 foo 3